MIC5209_04 [MICREL]
500mA Low-Noise LDO Regulator; 500毫安低噪声LDO稳压器
| 型号： | MIC5209_04 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 500mA Low-Noise LDO Regulator |
| 文件： | 总13页 (文件大小：1483K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
500mA Low-Noise LDO Regulator
General Description
The MIC5209 is an efficient linear voltage regulator with very
low dropout voltage, typically 10mV at light loads and less
than 500mV at full load, with better than 1% output voltage
accuracy.
• Meets Intel® Slot 1 and Slot 2 requirements
• Guaranteed 500mA output over the full operating
temperature range
• Low 500mV maximum dropout voltage at full load
• Extremely tight load and line regulation
• Thermally-efficient surface-mount package
• Low temperature coefficient
• Current and thermal limiting
• Reversed-battery protection
• No-load stability
• 1% output accuracy
• Ultra-low-noise capability in SO-8 and TO-263-5
• Ultra-small 3mm x 3mm MLF™ package
Designedespeciallyforhand-held,battery-powereddevices,
the MIC5209 features low ground current to help prolong
battery life. An enable/shutdown pin on SO-8 and TO-263-
5 versions can further improve battery life with near-zero
shutdown current.
Key features include reversed-battery protection, current
limiting,overtemperatureshutdown,ultra-low-noisecapability
(SO-8 and TO-263-5 versions), and availability in thermally
efficient packaging. The MIC5209 is available in adjustable
or fixed output voltages.
Applications
• Pentium II Slot 1 and Slot 2 support circuits
• Laptop, notebook, and palmtop computers
• Cellular telephones
For space-critical applications where peak currents do not
exceed 500mA, see the MIC5219.
• Consumer and personal electronics
• SMPS post-regulator/dc-to-dc modules
• High-efficiency linear power supplies
Typical Applications
MIC5209-2.5BS
1
2
3
VIN
VOUT
≥ 3.0V
2.5V ±1%
0.1µF
22µF
tantalum
3.3V Nominal-Input Slot-1
Power Supply
MIC5209-5.0BM
ENABLE
SHUTDOWN
1
2
3
4
8
7
6
5
VIN
6V
VOUT
5V
2.2µF
tantalum
470pF
(OPTIONAL)
Ultra-Low-Noise 5V Regulator
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
June 2006
1
M9999-060906
MIC5209
Micrel, Inc.
Ordering Information
Part Number
MIC5209-2.5BS
MIC5209-2.5YS
MIC5209-3.0BS
MIC5209-3.0YS
MIC5209-3.3BS
MIC5209-3.3YS
MIC5209-3.6BS
MIC5209-3.6YS
MIC5209-4.2BS
MIC5209-4.2YS
MIC5209-5.0BS
MIC5209-5.0YS
MIC5209-1.8BM*
MIC5209-1.8YM*
MIC5209-2.5BM
MIC5209-2.5YM
MIC5209-3.0BM
MIC5209-3.0YM
MIC5209-3.3BM
MIC5209-3.3YM
MIC5209-3.6BM
MIC5209-3.6YM
MIC5209-5.0BM
MIC5209-5.0YM
MIC5209BM
Voltage
Junction 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
-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
-0°C to +125°C
-0°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
-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
-40°C to +125°C
-0°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
-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
-40°C to +125°C
-40°C to +125°C
Package
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOT-223
SOIC-8
Pb-Free
2.5V
2.5V
3.0V
3.0V
3.3V
3.3V
3.6V
3.6V
4.2V
4.2V
5.0V
5.0V
1.8V
1.8V
2.5V
2.5V
3.0V
3.0V
3.3V
3.3V
3.6V
3.6V
5.0V
5.0V
Adj.
X
X
X
X
X
X
X
X
X
X
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
MIC5209YM
Adj.
SOIC-8
X
X
MIC5209-1.8YU*
MIC5209-2.5BU
MIC5209-2.5YU
MIC5209-3.0BU
MIC5209-3.0YU
MIC5209-3.3BU
MIC5209-3.3YU
MIC5209-3.6BU
MIC5209-3.6YU
MIC5209-5.0BU
MIC5209-5.0YU
MIC5209BU
1.8V
2.5V
2.5V
3.0V
3.0V
3.3V
3.3V
3.6V
3.6V
5.0V
5.0V
Adj.
