L9945 datasheet(138/151 Pages) STMICROELECTRONICS

138 / 151 page

Figure 39. Fast charge/discharge currents for OL detection: (left) OL detection on LS; (right) OL detection on HS

Vout

Settling

counter

LS OFF Diagnostics

VLVT

VOL

tDIAG

LS ON

Fast charge

VOUT_OL

LS OFF (no OL)

LS ON

LS OFF (OL)

Vout

Settling

counter

HS OFF Diagnostics

VLVT

VOL

tDIAG

HS ON

Fast discharge

VOUT_OL

HS OFF (no OL)

HS ON

HS OFF (OL)

GADG1303171134PS

The table below reports the electrical characteristics of the fast charge/discharge current generators.

Table 48. Fast charge/discharge current generator electrical characteristics

Symbol

Parameter

Min.

Max.

Unit

IFAST_CHG

Vout node fast charge current used in case of LS NMOS

2.4

3.8

IFAST_DIS_P

Vout node fast discharge current used in case of HS PMOS

IFAST_DIS_N

Vout node fast discharge current used in case of HS NMOS

Note:

Vout corresponds to DRNx pin for LS NMOS and HS PMOS configurations, while it's SNGPx pin for HS NMOS

configuration.

6.5

Silent diagnostic pulses for static loads

L9945 features ON/OFF diagnostic pulses of fixed duration for monitoring channels that are in a steady state. Two

type of pulses are available:

•

OFF pulse: turns off the selected channel for a tPULSE_OFF interval. To be used for OL and STG/STB

detection. It is effective only if Tdiag < 100 µs.

•

ON pulse: turns on the selected channel for a tPULSE_ON interval. To be used for OC detection. It is effective

only if Tblank_oc < 80 µs.

Once a diagnostic pulse is over, the output control is released and channel can be driven either by NONx pins or

SPI (as programmed).

Diagnostic pulses can be sent by programming the DIAG_ON_PULSE_xx and DIAG_OFF_PULSE_xx bit in the

COMMAND 9 frame. Pulse requests are latched and are reset once pulse execution is completed.

For each channel:

•

A diagnostic pulse request must not be sent until the previous one is completed. If a pulse request incomes

when pulse latches are still set, it will be ignored.

L9945

Silent diagnostic pulses for static loads

DS12275 - Rev 8

page 138/151

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