TC1426 Microchip Technology, TC1426 Datasheet - Page 6

• Manufacturer Part Number: TC1426
• Description: (TC1426 - TC1428) 1.2A Dual High-Speed MOSFET Drivers
• Manufacturer: Microchip Technology

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TC1426/TC1427/TC1428
3.0
3.1
Large currents are required to charge and discharge
capacitive loads quickly. For example, charging a
1000pF load to 16V in 25nsec requires a 0.8A current
from the device’s power supply.
To guarantee low supply impedance over a wide
frequency range, a parallel capacitor combination is
recommended for supply bypassing. Low-inductance
ceramic MLC capacitors with short lead lengths
(<0.5-in.) should be used. A 1.0µF film capacitor in
parallel with one or two 0.1µF ceramic MLC capacitors
normally provides adequate bypassing.
3.2
The TC1426 and TC1428 contain inverting drivers.
Individual ground returns for the input and output
circuits or a ground plane should be used. This will
reduce negative feedback that causes degradation in
switching speed characteristics.
FIGURE 3-1:
DS21393B-page 6
Test Circuit
Output
Input
V
+5V
DD
0V
0V
Input
APPLICATIONS INFORMATION
SUPPLY BYPASSING
GROUNDING
10%
90%
t
D1
(1/2 TC1428)
10%
V
TC1426
DD
INVERTING DRIVER
SWITCHING TIME
t
1
2
F
= 16V
1µF
MKS-2
t
D2
C
L
90%
0.1µF MLC
Output
= 1000pF
t
R
10%
90%
3.3
The input voltage level changes the no-load or
quiescent supply current. The N-channel MOSFET
input stage transistor drives a 2.5mA current source
load. With a logic "1" input, the maximum quiescent
supply current is 9mA. Logic "0" input level signals
reduce quiescent current to 500µA maximum. Unused
driver inputs must be connected to V
Minimum power dissipation occurs for logic "0" inputs
for the TC1426/TC1427/TC1428.
The drivers are designed with 100mV of hysteresis.
This provides clean transitions and minimizes output
stage current spiking when changing states. Input
voltage thresholds are approximately 1.5V, making a
logic "1" input any voltage greater than 1.5V up to V
Input current is less than 1µA over this range.
The TC1426/TC1427/TC1428 may be directly driven
by the TL494, SG1526/27, TC38C42, TC170 and
similar switch-mode power supply integrated circuits.
FIGURE 3-2:
Test Circuit
Output
Input
V
+5V
DD
0V
0V
INPUT STAGE
Input
10%
t
D1
(1/2 TC1428)
90%
NONINVERTING DRIVER
SWITCHING TIME
V
TC1427
DD
 2002 Microchip Technology Inc.
10%
1
2
= 16V
t
R
1µF
WIMA
MKS-2
t
90%
D2
C
L
0.1µF MLC
DD
Output
= 1000pF
10%
or GND.
90%
DD
t
F
.