YB1521芯片引脚定义引脚图及功能IC贸易商引脚图技术参数-中国IC网-芯三七

YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Description

Features

The YB1521 is a step-up DC-DC converter ꢀ 2.5V to 5.5V Input Voltage Range

which operating as current source to drive ꢀ Built In Power MOSFET

up 45 white LEDs (3S15P) in parallel / ꢀ Drive Up to 15V @400mA at 5V Vin

series configuration from a 5V system rail. ꢀ Less than 1µA Shutdown Current

Series connecting of LEDs provides ꢀ Up to 94% efficiency

identical LED currents resulting in uniform ꢀ Over Voltage Protection@18V

brightness and eliminating the need for ꢀ UVLO, Thermal Shutdown

ballast resistors. The light intensity of these ꢀ Internal 1.6A Current Limit

LEDs is proportional to the current passing ꢀ 200mv Low Reference Voltage

through them. The YB1521 is a fixed ꢀ Built In Soft Start

frequency of 1.3MHz, allowing the use of ꢀ PWM Dimming

tiny low profile inductors and capacitors to ꢀ SOT23-5 Package

minimize footprint and cost in space ꢀ Green Package (RoHS) Available

consideration applications for cellular

Applications

phone backlighting or other hand held

equipment.

ꢀ Cellular and Smart Phones

ꢀ Handheld Computers and PDAs

The wide input voltage range from 2.5V to

ꢀ Small LCD Displays

5.5V is idea for portable applications with

ꢀ GPS Terminals

higher conversion efficiency. To control

ꢀ MP3 Players

LED brightness, the LED current can be

ꢀ Digital Still and Video Cameras

pulsed by applying a PWM signal with a

ꢀ Electronic Books

frequency which is typically 50 KHz to the

EN pin.

Typical Application Circuit

Efficiency vs. Input Voltage

100

I_OUT=100mA

I_OUT=180mA

L=10 H

μ

D1

Schottk

90

80

70

60

50

L 1

VI = 4.5~5.5V

6.8u

4.7u/2

V

4.7u/1

V

I

S

15 strings

YB1521

E

…

O

GN

F

4

4.5

5

5.5

6

R 1

INPUT VOLTAGE(V)

Figure 1: Typical Application Circuit

Figure 2: Efficiency

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Pin Configuration

Figure 3: Pin Configuration

Pin Assignment & Description

Table1

1

NAME

SW

Description

Switching Pin. This is the drain of internal power MOSFET

switch. Connect the power inductor and output rectifier to SW.

2

GND

Ground pin. Connect directly to local ground plane.

Feedback Pin. Reference voltage is 200mV. Connect LEDs and

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

resistance and FB voltage.

3

FB

Shutdown Pin and Dimming Control Pin. PWM duty cycle

controls the LED current.

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

the device as possible.

4

5

EN

IN

Ordering Information

Table2

Order Number

Package Type

SOT23-5

Supplied As

Package Marking

YB1521ST25

3000 Units Tape & Reel

Y521

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Absolute Maximum Ratings (Note 1)

Recommended Operating Conditions

(Note 2)

V_INto GND............................-0.3V to 6V

V_ENto GND...........................-0.3V to 6V

V_SWto GND.........................-0.3V to 18V

Junction Temperature ................... 150℃

Storage Temperature .......-55℃ to 150℃

Lead Temperature......................... 300℃

ESD HBM ........................................ 3KV

ESD MM .........................................250V

Supply Voltage V_IN............... 2.5V to 5.5V

Operating Temperature .......-40℃ to 85℃

Output Voltage ......................... 0V to 15V

Thermal Information

(Note 3)

θ_JA............................................ 220℃ / W

Note:

1. Exceeding these ratings may damage the device.

2. The device is not guaranteed to function outside of its operating conditions.

3. θ_JAis measured in free air at T_A= 25℃ on a low effective thermal conductivity board.

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Electrical Characteristics

Table4

(V_IN=5V, V_EN=5V, T_A=25°C, unless otherwise noted.)

Parameters

Symbol

V_IN

Test Conditions

MIN

TYP

5

MAX Units

Input Voltage Range

Quiescent Current

Shutdown Current

2.5

5.5

0.8

1

V

I_Q

V_FB=0.3V

0.2

0.1

mA

µA

I_SD

V_EN=0V, I_OUT= 0mA

I_OUT= 260mA, V_OUT

10.5V

=

Feedback Voltage

V_FB

180

200

220

0.1

mV

FB Input Bias Current

Switch On-Resistance

Maximum Duty Cycle

Switching Frequency

EN Threshold

V_FB= 0.2V

µA

Ω

R_DSON

0.4

92

DTMX

F_SW

V_FB= 0V

85

1

%

1.3

1.5

1.6

2

MHz

V

V_ENH

V_ENL

V_ENRising, V_IN= 5V

V_ENRising, V_IN= 2.5V

1

EN Threshold

0.8

V

EN Dimming Frequency

Switch Current Limit

Under Voltage Lock Out

UVLO Hysteresis

20

1

50

1.6

KHz

A

I_ILM

UVLO

V_INRising

2.25

100

18

2.45

22

V

mV

V

Over Voltage Protection

Thermal Shutdown

OVP

T_SD

16

The Hysteresis = 20℃

℃

160

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Typical Performance Characteristics

