38HC43 Datasheet PDF - Micrel Semiconductor
| Part Number | 38HC43 | |
| Description | MIC38HC43 | |
| Manufacturers | Micrel Semiconductor | |
| Logo |  |
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MIC38HC42/3/4/5
Micrel, Inc.
MIC38HC42/3/4/5
BiCMOS 1A Current-Mode PWM Controllers
General Description
The MIC38HC4x family are fixed frequency current-mode
PWM controllers with 1A drive current capability. Micrel’s
BiCMOS devices are pin-compatible with 384x bipolar de-
vices. Their high output drive, with fast rise and fall times,
combined with low startup current make it an ideal PWM
controller where high efficiency is required.
Undervoltage lockout circuitry allows the ’42 and ’44 versions
to start up at 14.5V and operate down to 9V, and the ’43 and
’45 versions start at 8.4V with operation down to 7.6V. All
versions operate up to 20V.
When compared to bipolar UC384x devices operating from a
15V supply, start-up current has been reduced to 50µA
typical and operating current has been reduced to 4.0 mA
typical. Decreased output rise and fall times drive larger
MOSFETs, and rail-to-rail output capability increases effi-
ciency, especially at lower supply voltages. The MIC38HC4x
also features a trimmed oscillator discharge current and
bandgap reference.
MIC38HC4x-1 is available in 14-pin plastic DIP and SOIC
packages. 8-pin devices feature small size, while 14-pin
devices separate the analog and power connections for
improved performance and power dissipation.
Features
• Fast 20ns output rise and 15ns output fall times
• –40°C to +85°C temperature range
exceeds UC284x specifications
• High-performance, low-power BiCMOS Process
• Ultralow start-up current (50µA typical)
• Low operating current (4mA typical)
• High output drive (1A peak current, HC version)
• CMOS outputs with rail-to-rail swing
• Current-mode operation up to 500kHz
• Trimmed 5V bandgap reference
• Pin-for-pin compatible with UC3842/3843/3844/3845(A)
• Trimmed oscillator discharge current
• UVLO with hysteresis
• Low cross-conduction currents
Applications
• Current-mode, off-line, switched-mode power supplies
• Current-mode, dc-to-dc converters.
• Step-down “buck” regulators
• Step-up “boost” regulators
• Flyback, isolated regulators
• Forward converters
• Synchronous FET converters
Functional Diagram
VDD
7 (12)
VREF
8 (14)
RT/CT
4 (7)
FB
2 (3)
2.5V
35V
5V
Reference
Oscillator
2R
R
UVLO
*
†
TQ
‡
S
R
Q
(VD)
(11)
OUT
6 (10)
(PGND)
(8)
*
COMP GND*(AGND) ISNS
1 (1)
5 (9)
3 (5)
( ) pins are on MIC38HC4x-1 (14-lead) versions only
* MIC38HC4x (8-lead) versions only
† MIC38HC42, MIC38HC43 (96% max. duty cycle) versions only
‡ MIC38HC44, MIC38HC45 (50% max. duty cycle) versions only
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 2005
1
M9999-042205
Datasheet pdf - http://www.DataSheet4U.net/
|
| |
 
www.DataSheet.co.kr
MIC38HC42/3/4/5
Micrel, Inc.
Parameter
Test Conditions
Min Typ Max Units
Current Sense
Gain
Notes 2, 3
2.85 3.0 3.15 V/V
MaximumThreshold
PSRR
Input Bias Current
VCOMP = 5V, Note 2
12 ≤ VDD ≤ 18V, Note 2
0.9 1 1.1
70
–0.1 –2
V
dB
µA
Delay to Output
120 250
ns
Output
RDS(ON) ‘HC’ High
RDS(ON) ‘HC’ Low
Rise Time
Fall Time
Undervoltage Lockout
ISOURCE = 200mA
ISINK = 200mA
TA = 25°C, CL = 1nF
TA = 25°C, CL = 1nF
10 Ω
5.5 Ω
20 50 ns
15 40 ns
Start Threshold
MIC38HC42/4
13.5 14.5 15.5
V
MIC38HC43/5
7.8 8.4 9.0
V
Minimum Operating Voltage
MIC38HC42/4
8 9 10 V
MIC38HC43/5
7.0 7.6 8.2
V
Pulse Width Modulator
Maximum Duty Cycle
MIC38HC42/3
94 96
%
MIC38HC44/5
46 50
%
Minimum Duty Cycle
0%
Total Standby Current
Start-Up Current
VDD = 13V, 38HC42/44
VDD = 7.5V, 38HC43/45
50 200 µA
Operating Supply Current
VFB = VISNS = 0V
4.0 6.0 mA
Zener Voltage (VDD)
IDD = 25mA, Note 6
Note 1: These parameters, although guaranteed, are not 100% tested in production.
Note 2: Parameter measured at trip point of latch with VEA = 0.
Note 3: Gain defined as:
30 37
V
A=
∆ VPIN1 ;
VTH (ISNS )
0
≤
VTH (ISNS )
≤
0.8V
Note 4: Adjust VDD above the start threshold before setting at 15V.
Note 5: Output frequency equals oscillator frequency for the MIC38HC42 and MIC38HC43. Output frequency for the MIC38HC44, and
MIC38HC45 equals one half the oscillator frequency.
Note 6: On 8-pin version, 20V is maximum input on pin 7, as this is also the supply pin for the output stage. On 14-pin version, 40V is
maximum for pin 12 and 20V maximum for pin 11.
April 2005
5
M9999-042205
Datasheet pdf - http://www.DataSheet4U.net/
Preview 5 Page |
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| Information | Total 8 Pages | |
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| Download | [ 38HC43.PDF Datasheet ] | |
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