L9659 datasheet(20/51 Pages) STMICROELECTRONICS

20 / 51 page

Functional description

L9659

20/51

Doc ID 022048 Rev 2

3.2.3

Reference resistor

IREF pin shall be connected to VDD supply through a resistor, RIREF. When the L9659

detects the resistor on IREF pin is larger than RIREF_H or smaller than RIREF_L, it goes

into a reset condition. All outputs are disabled and all internal registers are reset to their

default conditions.

3.2.4

Loss of ground

GND

When the GND pin is disconnected from PC-board ground, the L9659 goes in reset

condition. All outputs are disabled and all internal registers are reset to their default

conditions.

GND0-GND7

A loss of power-ground (GND0 – GND7) pin/s disables the respective low side driver/s on

SQLx. However, the high side driver of the respective channel will still be able to be turned

on. Thus under the scenario where the low side is shorted to ground the L9659 will be able

to provide the programmed firing current for the specified time.

An open GNDx connection on any channel has no affect on the other channels. An open

GNDx condition will be detected using the low side MOS diagnostics.

AGND

The AGND pin is a reference for AOUT pin. When AGND loses its connection, the voltage

on AOUT pin is pulledup to VDD voltage and L9659 goes in reset condition. All outputs are

disabled and all internal register are reset to their default conditions.

3.2.5

VRESx capacitance

To ensure all diagnostics function properly a typical capacitor of equal to or greater than

68nF is required close to the firing supply pins. Thus minimum of 4 capacitors are required

with one placed close to the VRES0 and VRES1 pins and a second capacitor will be close

to the VRES2 and VRES3 pins and a third capacitor will be close to the VRES4 and VRES5

pins and a forth capacitor will be close to the VRES6 and VRES7 pins.

3.2.6

Supply voltages

The primary current sources for the different functions of the ASIC are as follows:

●

VRESx - Firing currents along with HSS and HS FET diagnostic currents

●

VSDIAG - Squib resistance and HSS diagnostics

●

VDD will be used for all internal functions as well as short to battery/ground and high

squib resistance diagnostics.

3.2.7

Ground connections

GND pin (6) is not connected internally to other ground pins (AGND or power ground

GNDx). A ground plane is needed to directly connect the GND pin. This ground plane needs

to be isolated from the high current ground for the squib drivers to prevent voltage shifts.

AGND pin should be connected to ground plane too to minimize drop versus ground

reference of ADC that capture AOUT voltage.

L9659 датащи(PDF) 20 Page - STMicroelectronics

L9659 датащи(HTML) 20 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

датащи скачать

ссылки URL