MC35XS3400 Datasheet, PDF (26/45 Pages) Freescale Semiconductor, Inc – Quad High Side Switch (Quad 35mΩ)

FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSTIC FEATURES
(fault_control=0)
(OpenloadOFF=1
or ShortVpwr=1
or OV=1)
OFF
if hson=0
(fault_control=1 and OV=0)
(fault_control=0 or OV=1)
(fault_control=0)
(OpenloadON=1)
ON
if hson=1
(SC=1)
(Retry=1)
(count=16)
Autoretry
OFF
(after Retry Period and OV=0)
(OV=1)
(OpenloadOFF=1
or ShortVpwr=1
or OV=1)
(Retry=1)
=> count=count+1
(fault_control=0)
(OpenloadOFF=1
or ShortVpwr=1
or OV=1)
Latched
OFF
(SC=1)
(OpenloadON=1)
Autoretry
ON
if hson=1
Figure 12. Auto-retry State Machine
AUTO-RETRY
The auto-retry circuitry is used to reactivate the output(s)
automatically in case of over-current or over-temperature or
under-voltage failure conditions to provide a high availability
of the load.
Auto-retry feature is available in Fault mode. It is activated
in case of internal retry signal is set to logic [1]:
retry[x] = OC[x] or OT[x] or UV.
The feature retries to switch-on the output(s) after one
auto-retry period (t_AUTO) with a limitation in term of number of
occurrence (16 for each output). The counter of retry
occurrences is reset in case of Fail-safe to Normal or Normal
to Fail-safe mode transitions. At each auto-retry, the over-
current detection will be set to default values in order to
sustain the inrush current.
The Figure 12 describes the auto-retry state machine.
DIAGNOSTIC
Output Shorted to VPWR Fault
The 35XS3400 incorporates output shorted to VPWR
detection circuitry in OFF state. Output shorted to VPWR fault
is detected if output voltage is higher than V_OSD(THRES) and
reported as a fault condition when the output is disabled
(OFF). The output shorted to VPWR fault is latched into the
status register after the internal gate voltage is pulled low
enough to turn OFF the output. The OS[0:3] and
OL_OFF[0:3] fault bits are set in the status register and FS
pin reports in real time the fault. If the output shorted to
VPWR fault is removed, the status register will be cleared
after reading the register.
The open output shorted to VPWR protection can be
disabled through SPI (OS_DIS[0:3] bit).
Open-Load Faults
The 35XS3400 incorporates three dedicated open-load
detection circuitries on the output to detect in OFF and in ON
state.
Open-load Detection In Off State
The OFF output open-load fault is detected when the
output voltage is higher than V_OLD(THRES) pulled up with
internal current source (I_OLD(OFF)) and reported as a fault
condition when the output is disabled (OFF). The OFF Output
open-load fault is latched into the status register or when the
internal gate voltage is pulled low enough to turn OFF the
output. The OL_OFF[0:3] fault bit is set in the status register.
If the open load fault is removed (FS output pin goes to high),
the status register will be cleared after reading the register.
The OFF output open-load protection can be disabled
through SPI (OLOFF_DIS[0:3] bit).
35XS3400
26
Analog Integrated Circuit Device Data
Freescale Semiconductor