Buck/Boost Regulating

Charge Pump in µMAX

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5

Typical Operating Characteristics (continued)

NAME

FUNCTION

1

POK

Open-Drain Power-OK Output. POK is high impedance when output voltage is in regulation. POK sinks current

Ground POK or leave unconnected if not used. POK is high impedance in shutdown.

2

SHDN

Shutdown Input. Drive high for normal operation; drive low for shutdown mode. OUT is high impedance in

shutdown.

PIN

3, 4

IN

Input Supply. Connect both pins together and bypass to GND with a ceramic capacitor (see Capacitor

Selection section).

5

GND

Ground. Connect GND to PGND with a short trace.

9

OUT

Power Output. Bypass to GND with an output filter capacitor.

8

CXP

Positive Terminal of the Charge-Pump Transfer Capacitor

7

CXN

Negative Terminal of the Charge-Pump Transfer Capacitor

6

PGND

Power Ground. Charge-pump current flows through this pin.

10

FB

Dual-Mode Feedback. Connect FB to GND for 3.3V output. Connect to an external resistor divider to adjust

the output voltage from 2.5V to 5.5V.

Pin Description

1

2

-4.2V

-2.5V

100

µs/div

LINE-TRANSIENT RESPONSE

Ω

1

2

3

4

500

µs/div

TURN-ON/OFF RESPONSE

Ω

1

2

3

4

500

µs/div

TURN-ON/OFF RESPONSE

Ω