FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSTIC FEATURES
Table 7. Device behavior in case of Under-voltage
Quad High Side
UV Enable
Switch
UV Disable
IN[0:3] = 0
(Falling or
UV Disable
IN_x*** = 1
(Falling or
UV Enable
IN[0:3] = 0
UV Enable
IN_x*** = 1
UV Enable
IN_x*** = 1
State
IN[0:3] = 0
(VPWR Battery
(Falling VPWR) (Rising VPWR) (Falling VPWR) (Rising VPWR)
Voltage)∗∗
Rising VPWR) Rising VPWR)
VPWR > VPWRUV Output State
FS State
OFF
OFF
ON
1
OFF
OFF
1
ON
1
1
0
1
0
1
SPI Fault Register
UVF Bit
1 until next read
0
0 (falling)
1 until next
read (rising)
0 (falling)
1 until next
read (rising)
VPWRUV > VPWR Output State
OFF
OFF
OFF
OFF
OFF
ON
1
> UVPOR
FS State
0
1
0
1
0
1
0
1
1
1
SPI Fault Register
1
UVF Bit
UVPOR > VPWR > Output State
OFF
1
OFF
1
OFF
1
OFF
1
OFF
1
ON
1
2.5V∗
FS State
SPI Fault Register 1 until next read 1 until next read 1 until next read 1 until next read 1 until next read 1 until next read
UVF Bit
2.5V > VPWR > 0V Output State
FS State
OFF
1
OFF
1
OFF
1
OFF
1
OFF
1
OFF
1
SPI Fault Register 1 until next read 1 until next read 1 until next read 1 until next read 1 until next read 1 until next read
UVF Bit
Comments
UV fault is
not latched
UV fault is
not latched
UV fault
is latched
∗ = Typical value; not guaranteed
∗∗ = While VDD remains within specified range.
*** = IN_x is equivalent to IN_x direct input or IN_spi_s SPI input.
enhanced to keep the junction temperature less than 150°C.
The ON resistance of the output is fairly similar to that in the
Normal mode. No additional passive components are
required except on VDD.
OPEN LOAD FAULT (NON-LATCHING)
The 33874 incorporates open load detection circuitry on
the output. Output open load fault (OLF) is detected and
reported as a fault condition when the output is disabled
(OFF). The open load fault is detected and latched into the
status register after the internal gate voltage is pulled low
enough to turn OFF the output. The OLF fault bit is set in the
status register. If the open load fault is removed, the status
register will be cleared after reading the register.
GROUND DISCONNECT PROTECTION
In the event the 33874 ground is disconnected from load
ground, the device protects itself and safely turns OFF the
output regardless of the state of the output at the time of
disconnection. A 10KΩ resistor needs to be added between
the wake pin and the rest of the circuitry in order to ensure
that the device turns off in case of ground disconnect and to
prevent this pin to exceed its maximum ratings.
The open load protection can be disabled through SPI
(bit OL_DIS). It is recommended to disable open load
circuitry in case of a permanent disconnected load.
Current limit resistors in the digital input lines protect the
digital supply against excessive current (10kΩ typical).
REVERSE BATTERY
The output survives the application of reverse voltage as
low as -16V. Under these conditions, the output’s gate is
33874
Analog Integrated Circuit Device Data
Freescale Semiconductor
21
FREESCALE [ Freescale ]
