MIC4043YM4 [MIC]
Low-Voltage Secondary-Side Shunt Regulator Final Information; 低电压二次侧并联稳压器最终信息
| 型号： | MIC4043YM4 |
| 厂家： | 
MIC GROUP RECTIFIERS |
| 描述： | Low-Voltage Secondary-Side Shunt Regulator Final Information |
| 文件： | 总12页 (文件大小：448K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4043
Low-Voltage Secondary-Side Shunt Regulator
Final Information
General Description
Features
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
to1.8V, evenwithoptoisolatorsrequiringgreaterthan1.2Vof
headroom.
• Ideal for 1.8V switching converters
• Low-voltage operation
400mV maximum saturation over
operating temperature range
• Easy to use
voltage in, current out
• 2% voltage tolerance over operating temperature range
In power supply applications, the MIC4043 normally drives
theLEDofanopticallyisolatedfeedbackcircuit.TheMIC4043
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
thecontroller’sfeedbackinput. TheMIC4043isalsopractical
for other voltage-monitoring applications requiring an open-
collector output.
Applications
• Optically isolated low-volage power supplies
• Low-voltage discrete regulator control
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
OPTICAL
ISOLATION
MIC4043
IN SNK
GND FB
MIC4043
Low-Side Feedback
VIN
COMPENSATION
Control
VOUT
1
2
7
6
R1
R2
MIC38HC43BN
Return
1
2
3
4
8
7
6
5
COMP
FB
VREF
VDD
4
3
ISNS
VOUT
GND
R2
R1
V
= 1.245V
+1
OUT
RT/CT
200kHz DC-DC Flyback Converter
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
November 2000
1
MIC4043
MIC4043
Micrel
Ordering Information
Part Number
Marking Voltage Tolerance Configuration
Temperature Range
Package
Lead-Finish
MIC4043BM4
MIC4043YM4
RB1D
RB1D
1.245V
1.245V
1%
1%
Open Collector
Open Collector
–40°C to +85°C
–40°C to +85°C
SOT-143
SOT-143
Leaded
Pb-Free
Pin Configuration
FB
4
GND
Part
Identification
3
RBxx
1
2
IN
SNK
MIC4043
Pin Description
Pin Number
Pin Name
IN
Pin Function
1
2
3
4
Input: Supply voltage input.
Sink (Output): NPN open collector output.
Ground
SNK
GND
FB
Feedback (Input): Feedback input from external voltage-divider network.
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Input Voltage (V ) ......................................................+15V
Input Voltage (V ) ......................................................+10V
IN
IN
Output Voltage (V
) ................................................+15V
Output Voltage (V
) ................................................+10V
SNK
SNK
Storage Temperature (T ) ....................... –65°C to +150°C
Maximum Output Current (I
) ................................ 15mA
S
SNK
ESD Rating, Note 3
Temperature Range (T ) ........................... –40°C to +85°C
A
human body model.................................................... 2kV
machine model ........................................................200V
MIC4043
2
November 2000
MIC4043
Micrel
Electrical Characteristics
TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted
Parameter
Condition
Min
Typ
Max
Units
Reference Voltage, Note 4
Reference Voltage Tolerance
1.245
V
±1
±2
%
%
Supply Current
ISNK = 0mA
35
65
70
µA
µA
Transconductance
∆ISINK/∆VIN
1mA < ISNK < 15mA
ISNK = 15mA
3.5
2
150
160
S
S
Output Transistor
Saturation Voltage
250
400
mV
mV
Output Leakage
VSNK = 5V, output transistor off
0.5
1
µA
µA
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Machine model, 200pF.
Note 4. Reference voltage is not referenced to ground. The reference is between pins IN and FB.
Test Circuits
Floating
Bench
Supply
R1
MIC4043
1k
Analyzer
R
OUT
IN SNK
RETURN
GND FB
C1*
R
A
R2
33k
R
Do Not Ground!
R
A
R3
50Ω
OUTPUT
* Compensation element
A
VOUT
1.8V
2.5V
3.3V
R1
72k
33k
20k
R2
33k
33k
33k
R3
20k
40k
C1
0.001µF
0.001µF
0.001µF
A
0k
15
Test Circuit 1. Compensation (Bode Plot) Circuit
Supply
OUT
RETURN
R1
MIC4043
1k
IN SNK
GND FB
C1
R2
33k
R3
* Compensation components
Test Circuit 2. Transient Response Circuit
November 2000
3
MIC4043
MIC4043
Micrel
Transient Response 1a.
