L9822E

Pin description

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2.1

Pin description

Table 2.

Pin function

PowerSO20

pin #

Multiwatt15

pin #

Name

Function

1, 10, 11, 20

8

GND

Device ground.

This ground applies for the logic circuits as well as the

power output stages.

29

SO

Serial output.

This pin is the serial output from the shift register and it is

tri-stated when CE is high. A high for a data bit on this pin

indicates that the particular output is high. A low on this

pin for a data bit indicates that the output is low.

Comparing the serial output bits with the previous serial

input bits the external microcontroller implements the

diagnostic data supplied by the L9822E.

310

Logic supply voltage - nominally 5V.

4

11

RESET

Asynchronous reset for the output stages, the parallel

latch and the shift register inside the

active low and it must not be left floating. A power on clear

function may be implemented connecting this pin to VCC

with an external resistor and to ground with an external

capacitor.

5-8, 13-16

1-4, 12-15

OUTPUT

1-7

Power output pins.

The input and output bits corresponding to 07 are sent

and received first via the SPI bus and 00 is the last. The

outputs are provided with current limiting and voltage

sense functions for fault indication and protection. The

nominal load current for these outputs is 500mA, but the

current limiting is set to a minimum of 1.05A.

The outputs also have on board clamps set at about 36V

for recirculation of inductive load current.

9,12

-

N.C.

Pins not connected.

17

5

CE

Chip enable.

Data is transferred from the shift registers to the outputs

on the rising edge of this signal. The falling edge of this

signal sets the shift register with the output voltage sense

bits coming from the output stages. The output driver for

the SO pin is enabled when this pin is low.

18

6

SCLK

Serial clock.

This pin clocks the shift register. New SO data will appear

on every rising edge of this pin and new SI data will be

latched on every SCLK’s falling edge into the shift

register.

19

7

SI

Serial input.

This pin is the serial data input. A high on this pin will

program a particular output to be OFF, while a low will

turn it ON.