33888 Datasheet, PDF (27/40 Pages) Freescale Semiconductor, Inc – Quad High-Side and Octal Low-Side Switch for Automotive

FUNCTIONAL DEVICE OPERATION
PROTECTION AND DIAGNOSTIC FEATURES
33888
HIGH = Fault
+
–
Digital
MOSFET ON
V_PWR
R_L
OUT
+
–
Analog
V_REF
V_THRES ^VOFD(THRES)LS
2.0 V–4.0 V
Figure 10. Low-Side Short Circuit Detection and Analog Current Limit
UNDERVOLTAGE SHUTDOWN REQUIREMENTS
All outputs turn off at some battery voltage below 6.0 V;
For the A version, the low side shutdown at a lower value,
V_PWRUV. however, as long as the level stays above 5.0 V, the
internal logic states within the device are designed to be
sustained. This ensures that when the battery level then rises
above 6.0 V, the device will return to the state that it was in
prior to the excursion between 5.0 V and 6.0 V (assuming
that there was no SPI communication or direct input changes
during the event). If the battery voltage falls to a level below
5.0 V, then the internal logic is re initialized and the device is
then in the default state upon the return of levels in excess of
6.0 V.
OUTPUT VOLTAGE CLAMPING
Each output has an internal clamp to provide protection
and dissipate the energy stored in inductive loads. Each
clamp independently limits the drain-to-source voltage to the
range specified in the Power Outputs section of Table 5,
Static Electrical Characteristics beginning on page 10. Also
see Figure 11.
If the VPWR supply is disconnected, no issue exists for
resistive or capacitive loads, but additional protection circuitry
is required for the device to support a battery disconnect for
an inductive load connected to HS pins.
Drain-Source
Clamp Voltage
(V_CL = 53 V)
Drain Voltage
Drain Current
(I_D = 0.5 A)
Drain-Source
ON Voltage
(V_DS(ON))
GND
Current
Area (I_A)
Clamp Energy
(E_J = I_A x V_CL x t)
VPWR
Time
Figure 11. Low-Side Output Voltage Clamping
Analog Integrated Circuit Device Data
Freescale Semiconductor
33888
27