Rainbow-electronics MAX8758 Manual do Utilizador descarregar pdf (Página 9)

MAX8758

Step-Up Regulator with Switch Control and

Operational Amplifier for TFT LCD

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Pin Description

PIN NAME FUNCTION

1 GND Analog Ground

2 GON

Internal High-Voltage-Switch Common Connection. GON is the output of the high-voltage-switch-

control block. GON is internally pulled to PGND through a 1kΩ resistor in shutdown. See the High-

Voltage Switch Control section for details.

3 CTL H i g h- V ol tag e, S w i tch- C ontr ol Bl ock Ti m i ng P i n. S ee the H i g h- V ol tag e S w i tch C ontr ol secti on for d etai l s.

4 DLP

High-Voltage, Switch-Control Block Delay Pin. Connect a capacitor from DLP to GND to set the delay

time. A 5µA current source charges C

DLP

. DLP is internally pulled to GND by a resistor in shutdown.

See the High-Voltage Switch Control section for details.

5 THR

GON Falling Regulation Adjustment Pin. Connect THR to the center of a resistive voltage-divider

between LDO or OUT and GND to adjust the V

GON

falling regulation level. The actual regulation level

is 10 x V

THR

. See the High-Voltage Switch Control section for details.

6 SUPB Operational Amplifier Supply Input. Bypass SUPB to GND with a 0.1µF capacitor.

7OUTB Operational Amplifier Output

8 NEGB Operational Amplifier Inverting Input

9 POSB Operational Amplifier Noninverting Input

10 N.C. No Connection. Not internally connected.

11 LDO

5V Internal Linear Regulator Output. This regulator powers all internal circuitry except the operational

amplifier. Bypass LDO to GND with a 0.22µF or greater ceramic capacitor.

12 OUT

Internal Linear Regulator Supply Pin. OUT is the supply input of the internal 5V linear regulator.

Connect OUT directly to the output of the step-up regulator.

13 I.C. Internally Connected. Make no connection to this pin.

14 SS

Soft-Start Control Pin. Connect a capacitor between SS and GND to set the soft-start period of the

step-up regulator. See the Bootstrapping and Soft-Start section for details.

15 COMP

Error Amplifier Compensation Pin. See the Step-Up Regulator Loop Compensation section for details.

16 FREQ

Frequency-Select Pin. Connect FREQ to GND for 600kHz operation, and connect FREQ to IN for

1.2MHz operation.

17 IN

Supply Pin. Bypass IN to GND with a 1µF ceramic capacitor. Place the capacitor close to the IN pin.

18 LX

Switching Node. LX is the drain of the internal power MOSFET. Connect the inductor and the Schottky

diode to LX and minimize trace area for low EMI.

19 SHDN

Shutdown Control Pin. Pull SHDN low to turn off the step-up regulator, the operational amplifier, and

the switch control block.

20 FB

Feedback Pin. The FB regulation point is 1.24V (typ). Connect FB to the center of a resistive voltage-

divider between the step-up regulator output and GND to set the step-up regulator output voltage.

Place the divider close to the FB pin.

21 PGND Power Ground

22 MODE

High-Voltage, Switch-Control Block-Mode Selection Timing-Adjustment Pin. See the High-Voltage

Switch Control section for details. MODE is high impedance when it is connected to LDO. MODE is

internally pulled down by a 1kΩ resistor during UVLO, when V

DLP

< 0.5 x V

LDO

, or in shutdown.

23 DRN

High-Voltage, Switch-Control Input. DRN is the drain of the internal high-voltage p-channel MOSFET

connected to GON.

24 SRC

High-Voltage Switch-Control Input. SRC is the source of the internal high-voltage p-channel MOSFET.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 ... 19 20

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