L9945 datasheet(118/151 Pages) STMICROELECTRONICS

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Figure 24. NDIS structure

3.3 V

Input structure

Output structure

IPD

GND

NDIS

To logic

NMOS

3.3 V

GND

VDD5 UV/OV

GADG1003170815PS

Table 31. NDIS OV protection electrical characteristics

Symbol

Parameter

Test condition

Min.

Typ.

Max.

Unit

VNDIS_OV

NDIS OV disable threshold

Low Side ON

0.8

1.0

tNDIS_OV

NDIS OV deglitch filter time

2.2

2.5

2.7

µs

tNDIS_OV_react

NDIS OV Comparator reaction time

100

700

6.1.2

VDD5 Overvoltage/Undervoltage

VDD5 is internally monitored to detect overvoltage/undervoltage conditions:

•

In case VDD5 ≥ VVDD5_OV, an internal OV disable is generated after the filter time tVDD5_OV. Such an event

is latched in OV_DIS_LATCH, cleared on SPI readout. In case of overvoltage all outputs except channel 7

and 8 are actively turned off until the next SPI diagnostic readout. Overvoltage comparator status can be

monitored reading OV_VDD5_STATE bit via SPI. If the comparator output goes high due to a transient

overvoltage, the OV_VDD5_LATCH is set, even if the filter time tVDD5_OV hasn't expired. This latch is

cleared on SPI readout and doesn't imply an output disable.

•

In case VPOR ≤ VDD5 ≤ VVDD5_UV, an internal UV disable is generated after the filter time tVDD5_UV1. Such

an event is latched in UV_DIS_LATCH, cleared on SPI readout. Once UV disable is activated it will stay

active at least for tVDD5_UV1 after UV condition disappears. In case of undervoltage all outputs except

channel 7 and 8 are actively turned off. If UV condition disappears, outputs are automatically re-engaged.

Undervoltage comparator output can be monitored by reading UV_DIS_STATE via SPI.

In case VDD5 ≤ VPOR an internal POR is generated and the device is reset. Such an event is latched in

n_POR_LATCH and can be cleared via SPI readout.

Note:

Refer to Table 8 for the electrical characteristics and the parameters regarding VDD5 overvoltage and

undervoltage detection.

When configured as H-Bridge, channels 7 and 8 are handled like other channels and are disabled in case of

VDD5 UV/OV.

L9945

Disable sources

DS12275 - Rev 8

page 118/151

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