IMP38C/HC/42/3/4/5
P
OWER
M
ANAGEMENT
Key Features
BiCMOS Current-Mode
PWM Controllers
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384x Series Pinout with BiCMOS Technology
Zero Cross-Conduction Current by Design
1MHz Operation
65ns Maximum Current-Sense Delay
120µA Maximum Start-Up Current
1.5mA Maximum Operating Current
High Output Current Drive
– 1.0A, IMP38HC4x
– 0.5A, IMP38C4x
20V Maximum Supply Voltage
2.5V, 1%, Trimmed Error Amplifier Reference
Trimmed Oscillator Discharge Current
Pin-for-Pin Enhanced Replacements for Micrel
MIC38C/HC4x and GMT38C4x/HC4x
– 1MHz Operation
– No Cross-Conduction Current
– 50ns Current-Sense Delay
The IMP38C4x and IMP38HC4x are fixed frequency, high performance,
current-mode PWM controllers that are pin compatible with bipolar 384x
devices but feature improvements resulting from IMP’s BiCMOS
processing and circuit design. Notable among the improvements are zero
cross-conduction/shoot-through current, reduced start-up and operating
current, lower current-sense delay, higher frequency operation, full
supply voltage swing at the output and a 1% trimmed voltage reference.
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IMP38C4x and IMP38HC4x output driver stage has zero cross-conduction
current. A proprietary output state-machine monitors each output
MOSFET and guarantees by design zero cross-conduction current. This is
an industry first for 384x PWM devices.
Under-voltage lockout (UVL) performance has been improved. When
the power supply voltage is below the startup voltage, internal circuitry
puts the output into a low impedance state. The output will sink 20mA
and remain below 1.3V, well below the turn-on threshold voltage of the
external MOSFET. Even when VDD drops to zero volts, the out pin will
not rise above approximately 1.3V because the output UVLO circuit is
Block Diagrams
7 (12)
VDD
(11)
VD
+
5V
8 (14)
VREF
UVLO
Reference
–
+
–
4 (7)
1 (1)
2 (3)
6 (10)
OUT
RTCT
COMP
FB
Oscillator
T
Q
Q
–
+
2R
S
R
–
EA
1V
COMP
+
–
+
R
2.5V
Ref
(8)
PGND
Connection Notes
3 (5)
(
) Pins Are 14-Pin Devices Only
IMP38C4X, IMP38HC4X (8-Pin Devices)
50% Maximum Duty Cycle:
IMP38C44, IMP38HC44, IMP38C45, IMP38HC45
GND 5 ISNS
AGND (9)
96% Maximum Duty Cycle:
IMP38C42, IMP38HC42, IMP38C43, IMP38HC43
38C/HC_01.eps
© 2000 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP [ IMP, INC ]
