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MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

General Description

Features

o Wide 7.5V to 76V Input Voltage Range

The MAX5035 easy-to-use, high-efficiency, high-volt-

age, step-down DC-DC converter operates from an

input voltage up to 76V and consumes only 270µA qui-

escent current at no load. This pulse-width modulated

(PWM) converter operates at a fixed 125kHz switching

frequency at heavy loads, and automatically switches

to pulse-skipping mode to provide low quiescent cur-

rent and high efficiency at light loads. The MAX5035

includes internal frequency compensation simplifying

circuit implementation. The device uses an internal low-

on-resistance, high-voltage, DMOS transistor to obtain

high efficiency and reduce overall system cost. This

device includes undervoltage lockout, cycle-by-cycle

current limit, hiccup mode output short-circuit protec-

tion, and thermal shutdown.

o Fixed (3.3V, 5V, 12V) and Adjustable

(1.25V to 13.2V) Versions

o 1A Output Current

o Efficiency Up to 94%

o Internal 0.4Ω High-Side DMOS FET

o 270µA Quiescent Current at No Load, 10µA

Shutdown Current

o Internal Frequency Compensation

o Fixed 125kHz Switching Frequency

o Thermal Shutdown and Short-Circuit Current

Limit

The MAX5035 delivers up to 1A output current. The out-

put current may be limited by the maximum power dis-

sipation capability of the package. External shutdown is

included, featuring 10µA (typ) shutdown current. The

MAX5035A/B/C versions have fixed output voltages of

3.3V, 5V, and 12V, respectively, while the MAX5035D/E

versions have an adjustable output voltage from 1.25V

to 13.2V.

o 8-Pin SO and PDIP Packages

Ordering Information

OUTPUT

PIN-

PART

TEMP RANGE

VOLTAGE

(V)

PACKAGE

MAX5035AUSA

MAX5035AUPA

MAX5035AASA

0°C to +85°C

8 SO

The MAX5035 is available in space-saving 8-pin SO

and 8-pin plastic DIP packages and operates over the

automotive (-40°C to +125°C) temperature range.

8 PDIP

3.3

5.0

-40°C to +125°C 8 SO

MAX5035AASA/V+ -40°C to +125°C 8 SO

Applications

MAX5035BUSA

MAX5035BUPA

MAX5035BASA

0°C to +85°C

8 SO

8 PDIP

Automotive

-40°C to +125°C 8 SO

Consumer Electronics

Industrial

MAX5035BASA/V+ -40°C to +125°C 8 SO

/V denotes an automotive qualified part.

Distributed Power

+Denotes a lead(Pb)-free/RoHS-compliant package.

Ordering Information continued at end of data sheet.

Typical Operating Circuit

Pin Configuration

V

IN

7.5V TO 76V

V

TOP VIEW

IN

68µF

BST

LX

0.1µF

100µH

MAX5035

V

5V

OUT

BST

VD

1

2

3

4

8

7

6

5

LX

V

R1

R2

D1

50SQ100

IN

MAX5035

ON/OFF

68µF

SGND

FB

GND

ON

FB

VD

ON/OFF

OFF

SGND

GND

0.1µF

SO/PDIP

For pricing, delivery, and ordering information, please contact Maxim Direct

19-2988; Rev 5; 5/11

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

ABSOLUTE MAXIMUM RATINGS

(Voltages referenced to GND, unless otherwise specified.)

VD Short-Circuit Duration ..............................................Indefinite

V

.........................................................................-0.3V to +80V

Continuous Power Dissipation (T = +70°C)

IN

A

SGND ....................................................................-0.3V to +0.3V

LX.................................................................-0.8V to (V + 0.3V)

BST ...............................................................-0.3V to (V + 10V)

8-Pin PDIP (derate 9.1mW/°C above +70°C)...............727mW

8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW

Operating Temperature Range

IN

BST (transient < 100ns)................................-0.3V to (V + 15V)

MAX5035_U_ _ ...................................................0°C to +85°C

MAX5035_A_ _ ..............................................-40°C to +125°C

Storage Temperature Range.............................-65°C to +150°C

Junction Temperature......................................................+150°C

Lead Temperature (soldering, 10s) .................................+300°C

Soldering Temperature (reflow)

IN

BST to LX................................................................-0.3V to +10V

BST to LX (transient < 100ns) ................................-0.3V to +15V

ON/OFF ..................................................................-0.3V to +80V

VD...........................................................................-0.3V to +12V

FB

MAX5035A/MAX5035B/MAX5035C ...................-0.3V to +15V

MAX5035D/E ......................................................-0.3V to +12V

Lead(Pb)-free...............................................................+260°C

Containing lead(Pb).....................................................+240°C

V

Short-Circuit Duration (V ≤ 40V)........................Indefinite

IN

OUT

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS (MAX5035_U_ _)

Typical Application Circuit.)

