Datasheet
SLVS132F − NOVEMBER 1995 − REVISED OCTOBER 2004
14
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APPLICATION INFORMATION
The TPS2811, TPS2812 and TPS2813 circuits each contain one regulator and two MOSFET drivers. The regulator
can be used to limit V
CC
to between 10 V and 13 V for a range of input voltages from 14 V to 40 V, while providing
up to 20 mA of dc drive. The TPS2814 and TPS2815 both contain two drivers, each of which has two inputs. The
TPS2811 has inverting drivers, the TPS2812 has noninverting drivers, and the TPS2813 has one inverting and one
noninverting driver. The TPS2814 is a dual 2-input AND driver with one inverting input on each driver, and the
TPS2815 is a dual 2-input NAND driver. These MOSFET drivers are capable of supplying up to 2.1 A or sinking up
to 1.9 A (see Figures 15 and 16) of instantaneous current to n-channel or p-channel MOSFETs. The TPS2811 family
of MOSFET drivers have very fast switching times combined with very short propagation delays. These features
enhance the operation of today’s high-frequency circuits.
The CMOS input circuit has a positive threshold of approximately 2/3 of V
CC
, with a negative threshold of 1/3 of V
CC
,
and a very high input impedance in the range of 10
9
Ω. Noise immunity is also very high because of the Schmidt trigger
switching. In addition, the design is such that the normal shoot-through current in CMOS (when the input is biased
halfway between V
CC
and ground) is limited to less than 6 mA. The limited shoot-through is evident in the graphs in
Figures 17 and 18. The input stage shown in the functional block diagram better illustrates the way the front end works.
The circuitry of the device is such that regardless of the rise and/or fall time of the input signal, the output signal will
always have a fast transition speed; this basically isolates the waveforms at the input from the output. Therefore, the
specified switching times are not affected by the slopes of the input waveforms.
The basic driver portion of the circuits operate over a supply voltage range of 4 V to 14 V with a maximum bias current
of 5 µA. Each driver consists of a CMOS input and a buffered output with a 2-A instantaneous drive capability. They
have propagation delays of less than 30 ns and rise and fall times of less than 20 ns each. Placing a 0.1-µF ceramic
capacitor between V
CC
and ground is recommended; this will supply the instantaneous current needed by the fast
switching and high current surges of the driver when it is driving a MOSFET.
The output circuit is also shown in the functional block diagram. This driver uses a unique combination of a bipolar
transistor in parallel with a MOSFET for the ability to swing from V
CC
to ground while providing 2 A of instantaneous
driver current. This unique parallel combination of bipolar and MOSFET output transistors provides the drive required
at V
CC
and ground to guarantee turn-off of even low-threshold MOSFETs. Typical bipolar-only output devices don’t
easily approach V
CC
or ground.
The regulator, included in the TPS2811, TPS2812 and TPS2813, has an input voltage range of 14 V to 40 V. It
produces an output voltage of 10 V to 13 V and is capable of supplying from 0 to 20 mA of output current. In grounded
source applications, this extends the overall circuit operation to 40 V by clamping the driver supply voltage (V
CC
) to
a safe level for both the driver and the MOSFET gate. The bias current for full operation is a maximum of 150 µA.
A 0.1-µF capacitor connected between the regulator output and ground is required to ensure stability. For transient
response, an additional 4.7-µF electrolytic capacitor on the output and a 0.1-µF ceramic capacitor on the input will
optimize the performance of this circuit. When the regulator is not in use, it can be left open at both the input and the
output, or the input can be shorted to the output and tied to either the V
CC
or the ground pin of the chip.