MIC5237 DATA SHEET (11/05/2015) DOWNLOAD

MIC5237
500mA Low-Dropout Regulator
General Description
Features
The MIC5237 is a general-purpose low-dropout regulator
• Guaranteed 500mA output over the full operating
capable of 500mA output current with better than 3%
temperature range
output voltage accuracy. Using Micrel’s proprietary Super
•
Low 300mV typical dropout voltage at full load
ßeta PNP® process with a PNP pass element, these
• Extremely tight load and line regulation
regulators feature less than 300mV dropout voltage and
• Current and thermal limiting
typically 8mA ground current at full load.
• Reversed-battery protection
Designed for applications that require moderate current
• TO-220 and TO-263 packages
over a broad input voltage range, including hand-held and
battery-powered devices, the MIC5237 is intended for
• Low temperature coefficient
applications that can tolerate moderate voltage drop at
• No-load stability
higher current.
• Low-noise output
Key features include low ground current to help prolong
battery life, reversed-battery protection, current limiting,
over-temperature shutdown, and thermally efficient
Applications
packaging. The MIC5237 is available in fixed output
• Portable and laptop computers
voltages only.
• Desktop computer
For space-critical applications and improved performance,
• Battery chargers
see the MIC5209 and MIC5219. For output current
• SMPS post-regulator/dc-to-dc modules
requirements up to 750mA, see the MIC2937.
• Consumer and personal electronics
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
___________________________________________________________________________________________________________
Typical Application
Super βeta PNP is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
September 2007
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Micrel, Inc.
MIC5237
Ordering Information
Part Number
Voltage
Junction Temp. Range
Package
Standard
Pb-Free
MIC5237-2.5BU
MIC5237-2.5YU
2.5V
–40° to +125°C
TO-263-3
MIC5237-3.3BU
MIC5237-3.3YU
3.3V
–40° to +125°C
TO-263-3
MIC5237-5.0BT
MIC5237-5.0YT
5.0V
–40° to +125°C
TO-220-3
MIC5237-5.0BU
MIC5237-5.0YU
5.0V
–40° to +125°C
TO-263-3
Pin Configuration
TO-220-3 (T)
TO-263-3 (U)
Pin Description
Pin Number
Pin Name
Pin Function
1
IN
Supply Input.
2, TAB
GND
Ground: TO-220 and TO-263 pin 2 and TAB are internally connected.
3
OUT
Regulator Output.
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MIC5237
Absolute Maximum Ratings(1)
Operating Ratings
Supply Voltage (VIN) ..........................................–20 to +20V
Power Dissipation (PD). .............................Internally Limited
Lead Temperature (soldering, 5 sec.)........................ 260°C
Supply Voltage (VIN)...................................... +2.5V to +16V
Junction Temperature (TJ) ........................ –40°C to +125°C
Package Thermal Resistance
TO-220 (θJA).......................................................55°C/W
TO-220 (θJC) ........................................................3°C/W
TO-263 (θJC) ........................................................3°C/W
Electrical Characteristics
VIN = VOUT + 1.0V; COUT = 4.7µF; IOUT = 100µA; TJ = 25°C, bold values indicate –40°C< TJ < +125°C, unless noted.
Symbol
Parameter
Condition
VOUT
Output Voltage Accuracy
variation from nominal VOUT
∆VOUT/∆T
Output Voltage
Temperature Coefficient
Note 2
∆VOUT/VOUT
Line Regulation
VIN = VOUT + 1V to 16V
∆VOUT/VOUT
Load Regulation
IOUT = 100µA to 500mA, Note 3
VIN – VOUT
Dropout Voltage, Note 4
IGND
Ground Pin Current, Note 5
Min
Typ
–3
–5
Max
Units
3
5
%
%
ppm/°C
40
0.05
0.1
%/V
%/V
0.05
0.5
0.7
%
%
IOUT = 100µA
10
70
90
mV
mV
IOUT = 50mA
115
190
280
mV
mV
IOUT = 150mA
165
350
450
mV
mV
IOUT = 500mA
300
600
700
mV
mV
IOUT = 100µA
80
130
170
µA
µA
IOUT = 50mA
350
650
900
µA
µA
IOUT = 150mA
1.8
2.5
3.0
mA
mA
IOUT = 500mA
8
15
20
mA
mA
0.015
PSRR
Ripple Rejection
f = 120Hz
75
ILIMIT
Current Limit
VOUT = 0V
700
∆VOUT/∆PD
Thermal Regulation
Note 6
0.05
%/W
eno
Output Noise
VOUT = 5.0V, IOUT = 50Ma, COUT = 2.2µF
500
nV/√Hz
September 2007
3
dB
900
1000
mA
mA
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Micrel, Inc.
MIC5237
Notes:
1. 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, TJ(max), the
junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature
is calculated using: PD(max) = (T J(max) –TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the
regulator will go into thermal shutdown. See the “Thermal Considerations” section for details.
2. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
3. 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.
4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1Vdifferential.
5. 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.
6. 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 VIN = 16V for t = 10ms.