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
TO-263-5
8-pin MLF™
X
X
X
X
MIC5209YU
Adj.
X
X
MIC5209YML
Adj.
* Contact marketing for availability.
M9999-060906
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June 2006
MIC5209
Micrel, Inc.
Pin Configuration
GND
TAB
Part
Identification
VIN
VIN
1
2
3
4
8
7
6
5
EN
Y
5209
YWW
GND
ADJ
NC
VOUT
VOUT
1
2
3
IN GND OUT
MIC5209-x.xBS
SOT-223
Fixed Voltages
MIC5209YML
8-Pin 3x3 MLF
Adjustable Voltages
5 BYP
4 OUT
3 GND
2 IN
EN
IN
GND
GND
GND
GND
1
2
3
4
8
7
6
5
OUT
BYP
1 EN
MIC5209-x.xBU
TO-263-5
Fixed Voltages
MIC5209-x.xBM
SO-8
Fixed Voltages
5 ADJ
4 OUT
3 GND
2 IN
EN
IN
GND
GND
GND
GND
1
2
3
4
8
7
6
5
OUT
ADJ
1 EN
MIC5209BU
TO-263-5
Adjustable Voltage
MIC5209BM
SO-8
Adjustable Voltage
Pin Description
Pin No.
8-pin MLF SOT-223
Pin No.
Pin No.
SO-8
Pin No.
TO-263-5
Pin Name Pin Function
1, 2
7
1
2
2
3
IN
Supply Input.
2, TAB
5–8
GND
Ground: SOT-223 pin 2 and TAB are internally connected. SO-8
pins 5 through 8 are internally connected.
3, 4
8
3
3
1
4
1
OUT
EN
Regulator Output. Pins 3 and 4 must be tied together.
Enable (Input): CMOS compatible control input. Logic high =
enable; logic low = shutdown.
4 (fixed)
4 (adj.)
5 (fixed)
5 (adj.)
BYP
ADJ
Reference Bypass: Connect external 470pF capacitor to GND to
reduce output noise. May be left open. For 1.8V or 2.5V operation,
see “Applications Information.”
6
Adjust (Input): Feedback input. Connect to resistive voltage-divider
network.
June 2006
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Micrel, Inc.
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Input Voltage (V )
–20V to +20V
Supply Input Voltage (V )
+2.5V to +16V
IN
IN
(3)
Power Dissipation (P )
Internally Limited
Enable Input Voltage (V
)
0V to V
D
EN
IN
Junction Temperature (T )
Junction Temperature (T )
J
J
all except 1.8V
1.8V only
–40°C to +125°C
0°C to +125°C
all except 1.8V
1.8V only
–40°C to +125°C
0°C to +125°C
Lead Temperature (soldering, 5 sec.)
260°C
Package Thermal Resistance
Note 3
Storage Temperature (T )
–65°C to +150°C
S
(Note 11)
VIN = VOUT + 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C except 0°C ≤ TJ ≤ +125°C
for 1.8V version; unless noted.
Symbol
Parameter
Conditions
Min Typical Max
Units
VOUT
Output Voltage Accuracy
variation from nominal VOUT
–1
–2
1
2
%
%
ΔVOUT/ΔT
Output Voltage
Temperature Coefficient
Note 4
40
0.009
0.05
10
ppm/°C
ΔVOUT/VOUT Line Regulation
VIN = VOUT + 1V to 16V
IOUT = 100µA to 500mA(5)
IOUT = 100µA
0.05
0.1
%/V
%/V
ΔVOUT/VOUT Load Regulation
0.5
0.7
%
%
VIN – VOUT
Dropout Voltage(6)
60
80
mV
mV
IOUT = 50mA
115
165
350
80
175
250
mV
mV
IOUT = 150mA
300
400
mV
mV
IOUT = 500mA
500
600
mV
mV
IGND
Ground Pin Current(7, 8)
VEN ≥ 3.0V, IOUT = 100µA
VEN ≥ 3.0V, IOUT = 50mA
VEN ≥ 3.0V, IOUT = 150mA
VEN ≥ 3.0V, IOUT = 500mA
130
170
µA
µA
350
1.8
650
900
µA
µA
2.5
3.0
mA
mA
8
20
25
mA
mA
IGND
Ground Pin Quiescent Current(8)
VEN ≤ 0.4V (shutdown)
VEN ≤ 0.18V (shutdown)
f = 120Hz
0.05
0.10
75
3
8
µA
µA
dB
PSRR
ILIMIT
Ripple Rejection
Current Limit
VOUT = 0V
700
900
1000
mA
mA
ΔVOUT/ΔPD
eno
Thermal Regulation
Output Noise(10)
Note 9
0.05
500
%/W
VOUT = 2.5V, IOUT = 50mA,
COUT = 2.2µF, CBYP = 0
nV √Hz
IOUT = 50mA, COUT = 2.2µF, CBYP = 470pF
300
nV √Hz
M9999-060906
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June 2006
MIC5209
Micrel, Inc.
