datasheet for MIC5219
Micrel, Inc.
MIC5219
MIC5219
500mA-Peak Output LDO Regulator
General Description
Features
The MIC5219 is an eficient linear voltage regulator with high
peak output current capability, very-low-dropout voltage, and
better than 1% output voltage accuracy. Dropout is typically
10mV at light loads and less than 500mV at full load.
• 500mA output current capability
SOT-23-5 package - 500mA peak
2mm×2mm MLF® package - 500mA continuous
2mm×2mm Thin MLF® package - 500mA
continuous
MSOP-8 package - 500mA continuous
• Low 500mV maximum dropout voltage at full load
• Extremely tight load and line regulation
• Tiny SOT-23-5 and MM8™ power MSOP-8 package
• Ultra-low-noise output
• Low temperature coeficient
• Current and thermal limiting
• Reversed-battery protection
• CMOS/TTL-compatible enable/shutdown control
• Near-zero shutdown current
The MIC5219 is designed to provide a peak output current for
start-up conditions where higher inrush current is demanded.
It features a 500mA peak output rating. Continuous output
current is limited only by package and layout.
The MIC5219 can be enabled or shut down by a CMOS or
TTL compatible signal. When disabled, power consumption
drops nearly to zero. Dropout ground current is minimized to
help prolong battery life. Other key features include reversedbattery protection, current limiting, overtemperature shutdown,
and low noise performance with an ultra-low-noise option.
The MIC5219 is available in adjustable or ixed output voltages in the space-saving 6-pin (2mm × 2mm) MLF®, 6-pin
(2mm × 2mm) Thin MLF® SOT-23-5 and MM8® 8-pin power
MSOP packages. For higher power requirements see the
MIC5209 or MIC5237.
Applications
•
•
•
•
•
•
All support documentation can be found on Micrel’s web site
at www.micrel.com.
Laptop, notebook, and palmtop computers
Cellular telephones and battery-powered equipment
Consumer and personal electronics
PC Card VCC and VPP regulation and switching
SMPS post-regulator/DC-to-DC modules
High-eficiency linear power supplies
Typical Applications
MIC5219-5.0BMM
ENABLE
SH U TD OWN
VIN 6V
VOUT5V
2.2µF
tantalum
1
8
2
7
3
6
4
5
MIC5219-3.3BM5
VIN 4V
ENABLE
SHUTDOWN
EN
5
VOUT3.3V
2.2µF
tantalum
2
ENABLE
SH U TD OWN
4
3
470pF
470pF
5V Ultra-Low-Noise Regulator
VIN
1
VOUT
MIC5219-x.xYML
1
6
2
5
3
4
3.3V Ultra-Low-Noise Regulator
CBYP
VIN
ENABLE
SHUTDOWN
COUT
(optional)
EN
VOUT
MIC5219YMT
1
6
2
5
3
4
R1
+
2.2µF
R2
470pF
Ultra-Low-Noise Regulator (Adjustable)
Ultra-Low-Noise Regulator (Fixed)
MM8 is a registered trademark of Micrel, Inc.
MicroLeadFrame and MLF are registered trademarks of Amkor Technology, 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
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
Ordering Information
Part Number
Standard
Pb-Free
MIC5219-2.5BMM
MIC5219-2.5YMM
Marking
Standard
Pb-Free*
Volts
Temp. Range
Package
—
—
2.5V
–40°C to +125°C
MSOP-8
MIC5219-2.85BMM
MIC5219-2.85YMM
—
—
2.85V
–40°C to +125°C
MSOP-8
MIC5219-3.0BMM
MIC5219-3.0YMM
—
—
3.0V
–40°C to +125°C
MSOP-8
MIC5219-3.3BMM
MIC5219-3.3YMM
—
—
3.3V
–40°C to +125°C
MSOP-8
MIC5219-3.6BMM
MIC5219-3.6YMM
—
—
3.6V
–40°C to +125°C
MSOP-8
MIC5219-5.0BMM
MIC5219-5.0YMM
—
—
5.0V
–40°C to +125°C
MSOP-8
MIC5219BMM
MIC5219YMM
MIC5219-2.5BM5
MIC5219-2.5YM5
—
—
Adj.
