YB1520ST25原理图各脚功能电路原理芯片引脚定义引脚图及功能-中国IC网-芯三七

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Description

Features

The YB1520 is a step-up DC-DC converter;

operates as current source to drive up to 9

white LEDs in series or 30 white LEDs in

parallel/series configuration. Series connecting

of the LEDs provides identical LED currents

resulting in uniform brightness and eliminating

the need for ballast resistors. The light intensity

of these LEDs is proportional to the current

passing through them. The YB1520 switches at

a fixed frequency of 700KHz, allowing the use

of tiny, low profile inductors and capacitors to

minimize footprint and cost in space

consideration applications for cellular phone

backlighting or other hand held equipment.

The YB1520 can drive up to 9 white LEDs from

a single Li-Ion battery and drive up to 30 white

LEDs from a 5V. The wide input voltage range

from 2.7V to 16V is ideal for portable and

automotive (5V/12V) applications with higher

conversion efficiency. To control LED

brightness, the LED current can be pulsed by

applying a PWM (pulse width modulated) signal

with a frequency range of 100Hz to 50KHz to

the CTRL pin.

Built-in internal switch

Adjustable output voltage up to 35V

2.7V to 16V input range

<1uA shutdown current

High efficiency

Drives up to 30 white LEDs in

Parallel/series

Over voltage protection

Small 5-Lead SOT-23 package

Applications

LCD Display Module

White LED Backlighting

PDAs, GPS terminals

Digital Cameras

Cellular Phone

Electronic Books

Portable Applications

YB1520 has integrated Over Voltage Protection

that prevents damage to the device in case of a

high impedance output due to faulty LED or

open circuit caused by abnormal conditions.

Typical Application Circuit

Figure 1: Typical Application Circuit

YB1520 MRev.1.2

www.yobon.com.tw

1

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Pin Configuration

Pin Description

Table 1

NAME

Description

Switching Pin. This is the collector of the internal NPN power

SW

switch. Connect to inductor and diode. Minimize the metal

trace area connected to this pin to reduce EMI.

1

GND

FB

Ground Pin. Connect directly to local ground plane.

2

3

Feedback Pin. Reference voltage is 200mV. Connect LEDs

and a resistor at this pin. LED current is determined by the

resistance and CTRL voltage.

Shutdown Pin and Dimming Control pin.

VCTRL > 1.8V generates full-scale LED current

VCTRL < 0.4V chip is off

CTRL

VIN

4

5

Switching from 0.4V to 2.0V, PWM duty cycle controls the LED

current

Input Supply Pin. Bypass this pin with a capacitor as close to

the device as possible

Ordering Information

Order Number

Supplied as

Package Marking

YB1520ST25

3000 units Tape & Reel

Y52M

YB1520 MRev.1.2

www.yobon.com.tw

2

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Absolute Maximum Ratings

Recommended Operating Conditions

Operating Temperature (note 3)................ –40°C~85°C

Vin..........................................................................20V

SW Voltage............................................................36V Supply Voltage............................................. 2.5V~16V

FB Voltage ...............................................................5V SW Voltage............................................................30V

CTRL Voltage...........................................................5V

Maximum Junction Temp, TJ (not 2)...................150°C

Lead Temperature (Soldering 10 sec) ................300°C

Thermal Resistance............................................195°C

Electricity Characteristics

(TA=25°C, Vin=3.3V, Cin=1uF Cout=10uF unless otherwise noted)

Symbol

Function Parameter

Input Voltage Range

Not Switching

Test Conditions

Min

2.7

Typ Max Units

Vin

16

V

IQ

Vfb = 0.3V

1.2

1.5

0.3

1.7

mA

(Quiescent

Current)