(V = +12V, V

= +12V, I

= 0, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C. See the

IN

ON/OFF

OUT

A

PARAMETER

SYMBOL

CONDITIONS

MIN

7.5

15

TYP

MAX

76.0

76

UNITS

MAX5035A

MAX5035B

MAX5035C

MAX5035D/E

Input Voltage Range

Undervoltage Lockout

V

IN

7.5

76.0

UVLO

5.2

3.3

V

= 7.5V to 76V,

IN

MAX5035A

MAX5035B

MAX5035C

3.185

4.85

3.415

5.15

I

= 20mA to 1A

OUT

V

= 7.5V to 76V,

IN

Output Voltage

V

5.0

12

V

OUT

I

= 20mA to 1A

= 15V to 76V,

OUT

V

IN

11.64

12.36

I

= 20mA to 1A

OUT

V

= 7.5V to 76V, MAX5035D/E

= 7.5V to 76V, MAX5035E

1.192

1.185

1.221

86

1.250

IN

Feedback Voltage

Efficiency

V

FB

= 12V, I

= 24V, I

= 0.5A, MAX5035A

= 0.5A, MAX5035B

= 0.5A, MAX5035C

LOAD

90

η

94

%

V

= 12V, V

= 5V, I

= 0.5A,

IN

OUT

LOAD

90

MAX5035D/E

V

= 3.5V, V = 7.5V to 76V, MAX5035A

270

340

10

440

460

45

FB

IN

= 5.5V, V = 7.5V to 76V, MAX5035B

FB

IN

Quiescent Supply Current

I

= 13V, V = 15V to 76V, MAX5035C

IN

µA

Q

FB

= 1.3V, MAX5035D

= 1.3V, MAX5035E

FB

Shutdown Current

I

= 0V, V = 7.5V to 76V

µA

A

SHDN

ON/OFF

IN

Peak Switch Current Limit

I

(Note 1)

1.30

1.9

2.50

LIM

2

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

ELECTRICAL CHARACTERISTICS (continued) (MAX5035_U_ _)

Typical Application Circuit.)

(V = +12V, V

= +12V, I

= 0, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C. See the

IN

ON/OFF

OUT

A

PARAMETER

SYMBOL

CONDITIONS

= 0V, V = 0V

MIN

TYP

0.01

0.40

85

MAX

1

UNITS

µA

Switch Leakage Current

Switch On-Resistance

PFM Threshold

I

V

= 76V, V

ON/OFF

OL

IN

LX

R

I

= 1A

0.80

130

+150

Ω

DS(ON)

SWITCH

I

Minimum switch current in any cycle

MAX5035D/E

55

mA

nA

PFM

FB Input Bias Current

ON/OFF CONTROL INPUT

I

-150

+0.01

B

Rising trip point for MAX5035A/B/C/D

Rising trip point for MAX5035E

1.53

1.40

1.69

1.65

100

10

1.85

1.90

ON/OFF Input-Voltage Threshold

V

ON/OFF

ON/OFF Input-Voltage Hysteresis

ON/OFF Input Current

V

mV

nA

HYST

I

V

= 0V to V

IN

150

76

ON/OFF

ON/OFF Operating Voltage

Range

V

ON/OFF

OSCILLATOR

Oscillator Frequency

Maximum Duty Cycle

VOLTAGE REGULATOR

Regulator Output Voltage

Dropout Voltage

f

109

6.9

125

95

135

8.8

kHz

%

OSC

D

MAX5035D/E

MAX

VD

V

= 8.5V to 76V, I = 0

7.8

2.0

V

IN

L

7.5V ≤ V ≤ 8.5V, I = 1mA

IN

L

Load Regulation

∆VD/∆I

0 to 5mA

150

Ω

VD

PACKAGE THERMAL CHARACTERISTICS

SO package (JEDEC 51)

DIP package (JEDEC 51)

170

110

Thermal Resistance

(Junction to Ambient)

θ

JA

°C/W

THERMAL SHUTDOWN

Thermal-Shutdown Junction

Temperature

T

+160

20

°C

SH

Thermal-Shutdown Hysteresis

T

HYST

ELECTRICAL CHARACTERISTICS (MAX5035_A_ _)

the Typical Application Circuit.) (Note 2)

(V = +12V, V

= +12V, I

= 0, T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See

IN

ON/OFF

OUT

A

J

A

PARAMETER SYMBOL

CONDITIONS

MIN

7.5

15

TYP

MAX

76.0

76

UNITS

MAX5035A

MAX5035B

MAX5035C

MAX5035D/E

Input Voltage Range

V

IN

7.5

76.0

Undervoltage Lockout

Output Voltage

UVLO

5.2

3.3

V

= 7.5V to 76V,

IN

MAX5035A

MAX5035B

MAX5035C

3.185

4.825

11.58

3.415

5.175

12.42

I

= 20mA to 1A

OUT

V

= 7.5V to 76V,

IN

V

5.0

12

OUT

I

= 20mA to 1A

= 15V to 76V,

OUT

V

IN

I

= 20mA to 1A

OUT

Maxim Integrated

3

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

ELECTRICAL CHARACTERISTICS (MAX5035_A_ _) (continued)

the Typical Application Circuit.) (Note 2)

(V = +12V, V

= +12V, I

= 0, T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See

IN

ON/OFF

OUT

A

J

A

PARAMETER SYMBOL

CONDITIONS

= 7.5V to 76V, MAX5035D

= 7.5V to 76V, MAX5035E

MIN

TYP

1.221

86

MAX

1.250

UNITS

V

1.192

1.185

IN

Feedback Voltage

V

FB

= 12V, I

= 24V, I

= 0.5A, MAX5035A

= 0.5A, MAX5035B

= 0.5A, MAX5035C

LOAD

90

Efficiency

η

%

94

= 12V, V

= 5V, I

= 0.5A,

OUT

LOAD

90

MAX5035D/E

V

= 3.5V, V = 7.5V to 76V, MAX5035A

270

340

10

440

460

45

FB

IN

= 5.5V, V = 7.5V to 76V, MAX5035B

FB

IN

Quiescent Supply Current

I

= 13V, V = 15V to 76V, MAX5035C

IN

µA

Q

FB

= 1.3V, MAX5035D

= 1.3V, MAX5035E

FB

Shutdown Current

I

= 0V, V = 7.5V to 76V

µA

A

SHDN

ON/OFF

IN

Peak Switch Current Limit

I

(Note 1)