–40°C to +125°C
MSOP-8
LG25
LG25
2.5V
–40°C to +125°C
SOT-23-5
MIC5219-2.6BM5
MIC5219-2.6YM5
LG26
MIC5219-2.7BM5
MIC5219-2.7YM5
LG27
LG26
2.6V
–40°C to +125°C
SOT-23-5
LG27
2.7V
–40°C to +125°C
SOT-23-5
MIC5219-2.8BM5
MIC5219-2.8YM5
LG28
MIC5219-2.8BML
MIC5219-2.8YML
G28
LG28
2.8V
–40°C to +125°C
SOT-23-5
G28
2.8V
–40°C to +125°C
6-Pin 2×2 MLF®
MIC5219-2.85BM5
MIC5219-2.85YM5
LG2J
LG2J
2.85V
–40°C to +125°C
SOT-23-5
MIC5219-2.9BM5
MIC5219-2.9YM5
LG29
LG29
2.9V
–40°C to +125°C
SOT-23-5
MIC5219-3.1BM5
MIC5219-3.1YM5
LG31
LG31
3.1V
–40°C to +125°C
SOT-23-5
MIC5219-3.0BM5
MIC5219-3.0YM5
LG30
LG30
3.0V
–40°C to +125°C
SOT-23-5
MIC5219-3.0BML
MIC5219-3.0YML
G30
G30
3.0V
–40°C to +125°C
6-Pin 2×2 MLF®
MIC5219-3.3BM5
MIC5219-3.3YM5
LG33
LG33
3.3V
–40°C to +125°C
SOT-23-5
MIC5219-3.3BML
MIC5219-3.3YML
G33
G33
3.3V
–40°C to +125°C
6-Pin 2×2 MLF®
MIC5219-3.6BM5
MIC5219-3.6YM5
LG36
LG36
3.6V
–40°C to +125°C
SOT-23-5
MIC5219-5.0BM5
MIC5219-5.0YM5
LG50
LG50
5.0V
–40°C to +125°C
SOT-23-5
MIC5219BM5
MIC5219YM5
LGAA
LGAA
Adj.
–40°C to +125°C
SOT-23-5
MIC5219YMT
GAA
Adj.
–40°C to +125°C
6-Pin 2x2 Thin MLF®**
MIC5219-5.0YMT
G50
5.0V
–40°C to +125°C
6-Pin 2x2 Thin MLF®**
Other voltages available. Consult Micrel for details.
* Over/underbar may not be to scale. ** Pin 1 identiier =
.
Pin Coniguration
EN 1
8 GND
IN 2
7 GND
EN 1
OUT 3
6 GND
GND 2
BYP 4
5 GND
IN 3
MIC5219-x.xBMM / MM8® / MSOP-8
Fixed Voltages
(Top View)
E N GND IN
6 BYP
4 OUT
MIC5219-x.xBML
6-Pin 2mm × 2mm MLF® (ML)
(Top View)
8 GND
IN 2
7 GND
EN 1
OUT 3
6 GND
GND 2
5 ADJ
BYP 4
5 GND
IN 3
4 OUT
June 2009
2
1
L Gx x
5 NC
EN 1
MIC5219YMM / MIC5219BMM
MM8® MSOP-8
Adjustable Voltage
(Top View)
3
4
5
BYP
OUT
MIC5219-x.xBM5 / SOT-23-5
Fixed Voltages
(Top View)
E N GND IN
6 NC
MIC5219YMT
6-Pin 2mm × 2mm Thin MLF® (MT)
(Top View)
2
3
2
1
Part
Identification
LGAA
4
5
ADJ
OUT
MIC5219BM5 / SOT-23-5
Adjustable Voltage
(Top View)
M0371-061809
Micrel, Inc.
