LM5112-SD National Semiconductor, LM5112-SD Datasheet - Page 7

• Manufacturer Part Number: LM5112-SD
• Description: Tiny 7A MOSFET Gate Driver
• Manufacturer: National Semiconductor

Detailed Operating Description
The LM5112 is a high speed , high peak current (7A) single
channel MOSFET driver. The high peak output current of the
LM5112 will switch power MOSFET’s on and off with short
rise and fall times, thereby reducing switching losses con-
siderably. The LM5112 includes both inverting and non-
inverting inputs that give the user flexibility to drive the
MOSFET with either active low or active high logic signals.
The driver output stage consists of a compound structure
with MOS and bipolar transistor operating in parallel to opti-
mize current capability over a wide output voltage and oper-
ating temperature range. The bipolar device provides high
peak current at the critical Miller plateau region of the MOS-
FET V
swing. The totem pole output drives the MOSFET gate be-
tween the gate drive supply voltage V
ground potential at the V
The control inputs of the driver are high impedance CMOS
buffers with TTL compatible threshold voltages. The nega-
tive supply of the input buffer is connected to the input
ground pin IN_REF. An internal level shifting circuit connects
the logic input buffers to the totem pole output drivers. The
level shift circuit and separate input/output ground pins pro-
vide the option of single supply or split supply configurations.
GS
, while the MOS device provides rail-to-rail output
EE
pin.
FIGURE 2. Simplified Application Block Diagram
CC
and the power
7
When driving the MOSFET gates from a single positive
supply, the IN_REF and V
power ground.
The isolated input and output stage grounds provide the
capability to drive the MOSFET to a negative V
a more robust and reliable off state. In split supply configu-
ration, the IN_REF pin is connected to the ground of the
controller which drives the LM5112 inputs. The V
connected to a negative bias supply that can range from the
IN_REF potential to as low as 14 V below the Vcc gate drive
supply. For reliable operation, the maximum voltage differ-
ence between V
14V.
The minimum recommended operating voltage between Vcc
and IN_REF is 3.5V. An Under Voltage Lock Out (UVLO)
circuit is included in the LM5112 which senses the voltage
difference between V
When the V
the driver is disabled and the output pin is held in the low
state. The UVLO hysteresis prevents chattering during
brown-out conditions; the driver will resume normal opera-
tion when the V
3.0V.
CC
to IN_REF voltage difference falls below 2.8V
CC
CC
and IN_REF or between V
to IN_REF differential voltage exceeds
CC
and the input ground pin, IN_REF.
EE
pins are both connected to the
20066803
CC
GS
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and V
voltage for
EE
pin is
EE
is