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SC553

150mA Ultra Low Dropout

Regulator with Adjustable Output

POWER MANAGEMENT

Description

Features

The SC553 is a low dropout linear regulator that

operates from a +2.25V to +6.5V input range and

delivers up to 150mA. A PMOS pass transistor allows

the low 75µA supply current to remain independent of

load, making these devices ideal for battery operated

portable equipment such as cellular phones, cordless

phones and personal digital assistants.

! “5205” compatible pinout

! 2% output accuracy guaranteed over line, load and

temperature

! Guaranteed 150 mA output current

! Very small external components - designed to work

with ceramic capacitors

! Output adjustable from 1.25V to 6V

! Very low supply current

! Thermal overload protection

! Reverse battery protection

! Low power shutdown

! Full industrial temperature range

! Surface mount packaging (5 pin SOT-23)

The SC553 has an adjust pin (ADJ) enabling the user to

set the output voltage anywhere from 1.25V to 6V. For a

low noise version, see SC1453 and for an error flag see

SC1457. Other features include low powered shutdown,

short circuit protection, thermal shutdown protection and

reverse battery protection. The SC553 comes in the tiny

5 lead SOT-23 package.

Applications

! Battery Powered Systems

! Cellular Telephones

! Cordless Telephones

! Personal Digital Assistants

! Portable Instrumentation

! Modems

! PCMCIA cards

Typical Application Circuit

U1

SC553

OUT

5

4

1

3

VOUT

VIN

IN

C1

R1

R2

C2

EN

ADJ

1uF

GND

2

1uF

R1

R2







V_OUT= 1.250 • 1+







Revision: April 20, 2004

1

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SC553

POWER MANAGEMENT

Absolute Maximum Ratings

Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified

in the Electrical Characteristics section is not implied.

Parameter

Symbol

Maximum

Units

Input Supply Voltage

V_IN

V_EN

V_OUT

V_ADJ

θ_JA

-0.6 to +7

-0.6 to V_IN

-0.6 to +7

256

V

Enable Voltage

Output Pin Voltage

V

Adjust Pin Voltage

V

Thermal Resistance Junction to Ambient

Thermal Resistance Junction to Case

Operating Ambient Temperature Range

Operating Junction Temperature Range

Storage Temperature Range

Lead Temperature (Soldering) 10 Sec.

°C/W

°C

81

θ_JC

T_A

-40 to +85

-40 to +125

-65 to 150

300

T_J

°C

T_STG

T_LEAD

°C

Electrical Characteristics

Unless specified: V_IN= 2.25V, V_EN= V_IN, I_OUT= 100µA, C_IN= C_OUT= 1µF, T_A= 25°C. Values in bold apply over full operating ambient temperature range.

Parameter

Symbol

Conditions

Min

Typ

Max

Units

IN

Supply Voltage Range

Supply Current

V_IN

I_Q

2.25

6.50

130

160

1.0

V

I_OUT= 0mA to150mA, 2.25V ≤ V_IN≤ 6.5V

75

µA

Off-State Supply Current

I_Q(OFF)

V_IN= 6.5V, V_EN= 0V

0.1

µA

1.5

ADJ

Adjust Pin Voltage ⁽¹⁾

V_ADJ

I_OUT= 1mA

0mA ≤ I_OUT≤ 150mA, 2.25V ≤ V_IN≤ 5.5V

V_ADJ= 1.3V

-1.5%

1.250

0.015

+1.5%

+2.0%

2.500

5.000

V

-2.0%

Adjust Pin Input Current ⁽²⁾

I_ADJ

nA

OUT

Line Regulation ⁽¹⁾

REG_(LINE)V_IN= 2.25V to 5.5V, I_OUT= 1mA, V_ADJ= V_OUT

1.5

-1

10

12

mV

Load Regulation ⁽¹⁾

REG_(LOAD)

I_OUT= 0.1mA to 150mA,

V_IN= 2.25V, V_ADJ= V_OUT

-10

-20

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2004 Semtech Corp.

2

SC553

POWER MANAGEMENT

Electrical Characteristics (Cont.)

Unless specified: V_IN= 2.25V, V_EN= V_IN, I_OUT= 100µA, C_IN= C_OUT= 1µF, T_A= 25°C. Values in bold apply over full operating ambient temperature range.

Parameter

Symbol

Conditions

Min

Typ

Max Units

OUT (Cont.)

