mic4043bm4 Micrel Semiconductor, mic4043bm4 Datasheet

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mic4043bm4

Manufacturer Part Number
mic4043bm4
Description
Mic4043 Low-voltage Secondary-side Shunt Regulator
Manufacturer
Micrel Semiconductor
Datasheet
General Description
The MIC4043 is a shunt regulator optimized for secondary-
side regulation in low-voltage power supplies. Featuring an
output stage guaranteed to swing within 400mV of ground,
the MIC4043 can be used in power supplies operating down
to 1.8V, even with optoisolators requiring greater than 1.2V of
headroom.
In power supply applications, the MIC4043 normally drives
the LED of an optically isolated feedback circuit. The MIC4043
monitors a resistively-divided output voltage and sinks error
current through the optoisolator’s LED (secondary side); the
optoisolator’s transistor (primary side) provides this signal to
the controller’s feedback input. The MIC4043 is also practical
for other voltage-monitoring applications requiring an open-
collector output.
The MIC4043 replaces conventional ’431-type shunt regula-
tors to allow low-voltage applications where there is inad-
equate headroom for a 2.5V regulator in series with an
optoisolator. Replacing ’431-type devices requires only a
minor change to the way that the resistive-divider values are
calculated.
Typical Application
November 2000
MIC4043
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
V
IN
1
2
3
4
MIC38HC43BN
COMP
FB
I
R
SNS
T
/C
T
GND
V
V
V
REF
OUT
DD
8
7
6
5
200kHz DC-DC Flyback Converter
Low-Side Feedback
ISOLATION
OPTICAL
MIC4043
Control
1
Features
• Ideal for 1.8V switching converters
• Low-voltage operation
• Easy to use
• 2% voltage tolerance over operating temperature range
Applications
• Optically isolated low-volage power supplies
• Low-voltage discrete regulator control
Low-Voltage Secondary-Side Shunt Regulator
400mV maximum saturation over
operating temperature range
voltage in, current out
1
2
4
3
7
6
MIC4043
IN
GND
SNK
V
Final Information
FB
OUT
COMPENSATION
MIC4043
1.245V
R2
R1
1
R1
R2
Return
V
OUT
MIC4043
Micrel

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mic4043bm4 Summary of contents

Page 1

MIC4043 General Description The MIC4043 is a shunt regulator optimized for secondary- side regulation in low-voltage power supplies. Featuring an output stage guaranteed to swing within 400mV of ground, the MIC4043 can be used in power supplies operating down to ...

Page 2

... MIC4043 Ordering Information Part Number Marking MIC4043BM4 RB1D Pin Configuration Pin Description Pin Number Pin Name SNK 3 GND 4 FB Absolute Maximum Ratings Input Voltage (V ) ...................................................... +15V IN Output Voltage (V ) ................................................ +15V SNK Storage Temperature (T ) ....................... – +150 C S ESD Rating, Note 3 human body model .................................................... 2kV machine model ...

Page 3

MIC4043 Electrical Characteristics bold values indicate – Parameter Condition Reference Voltage, Note 4 Reference Voltage Tolerance Supply Current I SNK Transconductance 1mA < SINK IN Output Transistor I SNK Saturation ...

Page 4

MIC4043 Transient Response 1a. 1.8V Output V IN Overshoot 25mV V OUT Transient Response 2a. 1.8V Output V IN Overshoot 56mV V OUT Transient Response 2a. 1.8V Output V IN Overshoot 64mV V OUT MIC4043 Turn On Transient Response 1b. ...

Page 5

MIC4043 Functional Diagram Functional Description The MIC4043 combines a G amplifier, precision 1.245V m reference, and a pass transistor in a single package. The operation of the MIC4043 is similar to conventional shunt regulators such as the industry standard ’431. ...

Page 6

MIC4043 Applications Information Replacement of ’431-Type Devices Since the MIC4043 uses a high-side reference, external voltage dividers providing the feedback voltage will be inverted when compared to those used with ’431-equiva- lent devices. The industry-standard ’431 is also typically used ...

Page 7

MIC4043 Off-Line 1.8V/2A Power Supply 85 to 264Vac 50/60Hz F1 Hot Ground 1A Neutral 20mH 2200pF C10 U2a 0.1 F 50/63V 2501 U1 MIC38HC43BN R5 1 COMP V REF 1.21k 1.21k ...

Page 8

MIC4043 Off-Line 2.5V/2A Power Supply 85 to 264Vac 50/60Hz F1 Hot Ground 1A Neutral 20mH 2200pF C10 U2a 0.1 F 50/63V 2501 U1 MIC38HC43BN R5 1 COMP V REF 1.21k 1.21k ...

Page 9

MIC4043 Off-Line 3.3V/2A Power Supply 85 to 264Vac 50/60Hz F1 Hot Ground 1A Neutral 20mH 2200pF C10 U2a 0.1 F 50/63V 2501 U1 MIC38HC43BN R5 1 COMP V REF 1.21k 1.21k ...

Page 10

MIC4043 Off-Line 5V/2A Power Supply 85 to 264Vac 50/60Hz F1 Hot Ground 1A Neutral 20mH 2200pF C10 U2a 0.1 F 50/63V 2501 U1 MIC38HC43BN R5 1 COMP V REF 1.21k 1.21k ...

Page 11

MIC4043 Package Information 0.950 (0.0374) TYP 3.05 (0.120) 2.67 (0.105) 0.800 (0.031) TYP 0.400 (0.016) TYP 3 PLACES November 2000 1.40 (0.055) 2.50 (0.098 1.20 (0.047) 2.10 (0.083 DIMENSIONS: 1.12 (0.044) 0.81 (0.032 0.10 ...

Page 12

MIC4043 MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 TEL This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of ...

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