MP1529 – FIXED FREQUENCY STEP-UP CONVERTER LCD BACKLIGHT PLUS FLASH

MP1529 Rev. 1.0

www.MonolithicPower.com

3

11/23/2005

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TM

Parameter

Symbol

Condition

Min

Typ

Max

Units

Current Sense to COMP

Transconductance

200

µA/V

Oscillation Frequency

1.0

1.2

1.4

MHz

SW Maximum Duty Cycle

95

%

EN1, EN2 High Voltage

1.4

V

EN1, EN2 Low Voltage

0.3

V

EN1, EN2 Turn-Off Delay to

Shutdown

(4)

10

ms

EN1 PWM Frequency

(4)

1

50

KHz

Soft-Start Period

(4)

10

ms

Thermal Shutdown

160

°C

Note:

4) The soft-start timer and the PWM timer are the same timer with the same timing.

PIN FUNCTIONS

Pin # Name Description

1

EN1 Enable Input. See Table 1 for PWM serial interface usage. EN1 has an internal pull-down of 1.2MΩ.

2

EN2 Enable Input. See Table 1 for PWM serial interface usage. EN2 has an internal pull-down of 1.2MΩ.

3

COMP

Control Loop Compensation Node. COMP is the output of the internal transconductance amplifier.

Connect a series resistor-capacitor network between COMP and GND to compensate the control

loop.

4

SS

Soft-Start Capacitor Pin. Doubles as the PWM timer.

5

LED3

Number 3 LED String Current Control Input. Connect the bottom (Cathode) of the Number 3 LED

string to LED3. This string is the flash string.

6

GND Analog Ground. (Connect the Exposed Pad to Pin 6)

7

LED2

Number 2 LED String Current Control Input. Connect the bottom (Cathode) of the Number 2 LED

string to LED2. This string is the backlight string.

8

LED1

Number 1 LED String Current Control Input. Connect the bottom (Cathode) of the Number 1 LED

string to LED1. This string is the backlight string.

9

ISET1

Current Control Input. Connect a resistor between ISET1 and GND to set the backlight LED string

current up to 30mA.

10

ISET2

Current Control Input. Connect a resistor between ISET2 and GND to set the flash LED string

preview current up to 150mA.

11

ISET3

Current Control Input. Connect a resistor between ISET3 and GND to set the flash LED string current

up to 150mA.

12

OUT

Output Voltage Sensing Input. When the OUT pin voltage exceeds the overvoltage threshold, the

MP1529 automatically shuts down to prevent internal damage. Connect OUT to the output of the

step-up converter.

14

SW

Switch Output. SW is the drain of the internal N-Channel MOSFET switch. Connect the power

inductor between SW and the input source, and connect the output rectifier between SW and the

output to form the step-up converter.

16

IN

Input Supply Pin. Must be locally bypassed.

13,15 PGND Power Ground.