Current Limit

Dropout Voltage⁽¹⁾⁽³⁾

I_LIM

V_D

400

mA

mV

I_OUT= 1mA

1

I_OUT= 50mA

50

65

75

mV

I

_OUT= 100mA

100

150

125

155

190

230

I_OUT= 150mA

EN

Enable Input Threshold

V_IH

V_IL

I_EN

2.25V ≤ V_IN≤ 6.5V

0V ≤ V_EN≤ V_IN

1.6

V

0.4

Enable Input Bias Current ⁽²⁾

Over Temperature Protection

High Trip Level

-0.5

0

+0.5

µA

T_HI

150

15

°C

Hysteresis

T_HYST

Notes:

(1) Low duty cycle pulse testing with Kelvin connections required.

(2) Guaranteed by design.

(3) V_OUT= 3.3V. Defined as the input to output differential at which the output voltage drops 100mV below the value

measured at a differential of 1V. Not measurable on outputs set below 2.25V due to minimum V_INconstraints. See

Typical Characteristics for typical dropout voltage at other output voltage settings.

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2004 Semtech Corp.

3

SC553

POWER MANAGEMENT

Pin Configuration

Ordering Information

Part Number⁽¹⁾

Package

SOT-23-5

Top View

SC553ISKTR

SC553ISKTRT⁽²⁾

Notes:

(1) Only available in tape and reel packaging. A reel

contains 3000 devices.

SOT-23-5L

(2) Lead free product. This product is fully WEEE and

RoHS compliant.

Pin Descriptions

Pin #

Pin Name

Pin Function

Input pin.

1

2

3

4

IN

GND

EN

Ground pin. Can be used for heatsinking if needed.

Active high enable pin. Connect to IN if not being used.

ADJ

Adjust pin. Connecting this pinto anexternal resistor divider (see Typical ApplicationCircuit

on page 1) sets V_OUTto:

R1

R2





V_OUT= 1.250 • 1+









5

OUT

Regulator output, sourcing up to 150mA.

Block Diagram

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2004 Semtech Corp.

4

SC553

POWER MANAGEMENT

Marking Information

Top Mark

Bottom Mark

yyww

553

yyww = Datecode (Example: 0108)

Applications Information

Theory Of Operation

Component Selection - General

The SC553 is intended for applications where very low Output capacitor - Semtech recommends a minimum

dropout voltage, low supply current and low output noise capacitance of 1µF at the output with an equivalent

are critical. It provides a very simple, low cost solution series resistance (ESR) of < 1Ω over temperature. While

that uses very little pcb real estate. Only two external the SC553 has been designed to be used with ceramic

capacitors are required for operation.

capacitors, it does not have to be used with ceramic

capacitors, allowing the designer a choice. Increasing the

The SC553 contains a bandgap reference trimmed for bulk capacitance will further reduce output noise and

optimal temperature coefficient which is fed into the improve the overall transient response.

inverting input of an error amplifier. The output voltage

of the regulator is divided down externally using a Input capacitor - Semtech recommends the use of a

resistor divider and compared to the bandgap voltage 1µF ceramic capacitor at the input. This allows for the

via the adjust pin (ADJ). The error amplifier drives the device being some distance from any bulk capacitance

gate of a low R_DS(ON)P-channel MOSFET pass device to on the rail. Additionally, input droop due to load transients

maintain V_OUTsuch that V_ADJ= V_REF.

is reduced, improving overall load transient response.

An active high enable pin (EN) allows the regulator to be External voltage selection resistors - the use of 1%

shut down. Pulling this pin low causes the device to resistors, and designing for a current flow ≥ 10µA is

enter a very low power shutdown mode, where it will draw recommended to ensure a well regulated output (thus

typically 0.1µA from the input supply.

R2 ≤ 125kΩ). The output voltage (referring to Figure 1

below) will be:

The regulator has its own current limit circuitry to

ensure that the output current will not damage the

device during output short, overload or start-up. The

current limit is guaranteed to be greater than 400mA to

allow fast charging of the output capacitor and high

initial currents for DSP initialization.

R1

R2







V_OUT= 1.250 • 1+







U1

IN

SC553

OUT

1

5

4

VOUT

VIN

3

C1

R1

R2

C2

The SC553 includes thermal shutdown circuitry to turn

off the device if T_Jexceeds 150°C (typical), with the

device remaining off until T_Jdrops by 15°C (typical).

Reverse battery protection circuitry ensures that the

device cannot be damaged if the input supply is

accidentally reversed, limiting the reverse current to less

than 1.5mA.