1.8V Output
Turn On Transient Response 1b.
1.8V Output
6.0V
5.0V
VIN
VIN
AC
Coupled
Overshoot 25mV
VREG
1.8V
VREG
1.8V
VOUT
VOUT
AC
Coupled
Transient Response 2a.
1.8V Output
Turn On Transient Response 2b.
1.8V Output
6.0V
5.0V
VIN
VIN
AC
Coupled
Overshoot 56mV
VREG
2.5V
VREG
2.5V
VOUT
VOUT
AC
Coupled
Transient Response 2a.
1.8V Output
Turn On Transient Response 3b.
1.8V Output
6.0V
5.0V
VIN
VIN
AC
Coupled
VREG
3.3V
VOUT
VREG
3.3V
VOUT
AC
Coupled
MIC4043
4
November 2000
MIC4043
Micrel
Functional Diagram
IN
VREF
1.245V
SNK
FB
MIC4043
GND
Reference
Functional Description
The MIC4043 uses a high-side reference. External voltage
dividers providing feedback to the MIC4043 will be inverted
when compared to those used with ’431-equivalent devices.
The MIC4043 combines a G amplifier, precision 1.245V
reference, and a pass transistor in a single package.
m
TheoperationoftheMIC4043issimilartoconventionalshunt
regulators such as the industry standard ’431. In a closed
loop system, the MIC4043 maintains the desired feedback
voltage at the FB pin by sinking current onto the SNK pin
proportionaltotheerrorvoltageattheFBpin. Theratioofsink
currenttoerrorvoltageisthetransconductanceofthedevice.
Behavior
The external feedback voltage is compared to the internal
high-side 1.245V reference.
If the feedback voltage, V , is less than V – V , the
REF
FB
IN
amplifier provides no drive to the sink transistor. If the
feedback voltages is greater than V – V , the amplifier
IN
REF
drives the pass transistor which sinks current to ground.
November 2000
5
MIC4043
MIC4043
Micrel
response, ifanetworkanalyzerisnotavailable, istostepload
the output of the systems from 10% to 100% of nominal load.
The resultant small signal response at the output of the
systemswillprovideanideaofwhichdirectiontogobasedon
Applications Information
Replacement of ’431-Type Devices
Since the MIC4043 uses a high-side reference, external
voltage dividers providing the feedback voltage will be
invertedwhencomparedtothoseusedwith’431-equiva-
lent devices.
the overshoot and settling time of V
.
OUT
Voltage Detector
Theindustry-standard’431isalsotypicallyusedinserieswith
anopto-isolatorLED. Thisconfigurationhasavoltagedropof
at least 2.5V for the ’431 plus 1.4V for the LED (3.9V). More
recent lower-voltage shunt regulators require at least 1.25V
of headroom in addition to the 1.4V for the opto isolator, for
a total of 2.65V.
R2
R1
VTRIP = 1.245V
+1
VOUT
(FROM
R1 RPULL-UP
Logic
POWER
SUPPLY)
MIC4043
IN SNK
Output
GND FB
DISABLED
ENABLED
R2
The MIC4043 removes the need to place the shunt reference
in parallel with the opto-isolator. The MIC4043 combines a
1.245V reference in conjunction with an error amplifier that
drives an NPN output transistor. The NPN transistor is
connected in series with the opto-isolator and regulates the
drive current in the opto-isolator. Unlike conventional shunt
regulators, the MIC4043 does not have to connect the shunt
reference in series with the opto-isolator. Only the NPN
output stage is in series with the opto-isolator, so the voltage
drop is just the saturation voltage or one transistor, typucally
160mV at full load
33k
Figure 1. Voltage Detector
Figure 1 shows a simple voltage threshold detector with a
logic output.
High-Current Regulator
VIN
VOUT = 2.5V
IBIAS
≥500µA
RBIAS
R2
R1
Q1
V
= 1.245V
+1
OUT
R1= 33k, R2 = 33k
MIC4043
Compensation
IN SNK
Thenoninvertingsideoftheerroramplifierisconnectedtothe
high-side reference; the reference is connected to the IN pin.