ENABLE Input
V
Enable Input Logic-Low Voltage
VEN = logic low (regulator shutdown)
0.4
0.18
V
V
VEN = logic high (regulator enabled)
V≤ 0.4V
2.0
V
I
IENH
Enable Input Current
0.01
0.01
5
–1
µA
µA
V≤ 0.18V
–2
VENH = 2.0V
20
25
µA
µA
VENH = 16V
30
50
µA
µA
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. The maximum allowable power dissipation at any TA (ambient temperature) is calculated using: PD(max) = (TJ(max) – TA)
θJA. Exceeding the
maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. See Table 1 and the
“Thermal Considerations” section for details.
4. Output voltage temperature coefficient is the worst case voltage change divided by the total temperature range.
5. 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.
6. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differen-
tial.
7. 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.
8. VEN is the voltage externally applied to devices with the EN (enable) input pin. [SO-8 (M) and TO-263-5 (U) packages only.]
9. Thermal regulation is the change in output voltage at a time “t” after a change in power dissipation is applied, excluding load or line regulation ef-
fects. Specifications are for a 500mA load pulse at VIN = 16V for t = 10ms.
10. CBYP is an optional, external bypass capacitor connected to devices with a BYP (bypass) or ADJ (adjust) pin. [SO-8 (M) and TO-263-5 (U) packages
only].
June 2006
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M9999-060906
MIC5209
Micrel, Inc.
Block Diagrams
OUT
IN
VOUT
COUT
VIN
Bandgap
Ref.
Current Limit
Thermal Shutdown
MIC5209-x.xBS
GND
Low-Noise Fixed Regulator (SOT-223 version only)
OUT
IN
VOUT
COUT
VIN
BYP
CBYP
(optional)
Bandgap
Ref.
EN
Current Limit
Thermal Shutdown
MIC5209-x.xBM/U
GND
Ultra-Low-Noise Fixed Regulator
OUT
IN
VOUT
COUT
VIN
R1
R2
ADJ
CBYP
(optional)
Bandgap
Ref.
EN
Current Limit
Thermal Shutdown
MIC5209BM/U [adj.]
GND
Ultra-Low-Noise Adjustable Regulator
M9999-060906
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June 2006
MIC5209
Micrel, Inc.
Typical Characteristics
Power Supply
Power Supply
Power Supply
Rejection Ratio
Rejection Ratio
Rejection Ratio
0
0
-20
0
-20
VIN = 6V
VOUT = 5V
VIN = 6V
VOUT = 5V
VIN = 6V
OUT = 5V
V
-20
-40
-60
-40
-40
-60
-60
IOUT = 100mA
COUT = 1µF
-80
-80
-80
IOUT = 100µA
COUT = 1µF
IOUT = 1mA
COUT = 1µF
-100
-100
-100
1k 10k
FREQUENCY (Hz)
1M
1k 10k
FREQUENCY (Hz)
1M
1k 10k
1E+11E+21E+31E+41E+51E+61E0M+7
10 100
1M
1E+11E+21E+31E+41E+51E+61E0M+7
1E+11E+21E+31E+41E+51E+61E0M+7
10 100
100k
10 100
100k
100k
FREQUENCY (Hz)
Power Supply
Power Supply
Power Supply
Rejection Ratio
Rejection Ratio
Rejection Ratio
0
-20
0
-20
0
-20
VIN = 6V
VOUT = 5V
VIN = 6V
VOUT = 5V
VIN = 6V
VOUT = 5V
-40
-40
-40
-60
-60
-60
IOUT = 1mA
OUT = 2.2µF
BYP = 0.01µF
IOUT = 100µA
COUT = 2.2µF
CBYP = 0.01µF
IOUT = 100mA
COUT = 2.2µF
CBYP = 0.01µF
C
-80
-80
-80
C
-100
-100
-100
1k 10k
1M
1k 10k
1M
1k 10k
1E+11E+21E+31E+41E+51E+61E0M+7
10 100
1M
1E+11E+21E+31E+41E+51E+61E0M+7
1E+11E+21E+31E+41E+51E+61E0M+7
10 100
100k
10 100
100k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
Power Supply Ripple Rejection
Power Supply Ripple Rejection