1.30

1.9

1

2.50

LIM

V

= 76V, V

= 0V, V = 0V

LX

IN

ON/OFF

Switch Leakage Current

I

µA

OL

V

= 76V, V

= 0V, V = 0V,

IN

LX

5

MAX5035E

Switch On-Resistance

PFM Threshold

R

I

= 1A

0.40

85

0.80

130

Ω

DS(ON)

SWITCH

I

Minimum switch current in any cycle

MAX5035D/E

55

mA

nA

PFM

FB Input Bias Current

ON/OFF CONTROL INPUT

I

-150

+0.01

+150

B

Rising trip point for MAX5035A/B/C/D

Rising trip point for MAX5035E

1.50

1.40

1.69

1.65

100

10

1.85

1.90

ON/OFF Input-Voltage Threshold

V

ON/OFF

ON/OFF Input-Voltage Hysteresis

ON/OFF Input Current

V

mV

nA

HYST

I

V

= 0V to V

IN

150

76

ON/OFF

ON/OFF Operating Voltage

Range

V

ON/OFF

OSCILLATOR

Oscillator Frequency

Maximum Duty Cycle

VOLTAGE REGULATOR

Regulator Output Voltage

Dropout Voltage

f

105

6.5

125

95

137

9.0

kHz

%

OSC

D

MAX5035D/E

MAX

VD

V

= 8.5V to 76V, I = 0

7.8

2.0

150

V

IN

L

7.5V ≤ V ≤ 8.5V, I = 1mA

IN

L

Load Regulation

∆VD/∆I

0 to 5mA

Ω

VD

4

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

ELECTRICAL CHARACTERISTICS (MAX5035_A_ _) (continued)

the Typical Application Circuit.) (Note 2)

(V = +12V, V

= +12V, I

= 0, T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See

IN

ON/OFF

OUT

A

J

A

PARAMETER SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

PACKAGE THERMAL CHARACTERISTICS

SO package (JEDEC 51)

DIP package (JEDEC 51)

170

110

Thermal Resistance

(Junction to Ambient)

θ

JA

°C/W

THERMAL SHUTDOWN

Thermal-Shutdown Junction

Temperature

T

+160

20

°C

SH

Thermal-Shutdown Hysteresis

T

HYST

Note 1: Switch current at which current limit is activated.

Note 2: All limits at -40°C are guaranteed by design, not production tested.

Typical Operating Characteristics

(V = 12V, V

Application Circuit, if applicable.)

= 12V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See the Typical

A A

IN

ON/OFF

V

vs. TEMPERATURE

V

vs. TEMPERATURE

OUT

(MAX5035AASA, V

= 3.3V)

(MAX5035DASA, V

= 5V)

OUT

3.40

3.36

3.32

3.28

5.20

5.15

5.10

5.05

5.00

4.95

4.90

4.85

4.80

3.40

3.36

3.32

3.28

I

= 0.1A

I

= 0.1A

OUT

I

= 1A

OUT

I

= 1A

OUT

I

= 0.1A

OUT

I

= 1A

OUT

3.24

3.20

3.24

3.20

25

75

125

100

150

-50 -25

0

50

5

20

35

50

65

80

-50 -25

0

25 50 75 100 125 150

TEMPERATURE (°C)

INPUT VOLTAGE (V)

LOAD REGULATION

(MAX5035AASA, V = 3.3V)

LINE REGULATION

(MAX5035DASA, V = 5V)

LOAD REGULATION

OUT

(MAX5035DASA, V

= 5V)

OUT

3.40

5.20

5.15

5.10

5.05

5.00

4.95

4.90

4.85

4.80

5.10

5.05

5.00

4.95

4.90

V

= 76V

IN

3.36

3.32

3.28

3.24

3.20

V

= 7.5V, 24V

IN

V

= 24V

IN

I

= 0.1A

OUT

V

= 7.5V

IN

I

= 1A

OUT

V

= 76V

IN

0

200

400

I

600

(mA)

800

1000

5

20

35

50

65

80

0

200

400

I

600

(mA)

800

1000

INPUT VOLTAGE (V)

LOAD

Maxim Integrated

5

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Typical Operating Characteristics (continued)

(V = 12V, V

Application Circuit, if applicable.)

= 12V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See the Typical

IN

ON/OFF

A

EFFICIENCY vs. LOAD CURRENT

(MAX5035DASA, V

= 12V)

(MAX5035AASA, V

= 3.3V)

(MAX5035DASA, V

= 5V)

OUT

100

90

80

70

60

50

40

30

20

10

0

100

90

80

70

60

50

40

30

20

10

0

100

90

80

70

60

50

40

30

20

10

0

V

= 15V

IN

V

= 7.5V

V = 7.5V

IN

V

= 24V

IN

V

= 12V

V = 12V

IN

V

= 48V

IN

V

= 24V

V = 24V

IN

V

= 76V

IN

V

= 48V

V = 48V

IN

V

= 76V

V

= 76V

IN

0

200

400

600

800

1000

0

200

400

600

800

1000

0

200

400

600

800

1000

LOAD CURRENT (mA)