The inverting side of the error amplifier is brought out to the
FB pin. For some applications, no compensation is needed,
but for most, some resistor capacitor network is necessary
between the FB pin and GND pin. The value of the feedback
capacitance is application specific, but for most applications
100pFto3000pFisallthatisneeded. Changingthefeedback
capacitor changes the loop response; that is, phase and gain
margin. An empirical way to check overall system loop
GND FB
R2
33k
1000pF
40Ω
Figure 2. High-Current Regulator
For the high-current regulator shown in Figure 2, headroom
is equal to the saturation voltage of Q1 plus the saturation
voltage of the MIC4043 (V
= 200mV).
SAT(min)
MIC4043
6
November 2000
MIC4043
Micrel
Off-Line 1.8V/2A Power Supply
U2b
2501
R10
72k
1%
85 to 264Vac
50/60Hz
BR1
F1
1A
Hot
U3
MIC4043
DBR1
L1
Ground
Neutral
C1
0.1µF
250V
IN SNK
GND FB
C4
20mH
47µF
400V
R11
33k
1%
C2
C3
2200pF
400V
1000pF
2200pF
400V
249Ω
D4
12CTQ045
V
OUT
+1.8V/2A
L2
5µH
1
7
R2
R14
332k
1%
C10
0.1µF
80T
3T
200Ω
U2a
2501
C11
C12
1%
50/63V
1200µF
220µF
10V
2
R3
332k
1%
6
Return
10V
R4
34Ω
1%
U1
D1
MIC38HC43BN
1N4448
R5
1
2
3
4
8
7
6
5
COMP
FB
VREF
VDD
T1
4
1.21k 1%
D2
18V
C8
22µF
25V
10T
C5
R6
0.1µF
50/
1.21k
1%
3
R2
ISNS
VOUT
GND
VTRIP = 1.245V
+1
63V
R1
RT/CT
R13
10Ω 1%
Q1
IRFIBE30G
C9
R7
100pF
14k 1%
1kV
R1
1k 1%
C6
470pF
63V
C7
470pF
63V
R8
1.9Ω
1/4W
1%
R9
D3
UF4005
470Ω
1/2W
Figure 3. Off-Line 1.8V/2A Power Supply
Figure 3b. 1.8V/2A Bode Plot
Figure 3a. 1.8V/1A Bode Plot
(θ margin = 87°)
(θ margin = 102°)
November 2000
7
MIC4043
MIC4043
Micrel
Off-Line 2.5V/2A Power Supply
U2b
2501
R10
72k
1%
85 to 264Vac
50/60Hz
BR1
F1
1A
Hot
U3
MIC4043
DBR1
L1
Ground
Neutral
C1
0.1µF
250V
IN SNK
GND FB
C4
20mH
47µF
400V
R11
33k
1%
C2
C3
2200pF
400V
1000pF
2200pF
400V
249Ω
D4
12CTQ045
V
OUT
+2.5V/2A
L2
5µH
1
7
R2
R14
332k
1%
C10
0.1µF
80T
3T
200Ω
U2a
2501
C11
C12
1%
50/63V
1200µF
220µF
10V
2
R3
332k
1%
6
Return
10V
R4
34Ω
1%
U1
D1
MIC38HC43BN
1N4448
R5
1
2
3
4
8
7
6
5
COMP
FB
VREF
VDD
T1
4
1.21k 1%
D2
18V
C8
22µF
25V
10T
C5
R6
0.1µF
50/
1.21k
1%
3
R2
ISNS
VOUT
GND
VTRIP = 1.245V
+1
63V
R1
RT/CT
R13
10Ω 1%
Q1
IRFIBE30G
C9
R7
100pF
14k 1%
1kV
R1
1k 1%
C6
470pF
63V
C7
470pF
63V
R8
1.9Ω
1/4W
1%
R9
D3
UF4005
470Ω
1/2W
Figure 4. Off-Line 2.5V/2A Power Supply
Figure 4a. 2.5V/1A Bode Plot
Figure 4b. 2.5V/2A Bode Plot
(θ margin = 83°)