vs. Voltage Drop
Noise Performance
vs. Voltage Drop
60
10
1
100
90
10mA, COUT = 1µF
50
80
70
60
50
40
30
20
10
0
1mA
1mA
40
0.1
IOUT = 100mA
30
20
10
0
10mA
IOUT = 100mA
0.01
0.001
0.0001
10mA
COUT = 2.2µF
CBYP = 0.01µF
COUT = 1µF
VOUT = 5V
10
0
0.1
0.2
0.3
0.4
1k
1E+111E0+021E+311E0+k411E0+05k11EM+611E0+M7
FREQUENCY (Hz)
0
0.1
0.2
0.3
0.4
VOLTAGE DROP (V)
VOLTAGE DROP (V)
Dropout Voltage
Noise Performance
Noise Performance
vs. Output Current
10
1
10
1
400
100mA
300
200
100
0
100mA
10mA
0.1
0.1
0.01
0.001
0.0001
0.01
0.001
0.0001
1mA
VOUT = 5V
VOUT = 5V
COUT = 10µF
1mA
COUT = 10µF
electrolytic
electrolytic
CBYP = 100pF
10mA
0
100 200 300 400 500
OUTPUT CURRENT (mA)
10
1k 10k 100k 1M 10M
10
1k 10k 100k 1M 10M
100
1E+11E+21E+31E+41E+51E+61E+7
FREQUENCY (Hz)
100
1E+11E+21E+31E+4 E+51E+61E+7
FREQUENCY (Hz)
June 2006
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Micrel, Inc.
Dropout Characteristics
Ground Current
vs. Output Current
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
12
10
8
I
=100µA
L
6
I =100mA
L
4
I =500mA
L
2
0
0
1
2
3
4
5
6
7
8
9
0
100 200 300 400 500
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
Ground Current
vs. Supply Voltage
Ground Current
vs. Supply Voltage
3.0
2.5
2.0
1.5
1.0
0.5
0
25
20
15
10
5
I =100 mA
L
I =100µ
L
I =500mA
L
0
A
8
0
2
4
6
0
1
2
3
4
5
6
7
8
9
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
M9999-060906
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June 2006
MIC5209
Micrel, Inc.
Thermal Considerations
Applications Information
The SOT-223 has a ground tab which allows it to dissipate
more power than the SO-8. Refer to “Slot-1 Power Supply”
for details. At 25°C ambient, it will operate reliably at 2W
dissipation with “worst-case” mounting (no ground plane,
minimum trace widths, and FR4 printed circuit board).
Enable/Shutdown
Enable is available only on devices in the SO-8 (M) and
TO-263-5 (U) packages.
ForcingEN(enable/shutdown)high(>2V)enablestheregula-
tor.ENiscompatiblewithCMOSlogic.Iftheenable/shutdown
feature is not required, connect EN to IN (supply input).
Thermal resistance values for the SO-8 represent typical
mounting on a 1”-square, copper-clad, FR4 circuit board.
For greater power dissipation, SO-8 versions of the MIC5209
feature a fused internal lead frame and die bonding arrange-
ment that reduces thermal resistance when compared to
standard SO-8 packages.
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
Package
JA
JC
An output capacitor is required between OUT and GND to
prevent oscillation. The minimum size of the output capacitor
is dependent upon whether a reference bypass capacitor is
used. 1µF minimum is recommended when C
(see Figure 1). 2.2µF minimum is recommended when C
SOT-223 (S)
SO-8 (M)
50°C/W
50°C/W
—
8°C/W
20°C/W
2°C/W
2°C/W
TO-263-5 (U)
3x3 MLF (ML)
is not used
BYP
63°C/W
BYP
is470pF(seeFigure2).Largervaluesimprovetheregulator’s
transient response.
Table 1. MIC5209 Thermal Resistance
Multilayer boards with a ground plane, wide traces near the
pads, andlargesupply-buslineswillhavebetterthermalcon-
ductivity and will also allow additional power dissipation.