OUTPUT CURRENT LIMIT

vs. TEMPERATURE

OUTPUT CURRENT LIMIT

vs. INPUT VOLTAGE

QUIESCENT SUPPLY CURRENT

vs. TEMPERATURE

2.0

1.5

1.0

0.5

0

2.0

350

320

290

260

230

200

1.7

1.4

1.1

0.8

0.5

MAX5035DASA

= 5V

V

= 5V

OUT

V

OUT

5% DROP IN V

OUT

5% DROP IN VOUT

-50 -25

0

25 50 75 100 125 150

5

20

35

50 65

80

25

75

125

100

150

-50 -25

0

50

TEMPERATURE (°C)

INPUT VOLTAGE (V)

TEMPERATURE (°C)

SHUTDOWN CURRENT

vs. TEMPERATURE

QUIESCENT SUPPLY CURRENT

vs. INPUT VOLTAGE

SHUTDOWN CURRENT vs. INPUT VOLTAGE

25

350

320

290

260

230

200

20

16

12

8

20

15

10

5

4

0

25

75

125

100

150

-50 -25

0

50

6

16

26

36

46

56

66

76

6

16

26

36

46

56

66

76

TEMPERATURE (°C)

INPUT VOLTAGE (V)

6

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Typical Operating Characteristics (continued)

(V = 12V, V

Application Circuit, if applicable.)

= 12V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See the Typical

IN

ON/OFF

A

MAX5035DASA

LOAD-TRANSIENT RESPONSE

OUTPUT VOLTAGE

vs. INPUT VOLTAGE

MAX5035DASA

LOAD-TRANSIENT RESPONSE

MAX5035 toc17

MAX5035 toc18

15

MAX5035DASA

V

= 5V

OUT

V

= 5V

OUT

V

= 12V

= V

OUT

/

12

9

ON OFF

IN

A

B

A

B

6

I

= 1A

OUT

3

I

= 0.3A

OUT

I

= 0

9

OUT

(V)

0

3

6

12

15

400µs/div

V

A: V , 200mV/div, AC-COUPLED

OUT

B: I , 500mA/div, 0.1A TO 1A

OUT

IN

A: V , 200mV/div, AC-COUPLED

OUT

B: I , 500mA/div, 0.5A TO 1A

OUT

MAX5035DASA

LOAD-TRANSIENT RESPONSE

MAX5035DASA LX WAVEFORMS

MAX5035 toc20

MAX5035 toc21

MAX5035 toc19

V

= 5V

OUT

A

0

A

0

B

0

B

0

B

4µs/div

400µs/div

A: SWITCH VOLTAGE (LX PIN), 20V/div (V = 48V)

IN

A: SWITCH VOLTAGE (LX PIN), 20V/div (V = 48V)

IN

A: V , 200mV/div, AC-COUPLED

OUT

B: I , 500mA/div, 0.1A TO 0.5A

OUT

B: INDUCTOR CURRENT, 500mA/div (I

= 1A)

B: INDUCTOR CURRENT, 200mA/div (I

= 100mA)

OUT

Maxim Integrated

7

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Typical Operating Characteristics (continued)

(V = 12V, V

Application Circuit, if applicable.)

= 12V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C. See the Typical

IN

ON/OFF

A

MAX5035DASA STARTUP WAVEFORM

MAX5035DASA LX WAVEFORMS

(I = 0)

O

MAX5035 toc23

MAX5035 toc22

A

B

A

0

B

0

1ms/div

4µs/div

A: V

, 2V/div

A: SWITCH VOLTAGE (LX PIN), 20V/div (V = 48V)

IN

ON/OFF

B: V , 2V/div

OUT

B: INDUCTOR CURRENT, 200mA/div (I

= 0)

OUT

MAX5035DASA STARTUP WAVEFORM

PEAK SWITCH CURRENT LIMIT

vs. INPUT VOLTAGE

(I = 1A)

O

MAX5035 toc24

3.0

2.5

2.0

1.5

1.0

0.5

A

B

0

MAX5035DASA

V

OUT

= 5V

5% DROP IN V

OUT

1ms/div

6

16

26

36

46

56

66

76

INPUT VOLTAGE (V)

A: V

, 2V/div

ON/OFF

B: V , 2V/div

OUT

8

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Pin Description

1

NAME

BST

FUNCTION

Boost Capacitor Connection. Connect a 0.1µF ceramic capacitor from BST to LX.

Internal Regulator Output. Bypass VD to GND with a 0.1µF ceramic capacitor.

Internal Connection. SGND must be connected to GND.

2

VD

3

SGND

Output Sense Feedback Connection. For fixed output voltage (MAX5035A, MAX5035B, MAX5035C),

connect FB to V . For adjustable output voltage (MAX5035D, MAX5035E), use an external resistive

OUT

4

FB

voltage-divider to set V

. V regulating set point is 1.22V.

OUT FB

Shutdown Control Input. Pull ON/OFF low to put the device in shutdown mode. Drive ON/OFF high for

normal operation.

5

ON/OFF

6

7

8

GND

Ground

V

Input Voltage. Bypass V to GND with a low ESR capacitor as close to the device as possible.

IN

LX

Source Connection of Internal High-Side Switch

Block Diagram

V

ON/OFF

IN

ENABLE

REGULATOR

(FOR ANALOG)

I

CPFM

CILIM

REF-PFM

1.69V

HIGH-SIDE

CURRENT

SENSE

REGULATOR

(FOR DRIVER)

VD

OSC

V

RAMP

REF

I

REF-LIM

BST

MAX5035

CLK

CONTROL

LOGIC

FB

RAMP

R

h

TYPE 3

COMPENSATION

x1

THERMAL

SHUTDOWN

CPWM

V

REF

R

l

EAMP

GND

LX

SGND

Maxim Integrated

9

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

On startup, an internal low-side switch connects LX to

Detailed Description

ground and charges the BST capacitor to VD. Once the

BST capacitor is charged, the internal low-side switch

is turned off and the BST capacitor voltage provides

the necessary enhancement voltage to turn on the

high-side switch.