(θ margin = 83°)
MIC4043
8
November 2000
MIC4043
Micrel
Off-Line 3.3V/2A Power Supply
U2b
2501
R10
72k
1%
85 to 264Vac
50/60Hz
BR1
F1
1A
Hot
U3
MIC4043
DBR1
L1
Ground
Neutral
C1
0.1µF
250V
IN SNK
GND FB
C4
20mH
47µF
400V
R11
33k
1%
C2
C3
2200pF
400V
1000pF
2200pF
400V
249Ω
D4
12CTQ045
V
OUT
+3.3V/2A
L2
5µH
1
7
R2
R14
332k
1%
C10
0.1µF
80T
3T
200Ω
U2a
2501
C11
C12
1%
50/63V
1200µF
220µF
10V
2
R3
332k
1%
6
Return
10V
R4
34Ω
1%
U1
D1
MIC38HC43BN
1N4448
R5
1
2
3
4
8
7
6
5
COMP
FB
VREF
VDD
T1
4
1.21k 1%
D2
18V
C8
22µF
25V
10T
C5
R6
0.1µF
50/
1.21k
1%
3
R2
ISNS
VOUT
GND
VTRIP = 1.245V
+1
63V
R1
RT/CT
R13
10Ω 1%
Q1
IRFIBE30G
C9
R7
100pF
14k 1%
1kV
R1
1k 1%
C6
470pF
63V
C7
470pF
63V
R8
1.9Ω
1/4W
1%
R9
D3
UF4005
470Ω
1/2W
Figure 5. Off-Line 3.3V/2A Power Supply
Figure 5b. 3.3V/2A Bode Plot
Figure 5a. 3.3V/1A Bode Plot
(θ margin = 80°)
(θ margin = 82°)
November 2000
9
MIC4043
MIC4043
Micrel
Off-Line 5V/2A Power Supply
U2b
2501
R10
72k
1%
85 to 264Vac
50/60Hz
BR1
F1
1A
Hot
U3
MIC4043
DBR1
L1
Ground
Neutral
C1
0.1µF
250V
IN SNK
GND FB
C4
20mH
47µF
400V
R11
33k
1%
C2
C3
2200pF
400V
1000pF
2200pF
400V
249Ω
D4
12CTQ045
V
OUT
+5.0V/2A
L2
5µH
1
7
R2
R14
332k
1%
C10
0.1µF
80T
3T
200Ω
U2a
2501
C11
C12
1%
50/63V
1200µF
220µF
10V
2
R3
332k
1%
6
Return
10V
R4
34Ω
1%
U1
D1
MIC38HC43BN
1N4448
R5
1
2
3
4
8
7
6
5
COMP
FB
VREF
VDD
T1
4
1.21k 1%
D2
18V
C8
22µF
25V
10T
C5
R6
0.1µF
50/
1.21k
1%
3
R2
ISNS
VOUT
GND
VTRIP = 1.245V
+1
63V
R1
RT/CT
R13
10Ω 1%
Q1
IRFIBE30G
C9
R7
100pF
14k 1%
1kV
R1
1k 1%
C6
470pF
63V
C7
470pF
63V
R8
1.9Ω
1/4W
1%
R9
D3
UF4005
470Ω
1/2W
Figure 6. Off-Line 5V/2A Power Supply
Figure 6b. 5V/2A Output Bode Plot
Figure 6a. 5V/1A Output Bode Plot
(θ margin = 61°)
(θ margin = 67°)
MIC4043
10
November 2000
MIC4043
Micrel
Package Information
0.950 (0.0374) TYP
1.40 (0.055) 2.50 (0.098)
1.20 (0.047) 2.10 (0.083)
C
L
C
L
DIMENSIONS:
MM (INCH)
1.12 (0.044)
0.81 (0.032)
3.05 (0.120)
2.67 (0.105)
0.150 (0.0059)
0.089 (0.0035)
8°
0°
0.10 (0.004)
0.013 (0.0005)
0.800 (0.031) TYP
0.41 (0.016)
0.13 (0.005)
0.400 (0.016) TYP 3 PLACES
SOT-143 (M4)
November 2000
11
MIC4043
MIC4043
Micrel
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 2000 Micrel Incorporated
MIC4043
12
November 2000
相关型号：
MIC4043YM4TR
1-OUTPUT THREE TERM VOLTAGE REFERENCE, 1.245V, PDSO4, LEAD FREE, SOT-143, 4 PIN
MICROCHIP
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