EN

ADJ

1uF

GND

2

1uF

Figure 1

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2004 Semtech Corp.

5

SC553

POWER MANAGEMENT

Applications Information (Cont.)

Thermal Considerations

Layout Considerations

The worst-case power dissipation for this part is given While layout for linear devices is generally not as critical

by:

as for a switching application, careful attention to detail

will ensure reliable operation.

P

=

(

V

_IN(MAX)− V_OUT(MIN)

)

•I_OUT(MAX)+ V_IN(MAX)•I_Q(MAX)

(1)

D(MAX)

1) Attaching the part to a larger copper footprint will

enable better heat transfer from the device, especially

on PCBs where there are internal ground and power

planes.

For all practical purposes, equation (1) can be reduced

to the following expression:

(2)

2) Place the input and output capacitors close to the

device for optimal transient response and device

behaviour.

Looking at a typical application, 3.3V to 2.8V at 150mA:

V_IN(MAX)= 3.3 + 5% = 3.465V

V_OUT(MIN)= 2.8V - 2% = 2.744V

I_OUT= 150mA

3) While the external resistor divider does not need to be

close to the device, care should be taken to avoid routing

the connections next to any lines carrying large amounts

of noise. The simplest solution is to place these resistors

close to the device and routing the top of R1 to the load

if not adjacent to the part.

T_A= 85°C

Inserting these values into equation (2) gives us:

4) Connect all ground connections directly to the ground

plane. If there is no ground plane, connect to a common

local ground point before connecting to board ground.

Using this figure, we can calculate the maximum thermal

impedance allowable to maintain T_J≤ 125°C:

Typical Characteristics

(

T_J(MAX)− T_A(MAX)

)

=

(

125 − 85

)

Dropout Voltage vs. Output Voltage

vs. Output Current

θ_JA(MAX)

=

= 370°C/ W

P_D(MAX)

0.108

250

T_A= 25°C

With the standard SOT-23-5 Land Pattern shown at the

end of this datasheet, and minimum trace widths, the

thermal impedance junction to ambient for SC553 is

256°C/W. Thus no additional heatsinking is required for

this example.

225

200

Top to bottom:

175

150

125

100

75

I_OUT= 150mA

I

_OUT= 100mA

I_OUT= 50mA

The junction temperature can be reduced further (or

higher power dissipation can be allowed) by the use of

larger trace widths and connecting PCB copper to the

GND pin (pin 2), which connects directly to the device

substrate. Adding approximately one square inch of PCB

copper to pin 2 will reduce θ_JAto approximately

130°C/W and T_J(MAX)for the example above to

approximately 100°C. The use of multi layer boards with

internal ground/power planes will lower the junction

temperature and improve overall output voltage

accuracy.

50

25

0

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

V_OUT(V)

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2004 Semtech Corp.

6

SC553

POWER MANAGEMENT

Outline Drawing - SOT-23-5

Land Pattern - SOT-23-5

This land pattern is for reference only. Consult your

manufacturing group to ensure you meet your

company’s manufacturability guidelines.

Contact Information

Semtech Corporation

Power Management Products Division

200 Flynn Road, Camarillo, CA 93012

Phone: (805)498-2111 FAX (805)498-3804

www.semtech.com

2004 Semtech Corp.

7

型号:	SC55150KR
是否无铅：	不含铅
是否Rohs认证：	符合
生命周期：	Active
Reach Compliance Code：	unknown
ECCN代码：	EAR99
HTS代码：	8504.50.80.00
风险等级：	5.24
构造：	Flame Retardant
直流电阻：	0.6 Ω
标称电感 (L)：	15 µH
电感器应用：	POWER INDUCTOR
电感器类型：	GENERAL PURPOSE INDUCTOR
引线直径：	0.6 mm
引线长度：	30 mm
制造商序列号：	SC55
功能数量：	1
端子数量：	2
最高工作温度：	125 °C
最低工作温度：	-55 °C
封装直径：	5.2 mm
封装长度：	11.4 mm
封装形式：	Axial
包装方法：	TR
最小质量因数（标称电感时）：	55
最大额定电流：	0.6 A
自谐振频率：	55 MHz
系列：	SC55
形状/尺寸说明：	TUBULAR PACKAGE
屏蔽：	YES
表面贴装：	NO
端子位置：	AXIAL
端子形状：	WIRE
测试频率：	2.5 MHz
容差：	10%
Base Number Matches：	1

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