Micrel MIC5209-3.6YU 500ma low-noise ldo regulator Datasheet

MIC5209
500mA Low-Noise LDO Regulator
General Description
Features
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
Designed especially for hand-held, battery-powered devices,
the MIC5209 features low ground current to help prolong
battery life. An enable/shutdown pin on SO-8 and TO-2635 versions can further improve battery life with near-zero
shutdown current.
Key features include reversed-battery protection, current
limiting, overtemperature shutdown, ultra-low-noise capability
(SO-8 and TO-263-5 versions), and availability in thermally
efficient packaging. The MIC5209 is available in adjustable
or fixed output voltages.
Applications
•
•
•
•
•
•
For space-critical applications where peak currents do not
exceed 500mA, see the MIC5219.
Pentium II Slot 1 and Slot 2 support circuits
Laptop, notebook, and palmtop computers
Cellular telephones
Consumer and personal electronics
SMPS post-regulator/dc-to-dc modules
High-efficiency linear power supplies
Typical Applications
MIC5209-2.5BS
VIN
≥ 3.0V
1
2
3
0.1µF
VOUT
2.5V ±1%
22µF
tantalum
3.3V Nominal-Input Slot-1
Power Supply
ENABLE
SHUTDOWN
VIN
6V
VOUT
5V
2.2µF
tantalum
1
MIC5209-5.0BM
8
2
7
3
6
4
5
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
Voltage
Junction Temp. Range
Package
Pb-Free
MIC5209-2.5BS
2.5V
-40°C to +125°C
SOT-223
MIC5209-2.5YS
2.5V
-40°C to +125°C
SOT-223
MIC5209-3.0BS
3.0V
-40°C to +125°C
SOT-223
MIC5209-3.0YS
3.0V
-40°C to +125°C
SOT-223
MIC5209-3.3BS
3.3V
-40°C to +125°C
SOT-223
MIC5209-3.3YS
3.3V
-40°C to +125°C
SOT-223
MIC5209-3.6BS
3.6V
-40°C to +125°C
SOT-223
MIC5209-3.6YS
3.6V
-40°C to +125°C
SOT-223
MIC5209-4.2BS
4.2V
-40°C to +125°C
SOT-223
MIC5209-4.2YS
4.2V
-40°C to +125°C
SOT-223
MIC5209-5.0BS
5.0V
-40°C to +125°C
SOT-223
MIC5209-5.0YS
5.0V
-40°C to +125°C
SOT-223
MIC5209-1.8BM*
1.8V
-0°C to +125°C
SOIC-8
MIC5209-1.8YM*
1.8V
-0°C to +125°C
SOIC-8
MIC5209-2.5BM
2.5V
-40°C to +125°C
SOIC-8
MIC5209-2.5YM
2.5V
-40°C to +125°C
SOIC-8
MIC5209-3.0BM
3.0V
-40°C to +125°C
SOIC-8
MIC5209-3.0YM
3.0V
-40°C to +125°C
SOIC-8
MIC5209-3.3BM
3.3V
-40°C to +125°C
SOIC-8
MIC5209-3.3YM
3.3V
-40°C to +125°C
SOIC-8
MIC5209-3.6BM
3.6V
-40°C to +125°C
SOIC-8
MIC5209-3.6YM
3.6V
-40°C to +125°C
SOIC-8
MIC5209-5.0BM
5.0V
-40°C to +125°C
SOIC-8
MIC5209-5.0YM
5.0V
-40°C to +125°C
SOIC-8
MIC5209BM
Adj.
-40°C to +125°C
SOIC-8
MIC5209YM
Adj.
-40°C to +125°C
SOIC-8
X
MIC5209-1.8YU*
1.8V
-0°C to +125°C
TO-263-5
X
MIC5209-2.5BU
2.5V
-40°C to +125°C
TO-263-5
MIC5209-2.5YU
2.5V
-40°C to +125°C
TO-263-5
MIC5209-3.0BU
3.0V
-40°C to +125°C
TO-263-5
MIC5209-3.0YU
3.0V
-40°C to +125°C
TO-263-5
MIC5209-3.3BU
3.3V
-40°C to +125°C
TO-263-5
MIC5209-3.3YU
3.3V
-40°C to +125°C
TO-263-5
MIC5209-3.6BU
3.6V
-40°C to +125°C
TO-263-5
MIC5209-3.6YU
3.6V
-40°C to +125°C
TO-263-5
MIC5209-5.0BU
5.0V
-40°C to +125°C
TO-263-5
MIC5209-5.0YU
5.0V
-40°C to +125°C
TO-263-5
MIC5209BU
Adj.
