MIC5237
Micrel
MIC5237
500mA Low-Dropout Regulator
Preliminary Information
General Description
The MIC5237 is a general-purpose low-dropout regulator
capable of 500mA output current with better than 3% output
voltage accuracy. Using Micrel’s proprietary Super
ßeta PNP™ process with a PNP pass element, these regu-
lators feature less than 300mV dropout voltage and typically
8mA ground current at full load.
Designed for applications that require moderate current over
a broad input voltage range, including hand-held and battery-
powered devices, the MIC5237 is intended for applications
that can tolerate moderate voltage drop at higher current.
Key features include low ground current to help prolong
battery life, reversed-battery protection, current limiting, over-
temperature shutdown, and thermally efficient packaging.
The MIC5237 is available in fixed output voltages only.
Features
• Guaranteed 500mA output over the full operating
temperature range
• Low 300mV typical dropout voltage at full load
• Extremely tight load and line regulation
• Current and thermal limiting
• Reversed-battery protection
• TO-220 and TO-263 packages
• Low temperature coefficient
• No-load stability
• Low-noise output
Applications
•
•
•
•
•
Portable and laptop computers
Desktop computer
Battery chargers
SMPS post-regulator/dc-to-dc modules
Consumer and personal electronics
For space-critical applications and improved performance,
see the MIC5209 and MIC5219. For output current require-
ments up to 750mA, see the MIC2937.
Ordering Information
Part Number
MIC5237-2.5BT
MIC5237-2.5BU
MIC5237-3.3BT
MIC5237-3.3BU
MIC5237-5.0BT
MIC5237-5.0BU
Voltage
2.5V
2.5V
3.3V
3.3V
5.0V
5.0V
Junct. Temp. Range
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
Package
TO-220
TO-263
TO-220
TO-263
TO-220
TO-263
Typical Application
V
IN
≥5.6V
MIC5237-5.0
IN
1.0µF
OUT
GND
1.0µF
tantalum
V
OUT
5.0V
±3%
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
January 2000
1
MIC5237
MIC5237
Micrel
Pin Configuration
3
TAB
OUT
GND
IN
2
1
MIC5237-x.xBT
(TO-220-3)
3
TAB
OUT
GND
IN
2
1
MIC5237-x.xBU
(TO-263-3)
Pin Description
Pin No.
1
2,
TAB
3
Pin Name
IN
GND
OUT
Pin Function
Supply Input
Ground: TO-220 and TO-263 pin 2 and
TAB
are internally connected.
Regulator Output
Absolute Maximum Ratings
Input Voltage (V
IN
) ........................................ –20V to +20V
Power Dissipation (P
D
) ............................ Internally Limited
Junction Temperature (T
J
) ....................... –40°C to +125°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
Operating Ratings
Input Voltage (V
IN
) ....................................... +2.5V to +16V
Junction Temperature (T
J
) ....................... –40°C to +125°C
Package Thermal Resistance
TO-220 (θ
JA
) ....................................................... 55°C/W
TO-220 (θ
JC
) ......................................................... 3°C/W
TO-263 (θ
JC
) ......................................................... 3°C/W
MIC5237
2
January 2000
MIC5237
Micrel
Electrical Characteristics
V
IN
= V
OUT
+ 1.0V; C
OUT
= 4.7µF, I
OUT
= 100µA; T
J
= 25°C,
bold
values indicate –40°C
≤
T
J
≤
+125°C; unless noted.
Symbol
V
OUT
∆V
OUT
/∆T
∆V
OUT
/V
OUT
∆V
OUT
/V
OUT
V
IN
– V
OUT
Parameter
Output Voltage Accuracy
Output Voltage
Temperature Coefficient
Line Regulation
Load Regulation
Dropout Voltage,
Note 4
Conditions
variation from nominal V
OUT
Note 2
V
IN
= V
OUT
+ 1V to 16V
0.015
I
OUT
= 100µA to 500mA,
Note 3
I
OUT
= 100µA
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 500mA
I
GND
Ground Pin Current,
Note 5
I
OUT
= 100µA
I
OUT
= 50mA
I
OUT
= 150mA
I
OUT
= 500mA
PSRR
I
LIMIT
∆V
OUT
/∆P
D
e
no
Note 1:
Min
–3
–5
Typical
Max
3
5
Units
%
%
ppm/°C
40
0.05
0.1
0.5
0.7
70
90
190
280
350
450
600
700
130
170
650
900
2.5
3.0
15
20
%/V
%/V
%
%
mV
mV
mV
mV
mV
mV
mV
mV
µA
µA
µA
µA
mA
mA
mA
mA
dB
0.05
10
115
165
300
80
350
1.8
8
75
700
0.05
500
Ripple Rejection
Current Limit
Thermal Regulation
Output Noise
f = 120Hz
V
OUT
= 0V
Note 6
V
OUT
= 5.0V, I
OUT
= 50mA,
C
OUT
= 2.2µF
900
1000
mA
%/W
nV/ Hz
Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when
operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction
temperature, T
J(max)
, the junction-to-ambient thermal resistance,
θ
JA
, and the ambient temperature, T
A
. The maximum allowable power
dissipation at any ambient temperature is calculated using: P
D(max)
= (T
J(max)
– T
A
)
÷ θ
JA
. Exceeding the maximum allowable power dissipa-
tion will result in excessive die temperature, and the regulator will go into thermal shutdown. See the “Thermal Considerations” section for
details.
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load
range from 100µA to 500mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V
differential.
Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of
the load current plus the ground pin current.
Thermal regulation is defined as the change in output voltage at a time “t” after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 500mA load pulse at V
IN
= 16V for t = 10ms.
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
January 2000
3
MIC5237
MIC5237
Micrel
Block Diagram
V
IN
IN
OUT
V
OUT
C
OUT
Bandgap
Ref.
Current Limit
Thermal Shutdown
MIC5237-x.x
GND
Fixed Regulator
MIC5237
4
January 2000
MIC5237
Micrel
Typical Characteristics
Power Supply
Rejection Ratio
0
-20
PSRR (dB)
-40
-60
-80
I
OUT
= 100µA
C
OUT
= 1µF
V
IN
= 6V
V
OUT
= 5V
PSRR (dB)
0
-20
-40
-60
-80
I
OUT
= 1mA
C
OUT
= 1µF
Power Supply
Rejection Ratio
V
IN
= 6V
V
OUT
= 5V
PSRR (dB)
0
-20
-40
-60
-80
Power Supply
Rejection Ratio
V
IN
= 6V
V
OUT
= 5V
I
OUT
= 100mA
C
OUT
= 1µF
-100
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
-100
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
-100
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
Power Supply Ripple Rejection
vs. Voltage Drop
60
RIPPLE REJECTION (dB)
50
40
30
20
10
0
0
C
OUT
= 1µF
0.1
0.2
0.3
VOLTAGE DROP (V)
0.4
NOISE (µV/√Hz)
1mA
10
1
0.1
0.01
0.001
Noise Performance
100mA
10mA
10mA
I
OUT
= 100mA
V
OUT
= 5V
C
OUT
= 10µF
electrolytic
1mA
0.0001
10 100 1k 10k 100k 1M 10M
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7
FREQUENCY (Hz)
January 2000
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MIC5237
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