CTRL = 0V

Shutdown

1

uA

Iout=20mA,Vout=12.5V

Circuit of Figure 1

VFB

Feedback Voltage

180

850

200

220

950

mV

ICL

100% Duty Cycle

40% Duty Cycle

900

600

mA

Switch Current Limit

ILIM

Vfb=200mV

IB

FB Pin Bias Current

Switching Frequency

2

10

20

uA

FRSW

680

700

720

KHz

DTMX

DTMN

VSAT

ILKG

Maximum Duty Cycle

Minimum Duty Cycle

Switch Vcesat

85

25

%

20

At Isw = 200mA

Ctrl = 0.3V

120

1

mV

μA

Switch Leakage Current

Full On

Full Off

Ctrl = 2V

1.7

0.2

20

1.8

0.3

V

VCTRL for Full LED

Current

VCTL

ICTL

CTRL Pin Bias Current

μA

OVP

Over Voltage Protection

Thermal Resistance

34

V

θJA

220

°C/W

Note:

Absolute maximum ratings are limits beyond which damage to the device may occur. The maximum allowable power dissipation is a

function of maximum function temperature, TJ(max), the junction to ambient thermal resistance, θJA , and the ambient temperature.

The maximum allowable, power dissipation at any ambient temperature is calculated using: PD(MAX)= [TJ(max)-TA]/θJA . Exceeding

the maximum allowable power dissipation will cause excessive die temperature. All limits at temperature extremes are guaranteed via

correlation using standard statistical methods

YB1520 MRev.1.2

www.yobon.com.tw

3

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Typical Performance Characteristics

EFFICIENCY

3S5P Output Ripple

89%

88%

87%

86%

85%

84%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

4

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Efficiency

3S6P Output Ripple

90%

88%

86%

84%

82%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

5

YB1520

High Power Step-up DC-DC Converter, White LED Driver

EFFICIENCY

3S7P Output Ripple

90%

88%

86%

84%

82%

80%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

6

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Efficiency

3S8P Output Ripple

90%

88%

86%

84%

82%

80%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

7

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Efficiency

3S9P Output Ripple

88%

86%

84%

82%

80%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

8

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Efficiency

3S10P Output Ripple

88%

86%

84%

82%

80%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

9

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Efficiency

9S Output Ripple

84%

82%

80%

78%

76%

3

3.5

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

10

YB1520

High Power Step-up DC-DC Converter, White LED Driver

EFFICIENCY

8S3P Output Ripple

85%

84%

83%

82%

81%

80%

79%

4

4.5

5

5.5

6

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

11

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Efficiency

9S3P Output Ripple

86%

84%

82%

80%

78%

4

4.5

5

5.5

6

6.5

7

VIN(V)

YB1520 MRev.1.2

www.yobon.com.tw

12

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Typical Performance Characteristics

Drive Switch Saturation Voltage(Vcesat)

Switching Frequency

730

725

720

715

710

705

700

695

160

140

120

100

80

60

0

50

100

150

200

250

300

0

20

40

60

80

100

120

Switch Current(mA)

TEMPERATURE (°C)

Supply current test

Switch Leakage Current

1

0.9

0.8

0.7

0.6

0.5

2.5

2

1.5

1

0.5

2

4

6

8

10

Vin(V)

12

14

16

2

4

6

8

10 12 14 16

Vin (V)

YB1520 MRev.1.2

www.yobon.com.tw

13

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Switching Waveform

YB1520 MRev.1.2

www.yobon.com.tw

14

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Functional Block

Figure 3: YB1520 Block Diagram

Operation

The YB1520 uses a constant frequency,

current mode control scheme to regulate

the output LED current. Its operation can

be understood by referring to the block

diagram in Figure 3. At the start of each

oscillator cycle, a voltage proportional to

the switch current is added to a ramp

output and the resulting sum is fed into the

positive terminal of the PWM comparator.

When this voltage exceeds the level of the

comparator negative input, the peak current

has been reached, and the SR latch is

reset and turns off the power switch. The

voltage at the negative input of the

comparator comes from the output of the

error amplifier. The error amplifier sets the

correct peak current level to keep the

output in regulation. If the error amplifier’s

output increases, more current is delivered

to the output; if it decreases, less current is

delivered.

Application Information

Inrush Current

The maximum switch current is limited to

about 900 mA by the chip Typically, A larger

Cout will increase the duration of high

current.

However, when Vin is first

connected, an even larger current can flow

into Cout. This occurs when the SW pin is

open circuit and the Cout voltage changes

from 0V to Vin in a few microseconds.