-40°C to +125°C
TO-263-5
MIC5209YU
Adj.
-40°C to +125°C
TO-263-5
X
MIC5209YML
Adj.
-40°C to +125°C
8-pin MLF™
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
* Contact marketing for availability.
M9999-060906
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June 2006
MIC5209
Micrel, Inc.
Pin Configuration
GND
TAB
VIN 1
VIN 2
VOUT 3
1
IN
2
VOUT 4
3
Y
5209
YWW
8
EN
7
GND
6
ADJ
5
NC
Part
Identification
GND OUT
MIC5209-x.xBS
SOT-223
Fixed Voltages
8
GND
IN 2
7
GND
OUT 3
6
GND
BYP 4
5
GND
TAB
EN 1
GND
MIC5209YML
8-Pin 3x3 MLF
Adjustable Voltages
5
4
3
2
1
BYP
OUT
GND
IN
EN
5
4
3
2
1
ADJ
OUT
GND
IN
EN
MIC5209-x.xBU
TO-263-5
Fixed Voltages
8
GND
IN 2
7
GND
OUT 3
6
GND
ADJ 4
5
GND
TA
AB
EN 1
GND
MIC5209-x.xBM
SO-8
Fixed Voltages
MIC5209BU
TO-263-5
Adjustable Voltage
MIC5209BM
SO-8
Adjustable Voltage
Pin Description
Pin No.
8-pin MLF
Pin No.
SOT-223
Pin No.
SO-8
Pin No.
TO-263-5
Pin Name
Pin Function
1, 2
1
2
2
IN
Supply Input.
7
2, TAB
5–8
3
GND
Ground: SOT-223 pin 2 and TAB are internally connected. SO-8
pins 5 through 8 are internally connected.
3, 4
3
3
4
OUT
Regulator Output. Pins 3 and 4 must be tied together.
1
1
EN
Enable (Input): CMOS compatible control input. Logic high =
enable; logic low = shutdown.
4 (fixed)
5 (fixed)
BYP
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.”
4 (adj.)
5 (adj.)
ADJ
Adjust (Input): Feedback input. Connect to resistive voltage-divider
network.
8
6
June 2006
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M9999-060906
MIC5209
Micrel, Inc.
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Input Voltage (VIN) ..............................–20V to +20V
Power Dissipation (PD) ..........................Internally Limited(3)
Junction Temperature (TJ)
all except 1.8V ...................................... –40°C to +125°C
1.8V only................................................... 0°C to +125°C
Lead Temperature (soldering, 5 sec.) ........................ 260°C
Storage Temperature (TS) ........................ –65°C to +150°C
Supply Input Voltage (VIN) ............................ +2.5V to +16V
Enable Input Voltage (VEN) ...................................0V to VIN
Junction Temperature (TJ)
all except 1.8V ...................................... –40°C to +125°C
1.8V only................................................... 0°C to +125°C
Package Thermal Resistance................................... Note 3
Electrical Characteristics (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
VOUT
Output Voltage Accuracy
variation from nominal VOUT
ΔVOUT/ΔT
Output Voltage
Temperature Coefficient
Note 4
ΔVOUT/VOUT
Line Regulation
VIN = VOUT + 1V to 16V
0.009
0.05
0.1
%/V
%/V
ΔVOUT/VOUT
Load Regulation
IOUT = 100µA to 500mA(5)
0.05
0.5
0.7
%
%
VIN – VOUT
Dropout Voltage(6)
IOUT = 100µA
10
60
80
mV
mV
IOUT = 50mA
115
175
250
mV
mV
IOUT = 150mA
165
300
400
mV
mV
IOUT = 500mA
350
500
600
mV
mV
VEN ≥ 3.0V, IOUT = 100µA
80
130
170
µA
µA
VEN ≥ 3.0V, IOUT = 50mA
350
650
900
µA
µA
VEN ≥ 3.0V, IOUT = 150mA
1.8
2.5
3.0
mA
mA
VEN ≥ 3.0V, IOUT = 500mA
8
20
25
mA
mA
IGND
IGND
Ground Pin Current(7, 8)
Ground Pin Quiescent Current(8)
Min
Typical
–1
–2
Max
Units
1
2
%
%
40
ppm/°C
0.05
3
µA
VEN ≤ 0.18V (shutdown)
0.10
8
µA
900
1000
mA
mA
VEN ≤ 0.4V (shutdown)
PSRR
Ripple Rejection
f = 120Hz
75
ILIMIT
Current Limit
VOUT = 0V
700
ΔVOUT/ΔPD
Thermal Regulation
Note 9
0.05
%/W
VOUT = 2.5V, IOUT = 50mA,
COUT = 2.2µF, CBYP = 0
500
nV √Hz
300
nV √Hz
eno
Output
Noise(10)
IOUT = 50mA, COUT = 2.2µF, CBYP = 470pF
M9999-060906
4
dB
June 2006
MIC5209
Micrel, Inc.
