Datasheet
LM5025
CONTROLLER
FB
OUT_A
OUT_B
-3V
INB
IN_A
IN_REF
IN
INB
LM5110-1
OUT_B
OUT_A
V
CC
V
EE
V
EE
OUT
V
EE
IN_REF
V
OUT
V
IN
+5V
Dual Supply
utilizing negative
Output voltage
Drive
LM5112
V
CC
+10V
UVLO
IN_REF
IN_REF
LM5112
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SNVS234B –SEPTEMBER 2004–REVISED APRIL 2006
Simplified Application Block Diagram
Figure 16. Simplified Application Block Diagram
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 considerably. 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 optimize current capability over a
wide output voltage and operating temperature range. The bipolar device provides high peak current at the
critical Miller plateau region of the MOSFET V
GS
, while the MOS device provides rail-to-rail output swing. The
totem pole output drives the MOSFET gate between the gate drive supply voltage V
CC
and the power ground
potential at the V
EE
pin.
The control inputs of the driver are high impedance CMOS buffers with TTL compatible threshold voltages. The
negative 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 provide the option of single supply or split supply configurations. When driving the MOSFET gates
from a single positive supply, the IN_REF and V
EE
pins are both connected to the power ground.
The isolated input and output stage grounds provide the capability to drive the MOSFET to a negative V
GS
voltage for a more robust and reliable off state. In split supply configuration, the IN_REF pin is connected to the
ground of the controller which drives the LM5112 inputs. The V
EE
pin is 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 difference between V
CC
and IN_REF or between V
CC
and V
EE
is 14V.
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