L9380_08 STMICROELECTRONICS [STMicroelectronics], L9380_08 Datasheet - Page 9

• Manufacturer Part Number: L9380_08
• Description: Triple high-side MOSFET driver
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L9380
4
Functional description
The triple high-side Power-MOS Driver features all necessary control and protection
functions to switch on three Power-MOS transistors operating as High-Side switches in
automotive electronic control units. The key application field is relays replacement in
systems where high current loads, usually motors with nominal currents of about 40 A
connected to ground, has to be switched.
A high signal at the EN pin enables all three channels. With enable low gates are clamped to
ground. In this condition the gate sink current is higher than the specified 3 mA. An enable
low signal makes also a reset of the timer.
A low signal at the inputs switch on the gates of the external MOS. A short circuit at the input
leads to permanent activation of the concerned channel. In this case the device can be
disabled with the enable pin. The charge pump loading is not influenced due to the enable
input.
An external N-channel MOS driver in high side configuration needs a gate driving voltage
higher than V
capacitors and one external charge storage capacitor C
The charge pump is dimensioned to load a capacitor CCP of 33 nF in less than 20 ms up to
8V above V
the decay of the charge pump voltage down to that value where no significant influence on
the application occurs.
The necessary charging time for C
control signals.
As a consequence the lower gate to source voltage can cause a higher drop across the
Power-MOS and get into overload condition. In this case the overload protection timer will
start.
After the protection time the concerned channel will be switched off. Channel 3 is not
equipped with an overload protection. The same situation can occur due to a discharge of
the storage capacitor caused by the gate short to ground. The gate driver that is supplied
from the pin CP, which is the charge pump output, has a sink and source current capability
of 3 mA. For a short-circuit of the load (source to ground) the L9380 has no gate to source
limitation. The gate source protection must be done externally.
Channel 1 and 2 provide drain to source voltage sensing possibility with programmable
shut-off delay when the activation threshold was exceeded.
This threshold V
resistor is determined by the programming resistor R
also the charge and discharge current of the timer capacitor C
threshold V
DSmin
S
. The value of C
S
. It is generated by means of a charge pump with integrated charge transfer
DSmin
and the timer shut off delay time T
is set by the external resistor R
CP
depends on the input capacitance of the external MOS and
V
CP
DSmin
T
has to be respected in the sequence of the input
off
= 4.4 C
=
V
PR
T
R
⎛
⎜
⎝
off
----------- -
R
PR
R
D
PR
PR
. The bias current flowing through this
can be calculated:
D
. This external resistor R
CP
⎞
⎟
⎠
.
CT
. The drain to source
Functional description
PR
defines
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