ENABLE Input
VENL
Enable Input Logic-Low Voltage
VEN = logic low (regulator shutdown)
IENL
Enable Input Current
VENL ≤ 0.4V
IENH
VEN = logic high (regulator enabled)
VENL ≤ 0.18V
0.4
0.18
V
V
0.01
–1
µA
0.01
–2
µA
5
20
25
µA
µA
30
50
µA
µA
2.0
V
VENH = 2.0V
VENH = 16V
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 differential.
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 effects. 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
VIN
VOUT
COUT
Bandgap
Ref.
Current Limit
Thermal Shutdown
MIC5209-x.xBS
GND
Low-Noise Fixed Regulator (SOT-223 version only)
VIN
OUT
IN
VOUT
COUT
BYP
CBYP
(optional)
Bandgap
Ref.
V
REF
EN
Current Limit
Thermal Shutdown
MIC5209-x.xBM/U
GND
Ultra-Low-Noise Fixed Regulator
VIN
OUT
IN
VOUT
COUT
ADJ
Bandgap
Ref.
V
REF
R1
R2
CBYP
(optional)
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
Rejection Ratio
-80
-20
PSRR (dB)
-20
PSRR (dB)
0
VIN = 6V
VOUT = 5V
-40
-60
IOUT = 100µA
COUT = 2.2µF
CBYP = 0.01µF
-80
30
IOUT = 100mA
20
10
0
10
1
NOISE (µV/√Hz)
1mA
10mA
0.1
COUT = 1µF
0.1
0.2
0.3
VOLTAGE DROP (V)
PSRR (dB)
-60
RIPPLE REJECTION (dB)
40
0.4
Noise Performance
10
IOUT = 1mA
COUT = 2.2µF
CBYP = 0.01µF
10mA
0.01
VOUT = 5V
1mA
0.001 C
OUT = 10µF
electrolytic
0.0001
1k 10k 1E+51E+6
10 1E+2
100k 1M 1E+7
10M
100 1E+31E+4
1E+1
FREQUENCY (Hz)
-40
-60
IOUT = 100mA
COUT = 2.2µF
CBYP = 0.01µF
-80
-100
10k 100k1E+61E+7
1M 10M
1E+1
10 1E+21E+3
100 1k 1E+41E+5
FREQUENCY (Hz)
10
1
1mA
10mA
IOUT = 100mA
COUT = 2.2µF
CBYP = 0.01µF
0.1
0.2
0.3
VOLTAGE DROP (V)
Noise Performance
10mA, COUT = 1µF
0.1
0.01
0.001
0.4
Noise Performance
1
100mA
NOISE (µV/√Hz)
RIPPLE REJECTION (dB)
50
VIN = 6V
VOUT = 5V
-20
-40
100
90
80
70
60
50
40
30
20
10
0
0
Power Supply
Rejection Ratio
0
VIN = 6V
VOUT = 5V
Power Supply Ripple Rejection
vs. Voltage Drop
60
IOUT = 100mA
COUT = 1µF
-100
10k 100k1E+61E+7
1M 10M
1E+1
10 1E+21E+3
100 1k 1E+41E+5
FREQUENCY (Hz)
-100
10k 100k1E+61E+7
1M 10M
1E+1
10 1E+21E+3
100 1k 1E+41E+5
FREQUENCY (Hz)
Power Supply Ripple Rejection
vs. Voltage Drop
-60
Power Supply
Rejection Ratio
-80
-100
10k 100k1E+61E+7
1M 10M
1E+1
10 1E+21E+3
100 1k 1E+41E+5
FREQUENCY (Hz)
-40
-80
IOUT = 1mA
COUT = 1µF
-100
10k 100k1E+61E+7
1M 10M
1E+1
10 1E+21E+3
100 1k 1E+41E+5
FREQUENCY (Hz)
Power Supply
Rejection Ratio
0
June 2006
-60
-80
IOUT = 100µA
COUT = 1µF
-100
10k 100k1E+61E+7
1M 10M
1E+1
10 1E+21E+3
100 1k 1E+41E+5
FREQUENCY (Hz)
0
-40
PSRR (dB)
-60
VIN = 6V
VOUT = 5V
-20
NOISE (µV/√Hz)
-40
0
VIN = 6V
VOUT = 5V
-20
PSRR (dB)
-20
PSRR (dB)
0
VIN = 6V
VOUT = 5V
Power Supply
Rejection Ratio
100mA
0.1
VOUT = 5V
0.0001
10 100 1E+31E+4
1k 10k 1E+51E+6
100k 1M 1E+7
10M
1E+11E+2
FREQUENCY (Hz)
400
Dropout Voltage
