P7/21

Rev. C, Sep 2005

ML1565

Pin Description

Pin1

COMP1

Pin2

FB1

Pin3

PGNDA

Pin4

LXSD

Pin5

INSD

Pin6

ONSD

Pin7

COMPSD

Pin8

FBSD

Pin9

ON1

Pin10

ON2

Pin11

ON3

Pin12

ONSU

Pin13

REF

Pin14

FBSU

Pin15

COMPSU

Auxiliary Controller 1 Compensation Node. Connect a series RC from COMP1 To GND to compensate

the control loop. COMP1 is actively driven to GND in shutdown and thermal limit.

Auxiliary Controller 1 Feedback Input. For 5V output, short FBSEL1 to GND and connect FB1 to the

output voltage. For other output voltages, connect FBSEL1 to OUTSU and connect a resistive voltage

divider from the step-up converter output to FB1 to GND. The FB1 feedback threshold is then 1.25V.

This pin is high impedance in shutdown.

Power Ground. Connect PGNDA and PGNDB together and to GND with short trace as close to the IC

as possible.

Step-Down Converter Power-Switching Node. Connect LXSD to the step-down converter inductor.

LXSD is the drain of the P-channel switch and N-channel synchronous rectifier. LXSD is high

impedance in shutdown.

Step-Down Converter Input. INSD can connect to OUTSU, effectively making OUTSD a buck-boost

output from the battery. Bypass to GND with a 1µF ceramic capacitor if connected to OUTSU. INSD

may also be connected to the battery, but should not exceed OUTSU by more than a Schottky diode

forward voltage. Bypass INSD with a 10µF ceramic capacitor when connecting to the battery input. A

10kΩ internal resistance connects OUTSU and INSD.

Step-Down Converter On/Off Control Input. Drive ONSD high to turn on the step-down converter. This

pin has an internal 330kΩ pulldown resistor. ONSD does not start until OUTSU is in regulation.

Step-Down Converter Compensation Node. Connect a series RC from COMPSD to GND to

compensate the control loop. COMPSD is pulled to GND in normal shutdown and during thermal

shutdown (see the Step-Down Compensation section).

Step-Down Converter Feedback Input. For a 1.5V output, short FBSELSD to GND and connect FBSD

to OUTSD. For other voltages, short FBSELSD to OUTSU and connect a resistive voltage-divider

from OUTSD to FBSD to GND. The FBSD feedback threshold is 1.25V. This pin is high impedance in

shutdown.

Auxiliary Controller 1 On/Off control Input Drive ON1 high to turn on. This pin has an internal 330kΩ

pulldown resistor. ON1 cannot start until OUTSU is in regulation.

Auxiliary Controller 2 On/Off control Input Drive ON2 high to turn on. This pin has an internal 330kΩ

pulldown resistor. ON2 cannot start until OUTSU is in regulation.

Auxiliary Controller 3 On/Off control Input Drive ON3 high to turn on. This pin has an internal 330kΩ

pulldown resistor. ON3 cannot start until OUTSU is in regulation.

Step-up Converter On/Off Control. Drive ONSU high to turn on the step-up converter. All other control

pins are locked out until 2ms after the step-up output has reached its final value. This pin has an

internal 330kΩ resistance to GND.

Reference Output. Bypass REF to GND with a 0.1µF or greater capacitor. The maximum allowed load

on REF is 200µA. REF is actively pulled to GND when all converters are shut down.

Step-Up Converter Feedback Input. To regulate OUTSU to 3.35V, connect FBSELSU to GND. FBSU

may be connected to OUTSU or GND. For other output voltages, connect FBSELSU to OUTSU and

connect a resistive voltage-divider from OUTSU to FBSU to GND. The FBSU feedback threshold is

1.25V. This pin is high impedance in shutdown.

Step-Up Converter Compensation Node. Connect a series RC from COMPSU to GND to compensate

the control loop. COMPSD is pulled to GND in normal shutdown and during thermal shutdown (see

the Step-Down Compensation section).