MIC5219
Pin Description
Pin No.
MLF-6
TMLF-6
Pin No.
MSOP-8
Pin No.
SOT-23-5
Pin Name
Pin Function
3
2
1
IN
Supply Input.
2
5–8
2
GND
Ground: MSOP-8 pins 5 through 8 are internally connected.
4
3
5
OUT
Regulator Output.
1
1
3
EN
Enable (Input): CMOS compatible control input. Logic high = enable; logic
low or open = shutdown.
6
4 (ixed)
4 (ixed)
BYP
Reference Bypass: Connect external 470pF capacitor to GND to reduce
output noise. May be left open.
5(NC)
4 (adj.)
4 (adj.)
ADJ
Adjust (Input): Feedback input. Connect to resistive voltage-divider network.
EP
—
—
GND
Ground: Internally connected to the exposed pad. Connect externally to
GND pin.
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Input Voltage (VIN) ..............................–20V to +20V
Power Dissipation (PD) ............................. Internally Limited
Junction Temperature (TJ) ........................ –40°C to +125°C
Storage Temperature (TS) ........................ –65°C to +150°C
Lead Temperature (Soldering, 5 sec.) ....................... 260°C
Supply Input Voltage (VIN) ............................ +2.5V to +12V
Enable Input Voltage (VEN)....................................0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Package Thermal Resistance........................... see Table 1
Electrical Characteristics(3)
VIN = VOUT + 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.
Symbol
Parameter
Conditions
Min
VOUT
Output Voltage Accuracy
variation from nominal VOUT
VOUT/ T
ppm/°C
Output Voltage
Note 4
Typical
–1
–2
Max
Units
1
2
%
%
40
Temperature Coeficient
VOUT/VOUT
Line Regulation
VIN = VOUT + 1V to 12V
0.009
0.05
0.1
%/V
VOUT/VOUT
Load Regulation
IOUT = 100µA to 500mA, Note 5
0.05
0.5
0.7
%
Dropout Voltage(6)
IOUT = 100µA
10
60
80
mV
IOUT = 50mA
115
175
250
mV
IOUT = 150mA
175
300
400
mV
IOUT = 500mA
350
500
600
mV
VEN ≥ 3.0V, IOUT = 100µA
80
130
170
µA
VEN ≥ 3.0V, IOUT = 50mA
350
650
900
µA
VEN ≥ 3.0V, IOUT = 150mA
1.8
2.5
3.0
mA
VEN ≥ 3.0V, IOUT = 500mA
12
20
25
mA
VIN – VOUT
IGND
Ground Pin Current(7, 8)
Ground Pin Quiescent Current(8)
VEN ≤ 0.4V
0.05
3
µA
VEN ≤ 0.18V
0.10
8
µA
1000
mA
PSRR
Ripple Rejection
f = 120Hz
75
ILIMIT
Current Limit
VOUT = 0V
700
Note 9
0.05
%/W
IOUT = 50mA, COUT = 2.2µF, CBYP = 0
500
nV/ Hz
300
nV/ Hz
VOUT/ PD
eno
Thermal Regulation
Output Noise(10)
IOUT = 50mA, COUT = 2.2µF, CBYP = 470pF
dB
ENABLE Input
VENL
Enable Input Logic-Low Voltage
VEN = logic low (regulator shutdown)
IENL
Enable Input Current
VENL ≤ 0.4V
IENH
June 2009
VEN = logic high (regulator enabled)
VENL ≤ 0.18V
VENH ≥ 2.0V
4
0.4
0.18
V
0.01
–1
µA
0.01
–2
µA
5
20
25
µA
2.0
2
V
M0371-061809
Micrel, Inc.
MIC5219
Notes:
1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical speciications 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) = (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.
2. The device is not guaranteed to function outside its operating rating.
3. Speciication for packaged product only.
4. Output voltage temperature coeficient is deined as 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 speciication.