The MAX5035 step-down DC-DC converter operates

from a 7.5V to 76V input voltage range. A unique volt-

age-mode control scheme with voltage feed-forward

and an internal switching DMOS FET provides high effi-

ciency over a wide input voltage range. This pulse-

width modulated converter operates at a fixed 125kHz

switching frequency. The device also features automat-

ic pulse-skipping mode to provide low quiescent cur-

rent and high efficiency at light loads. Under no load,

the MAX5035 consumes only 270µA, and in shutdown

mode, consumes only 10µA. The MAX5035 also fea-

tures undervoltage lockout, hiccup mode output short-

circuit protection, and thermal shutdown.

Thermal-Overload Protection

The MAX5035 features integrated thermal overload pro-

tection. Thermal overload protection limits total power

dissipation in the device, and protects the device in the

event of a fault condition. When the die temperature

exceeds +160°C, an internal thermal sensor signals the

shutdown logic, turning off the internal power MOSFET

and allowing the IC to cool. The thermal sensor turns the

internal power MOSFET back on after the IC’s die tem-

perature cools down to +140°C, resulting in a pulsed

output under continuous thermal overload conditions.

Shutdown Mode

Drive ON/OFF to ground to shut down the MAX5035.

Shutdown forces the internal power MOSFET off, turns

off all internal circuitry, and reduces the V supply cur-

IN

Applications Information

rent to 10µA (typ). The ON/OFF rising threshold is

1.69V (typ). Before any operation begins, the voltage at

ON/OFF must exceed 1.69V (typ). The ON/OFF input

has 100mV hysteresis.

Setting the Output Voltage

The MAX5035A/B/C have preset output voltages of 3.3V,

5.0V, and 12V, respectively. Connect FB to the preset

output voltage (see the Typical Operating Circuit).

Undervoltage Lockout (UVLO)

Use the ON/OFF function to program the UVLO thresh-

old at the input. Connect a resistive voltage-divider

from V to GND with the center node to ON/OFF as

shown in Figure 1. Calculate the threshold value by

using the following formula:

The MAX5035D/E versions offer an adjustable output

voltage. Set the output voltage with a resistive voltage-

divider connected from the circuit’s output to ground

(Figure 1). Connect the center node of the divider to

FB. Choose R4 less than 15kΩ, then calculate R3 as

follows:

IN

R1

R2

⎛

⎞

(V

−1.22)

1.22

V

= 1 +

×1.85V

OUT

UVLO(TH)

⎜

⎝

⎟

⎠

R3 =

× R4

The minimum recommended V

is 6.5V, 7.5V, and

UVLO(TH)

13V for the output voltages of 3.3V, 5V, and 12V, respec-

tively. The recommended value for R2 is less than 1MΩ.

V

IN

7.5V TO 76V

If the external UVLO threshold-setting divider is not

used, an internal undervoltage-lockout feature monitors

68µF

V

5V

OUT

the supply voltage at V and allows operation to start

IN

100µH

V

IN

when V rises above 5.2V (typ). This feature can be

IN

LX

R1

R2

used only when V rise time is faster than 2ms. For

IN

0.1µF

C

68µF

OUT

D1

50SQ100

ON/OFF

slower V rise time, use the resistive-divider at

IN

BST

ON/OFF.

R3

41.2kΩ

MAX5035D

Boost High-Side Gate Drive (BST)

Connect a flying bootstrap capacitor between LX and

BST to provide the gate-drive voltage to the high-side

N-channel DMOS switch. The capacitor is alternately

charged from the internally regulated output voltage VD

and placed across the high-side DMOS driver. Use a

0.1µF, 16V ceramic capacitor located as close to the

device as possible.

FB

VD

R4

13.3kΩ

SGND GND

0.1µF

Figure 1. Adjustable Output Voltage

10

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

The MAX5035 features internal compensation for opti-

mum closed-loop bandwidth and phase margin. With

the preset compensation, it is strongly advised to sense

the output immediately after the primary LC.

drop (V ) less than 0.45V at +25°C and maximum load

FB

current to avoid forward biasing of the internal body

diode (LX to ground). Internal body diode conduction

may cause excessive junction temperature rise and

thermal shutdown. Use Table 1 to choose the proper

rectifier at different input voltages and output current.

Inductor Selection

The choice of an inductor is guided by the voltage dif-

ference between V and V

, the required output

OUT

Input Bypass Capacitor

The discontinuous input-current waveform of the buck

converter causes large ripple currents in the input

capacitor. The switching frequency, peak inductor cur-

rent, and the allowable peak-to-peak voltage ripple that

reflects back to the source dictate the capacitance

requirement. The MAX5035 high switching frequency

allows the use of smaller-value input capacitors.

IN

current, and the operating frequency of the circuit. Use

an inductor with a minimum value given by:

(V − V

) × D

× f

SW

IN

OUT

L =

0.3 × I

OUTMAX

where:

The input ripple is comprised of ∆V (caused by the

Q

V

capacitor discharge) and ∆V

(caused by the ESR of

OUT

ESR

D =

the capacitor). Use low-ESR aluminum electrolytic

capacitors with high ripple-current capability at the input.

