Datasheet

Analog Integrated Circuit Device Data
Freescale Semiconductor 39
10XSC425
6.3.3.3 OpenLoad Detection In Off State
The OFF output OpenLoad 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 OpenLoad fault is latched
into the status register, or when the internal gate voltage is pulled low enough to turn the output OFF. The OL_OFF[0:3] fault bit
is set in the status register. If the OpenLoad fault is removed (FSB output pin goes to high), the status register will be cleared
after reading the register.
The OFF output OpenLoad protection can be disabled through the SPI (OLOFF_DIS[0:3] bit).
6.3.3.4 OpenLoad Detection In On State
The ON output OpenLoad current thresholds can be chosen by the SPI to detect a standard bulb or LED (OLLED[0:3] bit set to
logic [1]). In the case where the load current drops below the defined current threshold, the OLON bit is set to logic [1], the output
stays ON, and FSB is not disturbed.
6.3.3.5 OpenLoad Detection In On State For Led
OpenLoad for LEDs only (OLLED[0:3] set to logic [1]) is detected periodically at each t
OLLED
(fully-on, D[6:0]=7F)
.
To detect
OLLED in a fully on state, the output must be ON at least t
OLLED.
To delatch the diagnosis, the condition should be removed and a SPI read operation is needed (OL_ON[0:3] bit). The ON output
OpenLoad protection can be disabled through the SPI (OLON_DIS[0:3] bit).
6.3.4 Analog Current Recopy and Temperature Feedbacks
The CSNS pin is an analog output reporting a current proportional to the designed output current, or a voltage proportional to the
temperature of the GND flag (pin #14). The routing is SPI programmable (TEMP_en, CSNS_en, CSNS_s[1,0] and CSNS_ratio_s
bits).
In case the current recopy is active, the CSNS output delivers current only during the ON time of the output switch without
overshoot. The maximum current is 2.0
mA (typical). The typical value of the external CSNS resistor connected to ground is
2.5 k.
The current recopy is not active in Fail-safe mode.
6.3.4.1 Temperature Prewarning Detection
In Normal mode, the 10XSC425 provides a temperature prewarning reported via the SPI, in case the temperature of the GND
flag is higher than T
OTWAR
. This diagnosis (OTW bit set to [1]) is latched in the SPI DIAGR0 register. To delatch, a SPI read
command is needed.
6.3.5 Active Clamp ON VPWR
The device provides an active gate clamp circuit, to limit the maximum transient VPWR voltage at VPWR
(CLAMP)
. In case of
an overload on an output the corresponding output is turned off, which leads to high voltage at VPWR with an inductive VPWR
line. When VPWR voltage exceeds the VPWR
(CLAMP)
threshold, the turn-off on the corresponding output is deactivated and all
HS[0:3] outputs are switched ON automatically, to demagnetize the inductive Battery line.
For long battery line (> 10 meters, corresponding to 10 µH of parasitic inductance) between the battery and the device, the smart
high side switch output may be damaged, in cases of short-circuit due to unexpected behavior of internal active gate clamp
circuitry. It is essential not to exceed the maximum rating on the VPWR pin (41
V).
6.3.6 Reverse Battery ON VPWR
The output survives the application of reverse voltage as low as -18 V. Under these conditions, the ON resistance of the output
is two times higher than the typical ohmic value in forward mode. No additional passive components are required except on the
V
DD
current path.