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MIC5237
Typical Characteristics
Power Supply
Rejection Ratio
-40
-60
-80
-100
1E+11E+21E+31E+41E+51E+61E+7
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
10
50
10mA
IOUT = 100mA
20
COUT = 1µF
10
0
0
IOUT = 1mA
COUT = 1µF
0.1
0.2
0.3
VOLTAGE DROP (V)
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0.4
-20
Power Supply
Rejection Ratio
VIN = 6V
VOUT = 5V
-40
-60
-80
IOUT = 100mA
COUT = 1µF
-100
1E+11E+21E+31E+41E+51E+61E+7
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
Noise Performance
1
1mA
NOISE (µV/ Hz)
RIPPLE REJECTION (dB)
60
30
-60
-100
1E+11E+21E+31E+41E+51E+61E+7
10 100 1k 10k 100k 1M 10M
FREQUENCY (Hz)
Power Supply Ripple Rejection
vs. Voltage Drop
40
-40
-80
IOUT = 100µA
COUT = 1µF
0
VIN = 6V
VOUT = 5V
-20
PSRR (dB)
-20
PSRR (dB)
0
VIN = 6V
VOUT = 5V
PSRR (dB)
0
Power Supply
Rejection Ratio
100mA
10mA
0.1
0.01
VOUT = 5V
1mA
0.001 C
= 10µF
OUT
electrolytic
0.0001
10 100 1E+31E+4
1k 10k 1E+51E+6
100k 1M 1E+7
10M
1E+11E+2
FREQUENCY (Hz)
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MIC5237
Block Diagram
Fixed Regulator
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MIC5237
read from the data sheet. Assuming the worst case
scenario is good design procedure, and the corresponding
ground current number can be obtained from the data
sheet. First, calculate the power dissipation of the device.
This example uses the MIC5237-5.0BT, a 13V input, and
500mA output current, which results in 20mA of ground
current, worst case. The power dissipation is the sum of
two power calculations: voltage drop × output current and
input voltage × ground current.
PD = [(VIN – VOUT) × IOUT] + (VIN × IGND)
PD = [(13V – 5V) × 500mA] + (13V × 20mA)
PD = 4.260W
From this number, the heat sink thermal resistance is
determined using the regulator’s maximum operating
junction temperature (TJ(max)) and the ambient temperature
(TA) along with the power dissipation number already
calculated.
TJ(MAX) = 125°C
θJC = junction-to-case thermal resistance
θCS = case-to-sink thermal resistance
θJA = junction-to-ambient thermal resistance
θSA = sink-to-ambient thermal resistance
To determine the heat sink thermal resistance, the junctionto-case thermal resistance of the device must be used
along with the case-to-heat sink thermal resistance. These
numbers show the heat-sink thermal resistance required at
TA =25°C that does not exceed the maximum operating
junction temperature.
Application Information
The MIC5237 is intended for general-purpose use and can
be implemented in a wide variety of applications where
500mA of output current is needed. It is available in several
voltage options for ease of use. For voltage options that are
not available on the MIC5237, consult the MIC5209 for a
500mA adjustable LDO regulator, or the MIC5219 for
applications that require only short-duration peak output
current.
Input Capacitor
A 1µF capacitor should be placed from IN to GND if there is
more than 10 inches of wire between the input and the ac
filter capacitor or if a battery is used as the input.
Output Capacitor
An output capacitor is required between OUT and GND to
prevent oscillation. 1µF minimum is recommended for
standard applications. Larger values improve the
regulator’s transient response. The output capacitor value
may be increased without limit.
The output capacitor should have an ESR (equivalent
series resistance) of about 5Ω or less and a resonant
frequency above 1MHz. Ultra low-ESR capacitors can
cause low-amplitude oscillations and/or under-damped
transient response. Most tantalum or aluminum electrolytic
capacitors are adequate; film types will work, but are more
expensive. Since many aluminum electrolytics have
electrolytes that freeze at about –30°C, solid tantalums are
recommended for operation below –25°C.
At lower values of output current, less output capacitance is
needed for output stability. The capacitor can be reduced to
0.47µF for current below 10mA or 0.33µF for currents
below 1mA.
For 2.5V applications a 22µF output capacitor is recommended to reduce startup voltage overshoot.
θ JA =
PD
θSA = θJA - θJC
θCS is approximately 1°C/W and θJC for the TO-220 is
3°C/W in this example.
No-Load Stability
The MIC5237 will remain stable and in regulation with no
load (other than the internal voltage divider) unlike many
other voltage regulators. This is especially important in
CMOSRAM keep-alive applications.
θ JA =
125 - 25
4.260W
θJA = 23.5°C/W
θSA = 23.5°C/W – (3°C/W + 1°C/W)
θSA = 19.5°C/W
Therefore, a heat sink with a thermal resistance of
19.5°C/W will allow the part to operate safely and it will not
exceed the maximum junction temperature of the device.
The heat sink can be reduced by limiting power dissipation,
by reducing the input voltage or output current. Either the
TO-220 or TO-263 package can operate reliably at 2W of
power dissipation without a heat sink. Above 2W, a heat
sink is recommended.
For a full discussion on voltage regulator thermal effects,
please refer to “Thermal Management” in Micrel’s
Designing with Low-Dropout Voltage Regulators handbook.
Thermal Considerations
Proper thermal design can be accomplished with some
basic design criteria and some simple equations. The
following information is required to implement a regulator
design.
VIN = input voltage
VOUT = output voltage
IOUT = output current
TA = ambient operating temperature
IGND = ground current
The regulator ground current, IGND, can be measured or
September 2007
TJ(max) - TA
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MIC5237
Package Information
3-Pin TO-220 (T)
3-Pin TO-263 (U)
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MIC5237
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2000 Micrel, Incorporated.
September 2007
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