vs. Output Current
DROPOUT VOLTAGE (mV)
0
Power Supply
Rejection Ratio
300
200
0.01 V
OUT = 5V
COUT = 10µF
0.001 electrolytic
CBYP = 100pF
1mA
10mA
0.0001
10 1E+21E+3
1M 10M
10k 100k 1E+61E+7
100 1k 1E+41E+5
1E+1
FREQUENCY (Hz)
7
100
0
0
100 200 300 400 500
OUTPUT CURRENT (mA)
M9999-060906
MIC5209
Micrel, Inc.
Dropout Characteristics
OUTPUT VOLTAGE (V)
3.0
12
IL =100µA
GROUND CURRENT (mA)
3.5
10
2.5
2.0
1.5
IL=100mA
1.0
IL=500mA
0.5
GROUND CURRENT (mA)
25
1
2 3 4 5 6 7 8
INPUT VOLTAGE (V)
6
4
2
0
0
9
Ground Current
vs. Supply Voltage
3.0
100 200 300 400 500
OUTPUT CURRENT (mA)
Ground Current
vs. Supply Voltage
2.5
20
2.0
15
1.5
10
1.0
5
0
0
M9999-060906
8
GROUND CURRENT (mA)
0
0
Ground Current
vs. Output Current
IL=500mA
1 2 3 4 5 6 7 8
INPUT VOLTAGE (V)
0.5
0
0
9
8
IL=100 mA
IL=100µ
A8
4
6
2
INPUT VOLTAGE (V)
June 2006
MIC5209
Micrel, Inc.
Applications Information
Thermal Considerations
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.
Forcing EN (enable/shutdown) high (> 2V) enables the regulator. EN is compatible with CMOS logic. If the enable/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 arrangement 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
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 CBYP is not used
(see Figure 1). 2.2µF minimum is recommended when CBYP
is 470pF (see Figure 2). Larger values improve the regulator’s
transient response.
θJA
θJC
SOT-223 (S)
50°C/W
8°C/W
SO-8 (M)
50°C/W
20°C/W
TO-263-5 (U)
—
2°C/W
3x3 MLF (ML)
63°C/W
2°C/W
Table 1. MIC5209 Thermal Resistance
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 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.
Multilayer boards with a ground plane, wide traces near the
pads, and large supply-bus lines will have better thermal conductivity and will also allow additional power dissipation.
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
For additional heat sink characteristics, please refer to Micrel 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 LowDropout Voltage Regulators handbook.
The MIC5209-1.8 and MIC5209-2.5 require special consideration 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
The MIC5209 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 CMOS
RAM keep-alive applications.
During regulator power up, the pass transistor is fully saturated 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 (CBYP) connected from BYP to GND quiets this
reference, providing a significant reduction in output noise
(ultra-low-noise performance). Because CBYP reduces the
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
larger values of CBYP. Likewise, if rapid turn-on is necessary,
consider omitting CBYP.
