L9826

4 Functional Description

CD00002120

11/17

Outputs Control Tables :

Figure 5.

Output control register structure

4.3

Power outputs characteristics

for flyback current, outputs short circuit protection and diagnostics

For output currents flowing into the circuit the output voltages are limited. The typical value of

this voltage is 50V. This function allows that the flyback current of a inductive load recirculates

into the circuit; the flyback energy is absorbed in the chip.

Output short circuit protection for outputs 3 to 8 (dedicated for loads without inrush current):

when the output current exceeds the short circuit threshold, the corresponding output overload

latch is set and the output is switched off immediately.

Output short circuit protection for outputs 1 and 2 (dedicated for loads with inrush current, as

lamps): when the load current would exceed the short circuit limit value, the corresponding

output goes in a current regulation mode.

The output current is determined by the output characteristics and the output voltage depends

on the load resistance. In this mode high power is dissipated in the output transistor and its

temperature increases rapidly. When the power transistor temperature exceeds the thermal

shutdown threshold, the overload latch is set and the corresponding output switched off.

For the load diagnostic in output off condition each output features a diagnostic current sink, typ

60

µA.

Table 5.

Outputs 1, 2:

Outputs 3 to 8:

NON1, 2

1001

SPI-bit 1, 2

0011

SPI-bit 3 ... 8

0

1

Output 1, 2

off

on

on

on

Output 3 ... 8

off

on

Q2

Q4

Q6

Q8

Q1

Q3

Q5

Q7

MSB

LSB

Control-bit output 7

Control-bit output 5

Control-bit output 3

Control-bit output 1

Control-bit output 8

Control-bit output 6

Control-bit output 4

Control-bit output 2