Pin connections and functions

L5988

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Pin connections and functions

Figure 1.

Pin connection ( Top view)

Table 1.

Pin functions

Name

Description

2,3,4

Unregulated DC input voltage.

1,16

Regulator output.

13,14,15

GND

Ground.

9

SYNCH

It is a Master-Slave pin. Two or more devices can be synchronized by simply connecting the

SYNCH pins together. The device operating with the highest FSW will be the Master. The

Slave devices will operate with 180° phase shift from the Master.

10

FSW

Connecting an external resistor from this pin to GND, the external frequency can be increased

up to 1 MHz. Connecting an external resistor from this pin to VREF (1.8V), the switching

frequency can be decreased down to 200 KHz. If the pin is left open, the default switching

frequency is 400 KHz. The pin voltage is 1.2V. In OVP the pin is pulled up to 3.3V (only in

latched mode).

8FB

This pin is connected to the error amplifier inverting input. Connect it to the output resistor

divider (if used) or directly to Vout. This pin is also used to sense the output voltage in order to

manage the over voltage condition.

6COMP

This pin is connected to the error amplifier output and is used to compensate the voltage

control feedback loop.

5

SS/INH

The soft-start time is programmed connecting an external capacitor from this pin and GND.

The internal current generator forces a current of 22

µA through the capacitor. When the

voltage at this pin is lower than 0.65V the device is disabled.

12

Internally regulated voltage of 1.8V. It is used to provide a voltage reference for the

multifunction pin. Filter this pin to ground with at least 1

µF ceramic cap.

7ILIM-ADJ

Connecting a resistor between this pin and GND it is possible to increase the over current

decrease the over current protection threshold.

11

S/O/U

Multifunction pin. Depending on the voltage level at the input, with this pin it is possible:

– to enable-disable the sink mode current capability after soft-start;

– to enable-disable the latch mode for the OVP;

– to set the UVLO threshold for the 3.3V BUS and 12V BUS. (2.4V and 8V respectively);

The device continuously checks the analog value present at this pin and sets the

function according with the measured voltage.

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

VOUT

VCC

VCC

VCC

SS/INH

COMP

FB

SYNCH

FSW

OUS

VREF

GND

GND

GND

VOUT

ILIM-ADJ