Functional description

L9826

12/19

Doc ID 7214 Rev 10

5

Functional description

5.1

General

The L9826 is an 8-channel low-side driver assembled in SO20 package. Its 8-bit SPI serial

interface is designed to control all the outputs and to provide their diagnosis. Channels 1

and 2 are controlled either via SPI or via parallel through the inputs pins NON1 and NON2.

Diagnostic recognizes operative fault conditions: open load, short circuits to GND or to VB

and overcurrent.Thermal shutdown for outputs 1 and 2 is available as well the output voltage

clamp which is essential in case of working with inductive loads.

The reset feature is an OR function of the external reset nRes and the internal reset

generate during the undervoltage condition

5.2

Output stage control

5.2.1

Via parallel, only for output 1 and 2

This is valid only for Outputs 1 and 2 which are controlled through the dedicated inputs

NON1 and NON2 (both active low) which are internally configured as pull-up (see Figure 3).

This is to guarantee that the outputs are off in case of inputs open.

A further feature is the possibility to drive these outputs through a PWM signal

independently by SPI commands.

Reset signal is common for all the eight channels and it is active low. After an external reset

condition (that means NRES pin switched from low to high) to drive outputs 1 and 2 through

the parallel input (NON1 and NON2) it is necessary to disable the parallel input itself

(NON1, NON2 high) and then subsequently to drive the outputs 1 and 2 at the logic state

desiderated through NON1 and NON2. The duration of the command (T) as reported in the

Figure 4 should be at less in the order of 100 nSecond.

In the next Figure 4 is shown this behavior and in the next Table 7 is summarized the

scenario of parallel/series commands.

Figure 4.

Parallel control for output 1 and 2 (Example for Power-on)

Table 7.

Outputs control tables

Outputs 1, 2:

Outputs 3 to 8:

NON1, 2

1

0

0

1

-

-

-

SPI-bit 1, 2

0

0

1

1

SPI-bit 3 ... 8

0

1

Output 1, 2

off

on

on

on

Output 3 ... 8

off

on