Applications that can withstand some overshoot on the output
of the regulator can reduce the output capacitor and/or reduce
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.
If output noise is not critical, omit CBYP and leave BYP
open.
June 2006
Please note the junction temperature range of the regulator
at 1.8V output (fixed and adjustable) is 0˚C to +125˚C.
9
M9999-060906
MIC5209
Micrel, Inc.
Fixed Regulator Circuits
MIC5209-x.xBM
VIN
2
3
IN
OUT
1
4
EN
BYP
GND
5–8
VIN
VOUT
MIC5209BM
2
1
IN
EN
OUT
ADJ
GND
VOUT
3
4
R1
5–8
1µF
470pF
2.2µF
R2
Figure 1. Low-Noise Fixed Voltage Regulator
Figure 4. Ultra-Low-Noise Adjustable Application.
Figure 1 shows a basic MIC5209-x.xBM (SO-8) fixed-voltage
regulator circuit. See Figure 5 for a similar configuration using the more thermally-efficient MIC5209-x.xBS (SOT-223).
A 1µF minimum output capacitor is required for basic fixedvoltage applications.
Figure 4 includes the optional 470pF bypass capacitor from
ADJ to GND to reduce output noise.
MIC5209-x.xBM
VIN
2
1
IN
OUT
EN
BYP
GND
5–8
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 dependant 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.
VOUT
3
4
2.2µF
The MIC5209 was designed to provide the 2.5V power
requirement for Slot-1 applications. Its guaranteed performance 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.
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 COUT must be increased when the bypass
capacitor is used.
VIN
Adjustable Regulator Circuits
VIN
MIC5209BM
2
1
IN
EN
OUT
ADJ
GND
5–8
3
4
CIN
0.1µF
VOUT
R1
IN
OUT
GND
2,TAB
3
VOUT
COUT
22µF
Figure 5. Slot-1 Power Supply
1µF
A Slot-1 power supply (Figure 5) is easy to implement. Only
two capacitors are necessary, and their values are not critical. CIN bypasses the internal circuitry and should be at least
0.1µF. COUT provides output filtering, improves transient
response, and compensates the internal regulator control
loop. Its value should be at least 22µF. CIN and COUT may
be increased as much as desired.
R2
Figure 3. Low-Noise Adjustable Voltage Regulator
The MIC5209BM/U can be adjusted to a specific output voltage by using two external resistors (Figure 3). The resistors
set the output voltage based on the equation:
R2 

VOUT = 1.242V 1 +


R1
Slot-1 Power Supply Power Dissipation
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 dissipation is only 256mW.
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 regulators 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.
Although ADJ is a high-impedance input, for best performance,
R2 should not exceed 470kΩ.
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MIC5209-x.xBS
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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 (θSA) values. The θSA
values in Table 2 require much less than 500mm2 of copper,
according to Figure 6, and can easily be accomplished with
the minimum footprint.
(VIN(max) – VOUT(max)) × IOUT + VIN(max) × IGND
[(3.6V – 2.375V) × 320mA] + (3.6V × 4mA)
PD = 407mW
Using the maximum junction temperature of 125°C and a θJC
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
thermal resistance (θSA) requirements are:
TJ(max
J(max) − TA
θJA =
PD
70
60
50
40
30
θSA = θJA = θJC
TA
20
40°C
50°C
60°C
75°C
θJA (limit)
209°C/W
184°C/W
160°C/W
123°C/W
θSA SOT-223
201°C/W
176°C/W
152°C/W
115°C/W
θSA SO-8
184°C/W
159°C/W
135°C/W
98°C/W
θSA TO-263-5
207°C/W
182°C/W
158°C/W
121°C/W
10
0
0
2000
4000
6000
COPPER HEAT SINK AREA (mm2)
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 application can be implemented with a minimum footprint layout.
June 2006
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M9999-060906
MIC5209
Micrel, Inc.
Package Information
SOT-223 (S)
8-Pin SOIC (M)
M9999-060906
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June 2006
MIC5209
Micrel, Inc.
θ4
θ1
θ2
θ1
θ1
θ2
θ3
θ4
θ1
θ3
TO-263-5 (U)
8-Pin 3mm x 3mm MLF (ML)
MICREL INC.
TEL
2180 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
+ 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
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M9999-060906