Triple-Output TFT-LCD

DC-DC Converters

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7

Typical Operating Characteristics (continued)

Pin Description

5V/div

2V

10V

0

500mA/div

MAIN BOOST STARTUP WAVEFORM

MAX1748/8726 toc16

1ms/div

2V/div

0

0

5V/div

2V

10V

0

500mA/div

MAIN BOOST STARTUP

WAVEFORM WITH LOAD

MAX1748/8726 toc17

1ms/div

Ω (200mA)

2V/div

0

0

5V/div

5V/div

10V/div

MAX1748 POWER-UP SEQUENCING

MAX1748/8726 toc18

2ms/div

2V/div

PIN

NAME

FUNCTION

1

RDY

Active-Low, Open-Drain Output. Indicates all outputs are ready. The on-resistance is 125

Ω (typ).

2FB

Main Boost Regulator Feedback Input. Regulates to 1.248V nominal. Connect feedback resistive

divider to analog ground (GND).

3

INTG

Main Boost Integrator Output. If used, connect 470pF to analog ground (GND). To disable integrator,

connect to REF.

4IN

Supply Input. +2.7V to +5.5V input range. Bypass with a 0.1µF capacitor between IN and GND, as

close to the pins as possible.

5

GND

Analog Ground. Connect to power ground (PGND) underneath the IC.

6

REF

Internal Reference Bypass Terminal. Connect a 0.22µF capacitor from this terminal to analog ground

(GND). External load capability to 50µA.

7

FBP

Positive Charge-Pump Regulator Feedback Input. Regulates to 1.25V nominal. Connect feedback

resistive divider to analog ground (GND).

5V/div

5V/div

10V/div

MAX8726 POWER-UP SEQUENCING

MAX1748/8726 toc19

4ms/div

5V/div