Because the duration of this large current is

short, it will usually not cause problems. If

this current is not desirable, an external

soft-start circuit can be added to

significantly reduce this inrush current.

YB1520 MRev.1.2

www.yobon.com.tw

15

YB1520

High Power Step-up DC-DC Converter, White LED Driver

PWM Signal(1KHz,2Vp-p,duty 20%~80%)

LED Current and Dimming Control

The LED’s current is set by a resistor

connected at FB pin to GND using:

200mV

Over Voltage Protection

The YB1520 has an internal over voltage

protection circuit which also acts as an

open-circuit protection. In the cases of

open circuit or the LEDs failure, the LEDs

are disconnected from the circuit, and the

feedback voltage will be zero. The YB1520

will then switch to a high duty cycle

resulting in a high output voltage, which

may cause SW pin voltage to exceed its

maximum 34V rating. The YB1520 will

shutdown automatically until input condition

changes to bring it out of the shutdown

mode.

I_LED

=

R_LED

The maximum LED current set initially can

be reduced by pulse width modulating the

CTRL. A better approach is to adjust the

feedback voltage for dimming control.

Either a DC level signal or a filtered PWM

signal can be used to control the LED

current as illustrated in Figure 4 and Figure

5 respectively. Using the above different

scheme, the LED current can be controlled

from 20% to 80% to its maximum value.

Inductor Selection

A 47uH inductor is recommended for most

applications to drive more than 9 LEDs in

serials and 33uH inductor is recommended

for drive 30 LEDs in serials/parallel.

Although small size and high efficiency are

major concerns, the inductor should have

low core losses at 1MHz and low DCR

(copper wire resistance).

Figure 4. Dimming Control Using a DC Voltage

Diode Selection

To maintain high efficiency, the average

current rating of the Schottky diode should

be large than the peak inductor current, IPK.

Schottky diode with a low forward drop and

fast switching speeds are ideal for increase

efficiency in portable application. Choose a

reverse breakdown of the Schottky diode

large than the output voltage.

Figure 5. Dimming Control Using a Filtered

YB1520 MRev.1.2

www.yobon.com.tw

16

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Capacitor Selection

Choose low ESR capacitors for the output

to minimize output voltage ripple. Multilayer

capacitors are a good choice for this as well.

A 47uF capacitor is sufficient for most

applications. For additional bypassing, a

100nF ceramic capacitor can be used to

shunt high frequency ripple on the input.

The input bypass capacitor Cin, as shown

in Figure 1, must be placed close to the IC.

This will reduce copper trace resistance

which affects input voltage ripple of the IC.

For additional input voltage filtering, a

100nF bypass capacitor can be placed in

parallel with Cin to shunt any high

frequency noise to ground. The output

capacitor, Cout, should also be placed

close to the IC. Any copper trace

connections for the Cout capacitor can

increase the series resistance, which

directly effect output voltage ripple.

The feedback network, resister R2 should

be kept close to the FB pin to minimize

copper trace connections that can inject

noise into the system. The ground

connection for the feedback resistor

network should connect directly to an

analog ground plane. The analog ground

plane should tie directly to the GND pin. If

no analog ground plane is available, the

ground connection for the feedback

network should tie directly to the GND pin.

Trace connections made to the inductor

and Schottky diode should be minimized to

reduce power dissipation and increase

overall efficiency.

YB1520 MRev.1.2

www.yobon.com.tw

17

YB1520

High Power Step-up DC-DC Converter, White LED Driver

Package Description

All the contains in this datasheet are not assuming any responsibility for use of any

circuitry described no circuit patent license are implied and Yobon reserves the right at

any time without notice to change said circuitry and specifications.

Yobon Inc. would like to receive your feedback with your recommends and suggestions

that is always welcome and with our appreciations.

YB1520 MRev.1.2

www.yobon.com.tw

18

型号:	YB1520ST25
生命周期：	Contact Manufacturer
IHS 制造商：	YOBON TECHNOLOGIES INC
Reach Compliance Code：	unknown
风险等级：	5.76
接口集成电路类型：	LED DISPLAY DRIVER
Base Number Matches：	1

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