Assuming that the contribution from the ESR and capaci-

tor discharge is equal to 90% and 10%, respectively, cal-

culate the input capacitance and the ESR required for a

specified ripple using the following equations:

IN

I

is the maximum output current required, and

OUTMAX

f

is the operating frequency of 125kHz. Use an induc-

SW

tor with a maximum saturation current rating equal to at

least the peak switch current limit (I ). Use inductors

LIM

with low DC resistance for higher efficiency.

∆V

ESR

=

IN

Selecting a Rectifier

The MAX5035 requires an external Schottky rectifier as

a freewheeling diode. Connect this rectifier close to the

device using short leads and short PC board traces.

Choose a rectifier with a continuous current rating

greater than the highest expected output current. Use a

rectifier with a voltage rating greater than the maximum

∆I

⎛

⎞

L

I

+

OUT

⎜

⎝

⎟

⎠

2

I

× D (1− D)

OUT

C

=

IN

∆V × f

Q

SW

where :

(V − V

) × V

OUT

expected input voltage, V . Use a low forward-voltage

IN

OUT

× f

∆I

=

,

L

Schottky rectifier for proper operation and high efficien-

cy. Avoid higher than necessary reverse-voltage

Schottky rectifiers that have higher forward-voltage

drops. Use a Schottky rectifier with forward-voltage

V

× L

IN

SW

V

OUT

D =

IN

Table 1. Diode Selection

I

is the maximum output current of the converter

V

IN

(V) DIODE PART NUMBER

15MQ040N

MANUFACTURER

IR

OUT

and f

is the oscillator switching frequency (125kHz).

SW

For example, at V = 48V, V

= 3.3V, the ESR and

OUT

IN

B240A

Diodes, Inc.

input capacitance are calculated for the input peak-to-

peak ripple of 100mV or less yielding an ESR and

capacitance value of 80mΩ and 51µF, respectively.

Low-ESR, ceramic, multilayer chip capacitors are recom-

mended for size-optimized application. For ceramic

capacitors, assume the contribution from ESR and capaci-

tor discharge is equal to 10% and 90%, respectively.

7.5 to 36

B240

MBRS240, MBRS1540

30BQ060

Central Semiconductor

ON Semiconductor

IR

B360A

Diodes, Inc.

7.5 to 56

7.5 to 76

CMSH3-60

Central Semiconductor

ON Semiconductor

IR

MBRD360, MBR3060

50SQ100, 50SQ80

MBRM5100

The input capacitor must handle the RMS ripple current

without significant rise in temperature. The maximum

capacitor RMS current occurs at about 50% duty cycle.

Diodes, Inc.

Maxim Integrated

11

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Ensure that the ripple specification of the input capaci-

tor exceeds the worst-case capacitor RMS ripple cur-

rent. Use the following equations to calculate the input

capacitor RMS current:

capacitance and the ESR required for a specified rip-

ple using the following equations:

∆V

OESR

ESR

=

OUT

∆I

L

2

I

= I

− I

CRMS

PRMS AVGIN

where :

∆I

L

C

≈

OUT

2.2 × ∆V

× f

SW

OQ

D

3

2

I

=

I

+ I

+ I × I

×

(

)

(

)

PRMS

PK

DC

PK DC

The MAX5035 has an internal soft-start time (t ) of

SS

V

× I

OUT

V

400µs. It is important to keep the output rise time at

I

=

AVGIN

× η

startup below t to avoid output overshoot. The output

SS

IN

rise time is directly proportional to the output capacitor.

Use 68µF or lower capacitance at the output to control

the overshoot below 5%.

∆I

2

∆I

L

= I

+

,I

= I

−

OUT

PK

OUT

DC

2

V

OUT

andD =

In a dynamic load application, the allowable deviation

of the output voltage during the fast-transient load dic-

tates the output capacitance value and the ESR. The

output capacitors supply the step load current until the

controller responds with a greater duty cycle. The

V

IN

I

is the input switch RMS current, I

is the

AVGIN

PRMS

input average current, and η is the converter efficiency.

The ESR of aluminum electrolytic capacitors increases

significantly at cold temperatures. Use a 1µF or greater

value ceramic capacitor in parallel with the aluminum

electrolytic input capacitor, especially for input voltages

below 8V.

response time (t

) depends on the closed-

RESPONSE

loop bandwidth of the converter. The resistive drop

across the capacitor ESR and capacitor discharge

cause a voltage droop during a step load. Use a com-

bination of low-ESR tantalum and ceramic capacitors

for better transient load and ripple/noise performance.

Keep the maximum output-voltage deviation above the

tolerable limits of the electronics being powered.

Assuming a 50% contribution each from the output

capacitance discharge and the ESR drop, use the fol-

lowing equations to calculate the required ESR and

capacitance value:

Output Filter Capacitor

The worst-case peak-to-peak and RMS capacitor ripple

current, allowable peak-to-peak output ripple voltage,

and the maximum deviation of the output voltage dur-

ing load steps determine the capacitance and the ESR

requirements for the output capacitors.

The output capacitance and its ESR form a zero, which

improves the closed-loop stability of the buck regulator.

Choose the output capacitor so the ESR zero frequency

∆V

OESR

STEP

ESR

=

OUT

I

(f ) occurs between 20kHz to 40kHz. Use the following

Z

equation to verify the value of f . Capacitors with 100mΩ

Z

to 250mΩ ESR are recommended to ensure the closed-

I

× t

STEP

RESPONSE

C

=

OUT

loop stability, while keeping the output ripple low.

