iC-MFN
8-FOLD FAIL-SAFE N-FET DRIVER
Rev A2, Page 2/13
DESCRIPTION
iC-MFN is a monolithically integrated, 8-channel level
adjustment device which drives N-channel FETs.
The internal circuit blocks have been designed in
such a way that with single errors, such as open
pins (VB, VBR, GND, GNDR) or the short-circuiting
of two outputs, iC-MFN’s output stages switch to a
predefined, safe low state. Externally connected N-
channel FET are thus shut down safely in the event
of a single error.
The inputs of the eight channels consist of a Schmitt
trigger with a pull-down current source and are com-
patible with TTL and CMOS levels and are voltage-
proof up to 40 V. The eight channels have a current-
limited push-pull output stage and a pull-down resis-
tor at the output. The hi-level at one of the inputs
EN5, EN10 or ENFS defines the output hi-level and
enables the outputs. The output hi-level is disabled
with the lo-level at all inputs EN5, EN10 and ENFS or
with the hi-level at more than one input.
iC-MFN monitors the supply voltage at VB and VBR
pin and the voltages at the two ground pins GND and
GNDR. Both power supply pins VB and VBR and
both pins GND and GNDR must be connected to-
gether externally in order to guarantee the safe low
state of the output stages in the event of error.
Should the supply voltage at VB undershoot a prede-
fined threshold, the voltage monitor causes the out-
puts to be actively tied to GND via the lowside tran-
sistors. If the ground potential ceases to be applied
to GND, the outputs are tied to GNDR by pull-down
resistors.
If the connection between the ground potential and
the GND pin is disrupted, the highside and lowside
transistors of the output stages are shut down and
the outputs tied to GNDR via the pull-down resistors.
If on the other hand the connection between ground
potential and the GNDR pin is disrupted, only the
output stage highside transistors are shut down; the
outputs are then actively tied to GND via the lowside
transistors.
Pull-down currents provide the safe lo-level at open
inputs IN1. . . 8, EN5, EN10 and ENFS. The pull-
down currents have two stages in order to minimize
power dissipation with enhanced noise immunity.
The status of the device is indicated with the Open-
Drain pin NOK and can be used for system diagnos-
tics.
Temperature monitoring protects the device from too
high power dissipation.
The device is protected against destruction by ESD.
ICHAUS [ IC-HAUS GMBH ]