The output capacitor should have an ESR (equivalent series
resistance) of about 1Ω and a resonant frequency above
1MHz. Ultra-low-ESR capacitors can cause a low amplitude
oscillation on the output and/or underdamped transient re-
sponse. 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.
For additional heat sink characteristics, please refer to Mi-
crel Application Hint 17, “Designing P.C. Board Heat Sinks”,
included in Micrel’s Databook. For a full discussion of heat
sinking and thermal effects on voltage regulators, refer to
Regulator Thermals section of Micrel’s Designing with Low-
Dropout Voltage Regulators handbook.
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.
Low-Voltage Operation
The MIC5209-1.8 and MIC5209-2.5 require special con-
sideration when used in voltage-sensitive systems. They
may momentarily overshoot their nominal output voltages
unless appropriate output and bypass capacitor values are
chosen.
No-Load Stability
TheMIC5209willremainstableandinregulationwithnoload
(other than the internal voltage divider) unlike many other
voltage regulators. This is especially important in CMOS
RAM keep-alive applications.
During regulator power up, the pass transistor is fully satu-
rated for a short time, while the error amplifier and voltage
reference are being powered up more slowly from the output
(see “Block Diagram”). Selecting larger output and bypass
capacitors allows additional time for the error amplifier and
reference to turn on and prevent overshoot.
Reference Bypass Capacitor
BYP (reference bypass) is available only on devices in SO-8
and TO-263-5 packages.
To ensure that no overshoot is present when starting up into
a light load (100µA), use a 4.7µF output capacitance and
470pF bypass capacitance. This slows the turn-on enough
to allow the regulator to react and keep the output voltage
from exceeding its nominal value. At heavier loads, use a
10µF output capacitance and 470pF bypass capacitance.
Lower values of output and bypass capacitance can be used,
depending on the sensitivity of the system.
BYP is connected to the internal voltage reference. A 470pF
capacitor (C
) connected from BYP to GND quiets this
BYP
reference, providing a significant reduction in output noise
(ultra-low-noise performance). Because C reduces the
BYP
phase margin, the output capacitor should be increased to
at least 2.2µF to maintain stability.
The start-up speed of the MIC5209 is inversely proportional
to the size of the reference bypass capacitor. Applications
requiring a slow ramp-up of output voltage should consider
Applicationsthatcanwithstandsomeovershootontheoutput
oftheregulatorcanreducetheoutputcapacitorand/orreduce
or eliminate the bypass capacitor. Applications that are not
sensitive to overshoot due to power-on reset delays can use
normal output and bypass capacitor configurations.
larger values of C . Likewise, if rapid turn-on is necessary,
BYP
consider omitting C
BYP
If output noise is not critical, omit C
open.
and leave BYP
BYP
Please note the junction temperature range of the regulator
at 1.8V output (fixed and adjustable) is 0˚C to +125˚C.
June 2006
9
M9999-060906
MIC5209
Micrel, Inc.
Fixed Regulator Circuits
MIC5209BM
VIN
VOUT
2
1
3
4
IN
OUT
ADJ
GND
IN
OUT
2
3
BYP
R1
R2
EN
1
4
2.2µF
EN
5–8
GND
5–8
470pF
Figure 1. Low-Noise Fixed Voltage Regulator
Figure 4. Ultra-Low-Noise Adjustable Application.
Figure1showsabasicMIC5209-x.xBM(SO-8)fixed-voltage
regulator circuit. See Figure 5 for a similar configuration us-
ing the more thermally-efficient MIC5209-x.xBS (SOT-223).
A 1µF minimum output capacitor is required for basic fixed-
voltage applications.
Figure 4 includes the optional 470pF bypass capacitor from
ADJ to GND to reduce output noise.
Slot-1 Power Supply
Intel’s Pentium II processors have a requirement for a 2.5V
±5% power supply for a clock synthesizer and its associated
loads. The current requirement for the 2.5V supply is depen-
dant upon the clock synthesizer used, the number of clock
outputs, and the type of level shifter (from core logic levels to
2.5V levels). Intel estimates a worst-case load of 320mA.