∆V

OQ

1

f

=

where I

is the load step and t

is the

RESPONSE

Z

STEP

2 × π × C

× ESR

OUT

response time of the controller. Controller response

time is approximately one-third of the reciprocal of the

closed-loop unity-gain bandwidth, 20kHz typically.

The output ripple is comprised of ∆V

(caused by the

OQ

capacitor discharge) and ∆V

(caused by the ESR

OESR

of the capacitor). Use low-ESR tantalum or aluminum

electrolytic capacitors at the output. Assuming that the

contributions from the ESR and capacitor discharge

equal 80% and 20% respectively, calculate the output

PCB Layout Considerations

Proper PCB layout is essential. Minimize ground noise

by connecting the anode of the Schottky rectifier, the

input bypass capacitor ground lead, and the output fil-

ter capacitor ground lead to a single point (“star”

12

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

ground configuration). A ground plane is required.

device. Also, place BST and VD bypass capacitors

very close to the device. Use the PC board copper

Minimize lead lengths to reduce stray capacitance,

trace resistance, and radiated noise. In particular,

place the Schottky rectifier diode right next to the

plane connecting to V and LX for heatsinking.

IN

Application Circuits

V

IN

C

IN

V

IN

BST

LX

0.1µF

L1

V

OUT

D1

R1

R2

C

OUT

MAX5035

ON/OFF

FB

VD

SGND GND

0.1µF

Figure 2. Fixed Output Voltages

Table 2. Typical External Components Selection (Circuit of Figure 2)

V

IN

(V)

V

(V)

I (A)

OUT

EXTERNAL COMPONENTS

OUT

C

= 68µF, Panasonic, EEVFK2A680Q

IN

= 68µF, Vishay Sprague, 594D686X_010C2T

= 0.1µF, 0805

OUT

BST

7.5 to 76

3.3

0.5

R1 = 1MΩ 1%, 0805

R2 = 384kΩ 1%, 0805

D1 = 50SQ100, IR

L1 = 100µH, Coilcraft Inc., DO5022P-104

3.3

5

1

C

= 68µF, Panasonic, EEVFK2A680Q

IN

= 68µF, Vishay Sprague, 594D68X_010C2T

= 0.1µF, 0805

OUT

0.5

1

BST

R1 = 1MΩ 1%, 0805

R2 = 384kΩ 1%, 0805

D1 = 50SQ100, IR

5

L1 = 100µH, Coilcraft Inc., DO5022P-104

C

= 68µF, Panasonic, EEVFK2A680Q

IN

= 15µF, Vishay Sprague, 594D156X0025C2T

= 0.1µF, 0805

OUT

BST

R1 = 1MΩ 1%, 0805

15 to 76

12

1

R2 = 139kΩ 1%, 0805

D1 = 50SQ100, IR

L1 = 220µH, Coilcraft Inc., DO5022P-224

Maxim Integrated

13

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Table 2. Typical External Components Selection (Circuit of Figure 2) (continued)

V

IN

(V)

V

(V)

I

(A)

EXTERNAL COMPONENTS

OUT

C

= 220µF, Panasonic, EEVFK1E221P

IN

= 68µF, Vishay Sprague, 594D686X_010C2T

= 0.1µF, 0805

OUT

BST

3.3

1

R1 = 1MΩ 1%, 0805

R2 = 274kΩ 1%, 0805

D1 = B220, Diodes Inc.

L1 = 100µH, Coilcraft Inc., DO5022P-104

9 to 14

C

= 220µF, Panasonic, EEVFK1E221P

IN

= 68µF, Vishay Sprague, 594D686X_010C2T

= 0.1µF, 0805

OUT

BST

5

3.3

5

1

R1 = 1MΩ 1%, 0805

R2 = 274kΩ 1%, 0805

D1 = B220, Diodes Inc.

L1 = 100µH, Coilcraft Inc., DO5022P-104

C

= 220µF, Panasonic, EEVFK1H221P

IN

= 68µF, Vishay Sprague, 594D686X_010C2T

= 0.1µF, 0805

OUT

BST

R1 = 1MΩ 1%, 0805

R2 = 130kΩ 1%, 0805

D1 = MBRS2040, ON Semiconductor

L1 = 100µH, Coilcraft Inc., DO5022P-104

C

= 220µF, Panasonic, EEVFK1H221P

IN

= 68µF, Vishay Sprague, 594D686X_010C2T

= 0.1µF, 0805

OUT

BST

18 to 36

R1 = 1MΩ 1%, 0805

R2 = 130kΩ 1%, 0805

D1 = MBRS2040, ON Semiconductor

L1 = 100µH, Coilcraft Inc., DO5022P-104

C

= 220µF, Panasonic, EEVFK1H221P

IN

= 15µF, Vishay Sprague, 594D156X_0025C2T

= 0.1µF, 0805

OUT

BST

12

R1 = 1MΩ 1%, 0805

R2 = 130kΩ 1%, 0805

D1 = MBRS2040, ON Semiconductor

L1 = 220µH, Coilcraft Inc., DO5022P-224

14

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Table 3. Component Suppliers

SUPPLIER

AVX Corporation

PHONE

FAX

WEBSITE

www.avxcorp.com

www.coilcraft.com

www.diodes.com

843-946-0238

847-639-6400

805-446-4800

800-344-2112

619-661-6835

847-803-6100

402-563-6866

843-626-3123

847-639-1469

805-446-4850

714-737-7323

619-661-1055

847-390-4405

402-563-6296

Coilcraft, Inc.

Diodes Incorporated

Panasonic Corp.

SANYO Electric Co., Ltd.

