IMP38C4X IMP Inc, IMP38C4X Datasheet

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IMP38C4X

Manufacturer Part Number
IMP38C4X
Description
BiCMOS Current-Mode PWM Controllers
Manufacturer
IMP Inc
Datasheet
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.
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 V
not rise above approximately 1.3V because the output UVLO circuit is
© 2000 IMP, Inc.
Block Diagrams
COMP
RTCT
V
V
REF
FB
DD
7 (12)
8 (14)
4 (7)
1 (1)
2 (3)
(
+
) Pins Are 14-Pin Devices Only
2.5V
Ref
+
EA
Reference
Oscillator
DD
5V
drops to zero volts, the out pin will
2R
AGND (9)
GND 5
IMP38C/HC/42/3/4/5
IMP38C/HC/42/3/4/5
R
+
1V
ISNS
3 (5)
408-432-9100/www.impweb.com
+
+
COMP
UVLO
T
S
R
Connection Notes
IMP38C4X, IMP38HC4X (8-Pin Devices)
50% Maximum Duty Cycle:
IMP38C44, IMP38HC44, IMP38C45, IMP38HC45
96% Maximum Duty Cycle:
IMP38C42, IMP38HC42, IMP38C43, IMP38HC43
Q
Q
N 384x Series Pinout with BiCMOS Technology
N Zero Cross-Conduction Current by Design
N 1MHz Operation
N 65ns Maximum Current-Sense Delay
N 120µA Maximum Start-Up Current
N 1.5mA Maximum Operating Current
N High Output Current Drive
N 20V Maximum Supply Voltage
N 2.5V, 1%, Trimmed Error Amplifier Reference
N Trimmed Oscillator Discharge Current
N Pin-for-Pin Enhanced Replacements for Micrel
– 1.0A, IMP38HC4x
– 0.5A, IMP38C4x
MIC38C/HC4x and GMT38C4x/HC4x
Key Features
6 (10)
(11)
(8)
38C/HC_01.eps
V
OUT
PGND
D
1

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IMP38C4X Summary of contents

Page 1

... 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 ...

Page 2

... Current-sense propagation delay time is 35ns typical, 65ns maxi- mum, representing percent reduction over other 38xx implementations. Output stage drive is 0.5A for IMP38C4x devices. The high-drive IMP38HC4x family is rated at 1.0A peak current drive. Like conventional 384x controllers, the IMP38C4x and IMP38HC4x controllers use the current-mode architecture for superior load regulation, pulse-by-pulse current limiting and out- put MOSFET protection ...

Page 3

...

Page 4

Absolute Maximum Ratings V ...

Page 5

... ON Resistance, High R ON Resistance, Low IMP38HC4x ON Resistance, High R ON Resistance, Low Peak Drive Current IMP38C4x Rise Time IMP38C4x Fall Time IMP38HC4x Rise Time IMP38HC4x Fall Time Shoot-through Current Undervoltage Lockout Start Threshold Minimum Operating Voltage Pulse Width Modulator Maximum Duty Cycle ...

Page 6

... This minimizes heat dissipation, increases efficiency and enhances reliability. Oscillator Operation Two external components, RT and CT, set the switching frequency. With V = 14V 10k and CT = 3.3nF, nominal switching CC frequency is 50kHz. IMP38C4x IMP38HC4x 1. frequency Ω ...

Page 7

... S Q – UVL R COMP Protection + Connection Notes IMP38C4X, IMP38HC4X (8-Pin Devices) 50% Maximum Duty Cycle: IMP38C44, IMP38HC44, IMP38C45, IMP38HC45 96% Maximum Duty Cycle: IMP38C42, IMP38HC42, IMP38C43, IMP38HC43 ( ) Pins Are 14-Pin Devices Only Figure 3. UVL Protection Circuit ...

Page 8

Package Dimensions E1 E ...

Page 9

© 2000 IMP, Inc ...

Page 10

IMP, Inc. Corporate Headquarters ...

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