IN
OUT
2
3
1
4
The MIC5209 was designed to provide the 2.5V power
requirement for Slot-1 applications. Its guaranteed perfor-
mance of 2.5V ±3% at 500mA allows adequate margin for
all systems, and its dropout voltage of 500mV means that it
operates from a worst-case 3.3V supply where the voltage
can be as low as 3.0V.
5–8
470pF
Figure 2. Ultra-Low-Noise Fixed Voltage Regulator
Figure 2 includes the optional 470pF noise bypass capacitor
between BYP and GND to reduce output noise. Note that the
minimum value of C
capacitor is used.
must be increased when the bypass
OUT
IN
OUT
1
3
Adjustable Regulator Circuits
IN
OUT
IN
OUT
2,TAB
2
1
3
GND
4
R1
R2
Figure 5. Slot-1 Power Supply
5–8
A Slot-1 power supply (Figure 5) is easy to implement. Only
two capacitors are necessary, and their values are not criti-
cal. C bypasses the internal circuitry and should be at least
IN
0.1µF. C
provides output filtering, improves transient
Figure 3. Low-Noise Adjustable Voltage Regulator
OUT
response, and compensates the internal regulator control
The MIC5209BM/U can be adjusted to a specific output volt-
age by using two external resistors (Figure 3). The resistors
set the output voltage based on the equation:
loop. Its value should be at least 22µF. C and C
may
IN
OUT
be increased as much as desired.
Slot-1 Power Supply Power Dissipation
R2
R1
Powered from a 3.3V supply, the Slot-1 power supply of
Figure 5 has a nominal efficiency of 75%. At the maximum
anticipated Slot 1 load (320mA), the nominal power dissipa-
tion is only 256mW.
V
= 1.242V 1 +
OUT
This equation is correct due to the configuration of the
bandgap reference. The bandgap voltage is relative to the
output, as seen in the block diagram. Traditional regula-
tors normally have the reference voltage relative to ground;
therefore, their equations are different from the equation for
the MIC5209BM/U.
The SOT-223 package has sufficient thermal characteristics
for wide design margins when mounted on a single layer
copper-clad printed circuit board. The power dissipation of
the MIC5209 is calculated using the voltage drop across the
device output current plus supply voltage ground current.
AlthoughADJisahigh-impedanceinput,forbestperformance,
R2 should not exceed 470kΩ.
M9999-060906
10
June 2006
MIC5209
Micrel, Inc.
Considering worst case tolerances, the power dissipation
could be as high as:
Figure 6 shows the necessary copper pad area to obtain
specific heat sink thermal resistance (θ ) values. The θ
SA
SA
2
values in Table 2 require much less than 500mm of copper,
according to Figure 6, and can easily be accomplished with
the minimum footprint.
(V
– V
) I
+ V
I
IN(max)
OUT(max)
OUT
IN(max) GND
[(3.6V – 2.375V) 320mA] + (3.6V 4mA)
P = 407mW
D
70
60
50
40
30
20
10
0
Using the maximum junction temperature of 125°C and a θ
of 8°C/W for the SOT-223, 25°C/W for the SO-8, or 2°C/W
for the TO-263 package, the following worst-case heat-sink
JC
thermal resistance (θ ) requirements are:
SA
T
− T
J(max)
θ
JA
P
θ
= θ = θ
JC
T
40°C
50°C
60°C
75°C
θ
θ
θ
θ
JA (limit)
209°C/W
184°C/W 160°C/W 123°C/W
176°C/W 152°C/W 115°C/W
159°C/W 135°C/W 98°C/W
182°C/W 158°C/W 121°C/W
0
2000
4000
6000
2
COPPER HEAT SINK AREA (mm )
SOT-223 201°C/W
SO-8 184°C/W
TO-263-5 207°C/W
Figure 6. PCB Heat Sink Thermal Resistance
Table 2. Maximum Allowable Thermal Resistance
Table 2 and Figure 6 show that the Slot-1 power supply ap-
plicationcanbeimplementedwithaminimumfootprintlayout.
June 2006
11
M9999-060906
MIC5209
Micrel, Inc.
Package Information
SOT-223 (S)
8-Pin SOIC (M)
M9999-060906
12
June 2006
MIC5209
Micrel, Inc.
θ4
θ1
θ2
θ1
θ3
θ1
θ2
θ3
θ4
TO-263-5 (U)
8-Pin 3mm x 3mm MLF (ML)
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
This 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.
© 2004 Micrel Incorporated
June 2006
13
M9999-060906
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