TDK Corp.

www.panasonic.com

www.sanyo.com

www.component.tdk.com

www.vishay.com

Vishay

MAX5035

FB

BST

PTC*

ON/OFF

L1

100µH

V

OUT

0.1µF

5V AT 1A

V

12V

IN

V

LX

IN

C

68µF

IN

VD

Rt

Ct

D1

B240

SGND GND

C

OUT

68µF

0.1µF

*LOCATE PTC AS CLOSE TO HEAT-DISSIPATING COMPONENTS AS POSSIBLE.

Figure 3. Load Temperature Monitoring with ON/OFF (Requires Accurate V

)

IN

Maxim Integrated

15

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

FB

MAX5035B

R1

BST

ON/OFF

L1

220µH

V

5V

OUT

0.1µF

V

IN

V

LX

IN

7.5V TO 36V

C

68µF

OUT

C

68µF

IN

VD

Rt

Ct

D1

B240

SGND GND

0.1µF

FB

MAX5035A

R1'

BST

ON/OFF

L1'

100µH

V'

3.3V

OUT

0.1µF

V

IN

LX

C'

68µF

OUT

C'

68µF

IN

VD

Rt'

Ct'

D1'

B240

SGND GND

0.1µF

Figure 4. Dual-Sequenced DC-DC Converters (Startup Delay Determined by R1/R1’, Ct/Ct’ and Rt/Rt’)

Ordering Information (continued)

Chip Information

PROCESS: BiCMOS

OUTPUT

VOLTAGE

(V)

PIN-

PACKAGE

PART

TEMP RANGE

MAX5035CUSA

MAX5035CUPA

MAX5035CASA

0°C to +85°C

8 SO

Package Information

8 PDIP

For the latest package outline information and land patterns

(footprints), go to www.maxim-ic.com/packages. Note that a

“+”, “#”, or “-” in the package code indicates RoHS status only.

Package drawings may show a different suffix character, but

the drawing pertains to the package regardless of RoHS status.

12

-40°C to +125°C 8 SO

MAX5035CASA/V+ -40°C to +125°C 8 SO

MAX5035DUSA

MAX5035DUPA

MAX5035DASA

0°C to +85°C

8 SO

8 PDIP

LAND

PACKAGE

TYPE

PACKAGE

CODE

ADJ

OUTLINE NO.

-40°C to +125°C 8 SO

PATTERN NO.

90-0096

—

MAX5035DASA/V+ -40°C to +125°C 8 SO

8 SO

S8+2

21-0041

21-0043

MAX5035EUSA

MAX5035EASA

0°C to +85°C

8 SO

8 PDIP

P8+1

-40°C to +125°C 8 SO

MAX5035EASA/V+ -40°C to +125°C 8 SO

/V denotes an automotive qualified part.

+Denotes a lead(Pb)-free/RoHS-compliant package.

16

Maxim Integrated

MAX5035

1A, 76V, High-Efficiency MAXPower

Step-Down DC-DC Converter

Revision History

REVISION

NUMBER

REVISION

DATE

PAGES

DESCRIPTION

CHANGED

0

1

9/03

6/04

Initial release

—

Removed future-product asterisks and made specification changes

1, 2, 3

2

1/07

Modified Absolute Maximum Ratings section, updated Ordering Information, style edits

2, 3

3

4

5

5/09

4/10

5/11

Modified Absolute Maximum Ratings section

Updated Electrical Characteristics table specifications

Added new variant (MAX5035E)

1, 2, 16, 18

2, 3, 4, 16, 17

1–4, 9, 10, 16

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.

Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical

Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

17

The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.

Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000

©

2011 Maxim Integrated

型号:	MAX5035DASA
是否无铅：	含铅
是否Rohs认证：	不符合
生命周期：	Obsolete
零件包装代码：	SOIC
包装说明：	SOP, SOP8,.25
针数：	8
Reach Compliance Code：	not_compliant
ECCN代码：	EAR99
HTS代码：	8542.39.00.01
Factory Lead Time：	1 week
风险等级：	5.07
其他特性：	ALSO HAS A CONTROL TECHNIQUE OF PFM, OPERATES IN ADJUSTABLE MODE FROM 1.25 TO 13.2V
模拟集成电路 - 其他类型：	SWITCHING REGULATOR
控制模式：	VOLTAGE-MODE
控制技术：	PULSE WIDTH MODULATION
最大输入电压：	76 V
最小输入电压：	7.5 V
标称输入电压：	12 V
JESD-30 代码：	R-PDSO-G8
JESD-609代码：	e0
长度：	4.9 mm
湿度敏感等级：	1
功能数量：	1
端子数量：	8
最高工作温度：	125 °C
最低工作温度：	-40 °C
最大输出电流：	2.5 A
封装主体材料：	PLASTIC/EPOXY
封装代码：	SOP
封装等效代码：	SOP8,.25
封装形状：	RECTANGULAR
封装形式：	SMALL OUTLINE
峰值回流温度（摄氏度）：	245
认证状态：	Not Qualified
座面最大高度：	1.75 mm
子类别：	Switching Regulator or Controllers
表面贴装：	YES
切换器配置：	BUCK
最大切换频率：	137 kHz
技术：	BICMOS
温度等级：	AUTOMOTIVE
端子面层：	Tin/Lead (Sn85Pb15)
端子形式：	GULL WING
端子节距：	1.27 mm
端子位置：	DUAL
处于峰值回流温度下的最长时间：	NOT SPECIFIED
宽度：	3.9 mm
Base Number Matches：	1

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