Steady State Operation

V_IN=5V, 39 LEDS, 260mA

Startup Waveforms

V_IN=5V, 39 LEDS, 260mA

Startup Waveforms into an Open Load

V_IN=5V, 39 LEDS, 260mA

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Functional Block

Figure 4: Function Block

Operation

The YB1521 features 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 output of error

amplifier increases, more current is

delivered to the output; if it decreases, less

current is delivered.

Application Information

Inrush Current

The YB1521 has internal soft-start to limit

the amount of current through the IN pin at

startup and to also limit the amount of

overshoot on the output. The current limit is

increased by 4 steps to give a total

soft-start time of 160µs.

LED Current and Dimming Control

The LED’s current is set by a resistor

connected at FB pin to GND:

I_LED= 200mV / R₁.

The maximum LED current set initially can

YB1521 MRev.1.1

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6

YB1521

High Power Step-Up DC-DC Converter & WLED Driver

be reduced by pulse width modulating the

EN. A better approach is to adjust the

internal reference voltage for dimming

control by a logic signal illustrated in Figure

5. YB1521 contains circuitry to support this

automatically.Thetypicaldimmingfrequency is

50KHz and recommended not to lower

than 20KHz. Besides the EN dimming

control scheme, either a DC level signal or

a filtered PWM signal can be used to

control the LED current as illustrated in

Figure 6 and Figure 7 respectively. The

average current through the LEDs will

increase linearly to the duty cycle of the

c o n t r o l l i n g P W M s i g n a l .

YB1521

FB

R2

R3

20K

R1

20K

80K

0.1uF

Figure 7: Dimming Control Using a Filtered

PWM Signal

Over Voltage Protection

The YB1521 has an internal over voltage

protection circuit which also acts as an

open-circuit protection. In the case of open

circuit or the LEDs failure, the LEDs are

disconnected from the circuit, and the

feedback voltage will be zero. The YB1521

will then switch to a high duty cycle

resulting in a high output voltage, which

may cause SW voltage to exceed its

maximum 18V rating. The YB1521 will

shutdown automatically until the power is

recycled.

YB1521

EN

FB

Figure 5: PWM Dimming Control Using a Logic

Signal

Inductor Selection

A 6.8µH is recommended to drive 39 LEDs

in series/parallel. Although small size and

high efficiency are major concerns, the

inductor should have low core losses at

1.3MHz and low DCR (copper wire

resistance). A higher 10µH inductor is

recommended to improve efficiency.

YB1521

FB

R2

20K

R1

80K

VDC

Diode Selection

To maintain high efficiency, the average

current rating of the Schottky diode should

be larger than the peak inductor current.

Schottky diode with a low forward drop and

fast switching speeds are idea for

increasing efficiency in portable application.

Choose a reverse breakdown of the

Figure 6: Dimming Control Using a DC Voltage

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Schottky diode large than the output

voltage.

Capacitor Selection

Choose low ESR capacitors for the output

to minimize output voltage ripple. The

ceramic capacitor is a good choice for this

as well. A 4.7µF output capacitor is

sufficient for most applications. For

applications desire a smaller output

capacitance, a 2.2µF may be used. A 4.7µF

ceramic capacitor is recommended for the

input capacitance in the real system.

PCB Layout Consideration

Proper layout of the high frequency

switching path is critical to prevent from

noise and electromagnetic interference

problems. Due to high frequency switching,

the length and area of all the traces

connected to the switch node should be

minimized.

YB1521 MRev.1.1

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YB1521

High Power Step-Up DC-DC Converter & WLED Driver

Package Information (SOT23-5)

ꢁ The information described herein is subject to change without notice.

ꢁ Yobon does not assume any responsibility for use of any circuitry or applications described herein, nor

does it convey any patent license.

YB1521 MRev.1.1

www.yobon.com.tw

9

型号:	YB15CKG01-12-CB
Brand Name：	NKK Switches
是否无铅：	不含铅
是否Rohs认证：	符合
生命周期：	Obsolete
Reach Compliance Code：	compliant
ECCN代码：	EAR99
风险等级：	8.62
开关类型：	PUSHBUTTON SWITCH
Base Number Matches：	1

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