6. Dropout voltage is deined 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.
9. Thermal regulation is deined as the change in output voltage at a time “t” after a change in power dissipation is applied, excluding load or line regulation effects. Speciications are for a 500mA load pulse at VIN = 12V for t = 10ms.
10. CBYP is an optional, external bypass capacitor connected to devices with a BYP (bypass) or ADJ (adjust) pin.
June 2009
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Micrel, Inc.
MIC5219
Typical Characteristics
Power Supply
Rejection Ratio
0
Power Supply
Rejection Ratio
0
V IN = 6V
V OUT = 5V
-20
Power Supply
Rejection Ratio
0
V IN = 6V
V OUT = 5V
-20
-40
-40
-40
-60
-60
-60
-80
-80
IOUT = 100µA
C OUT = 1µF
-100
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100 1E+3
100k 1E+6
1E+1
FREQUENCY (Hz)
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
-20
-100
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100 1E+3
100k 1E+6
1E+1
FREQUENCY (Hz)
Power Supply Ripple Rejection
vs. Voltage Drop
0
V IN = 6V
V OUT = 5V
IOUT = 100mA
C OUT = 1µF
-80
IOUT = 1mA
C OUT = 1µF
-100
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100 1E+3
100k 1E+6
1E+1
FREQUENCY (Hz)
0
V IN = 6V
V OUT = 5V
-20
60
V IN = 6V
V OUT = 5V
-20
50
1mA
40
-40
-40
-60
-60
30
IOUT = 100µA
C OUT = 2.2µF
C BYP = 0.01µF
-80
-100
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100 1E+3
100k 1E+6
1E+1
FREQUENCY (Hz)
10
C OUT = 1µF
-100
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100 1E+3
100k 1E+6
1E+1
FREQUENCY (Hz)
Power Supply Ripple Rejection
vs. Voltage Drop
0
90
0.4
10
10mA, C
OUT
= 1µF
1
1
0.1
0.1
0.01
0.01
0.001
0.001
1mA
60
100mA
10mA
IOUT = 100mA
50
10mA
40
30
C OUT = 2.2µF
C BYP = 0.01µF
20
10
0
0.1
0.2
0.3
VOLTAGE DROP (V)
Noise Performance
10
80
70
0
Noise Performance
100
IOUT = 100mA
20
IOUT = 1mA
C OUT = 2.2µF
C BYP = 0.01µF
-80
10mA
0
0.1
0.2
0.3
VOLTAGE DROP (V)
0.4
V OUT = 5V
0.0001
10 1E+2
1k 1E+4
1E+1
100 1E+3
10k 1E+5
100k 1E+6
1M 1E+7
10M
FREQUENCY (Hz)
Dropout Characteristics
400
3.5
3.0
1
100mA
1mA
0.0001
1k 1E+4
10 1E+2
10k 1E+5
100k 1E+6
1M 1E+7
10M
1E+1
100 1E+3
FREQUENCY (Hz)
Dropout Voltage
vs. Output Current
Noise Performance
10
V OUT = 5V
C OUT = 10µF
electrolytic
300
I =100µA
L
2.5
0.1
2.0
200
0.01
0.001
V OUT = 5V
C OUT = 10µF
electrolytic
C BYP = 100pF
I =100mA
L
1.0
100
10mA
0.0001
1k 1E+4
10 1E+2
10k 1E+5
100k 1E+6
1M 1E+7
10M
1E+1
100 1E+3
FREQUENCY (Hz)
June 2009
1.5
1mA
I =500mA
L
0.5
0
0
100 200 300 400
OUTPUT CURRENT (mA)
6
500
0
0
1
2 3 4 5 6 7
INPUT VOLTAGE (V)
8
9
M0371-061809
Micrel, Inc.
MIC5219
Ground Current
vs. Output Current
Ground Current
vs. Supply Voltage
12
Ground Current
vs. Supply Voltage
3.0
25
10
2.5
20
8
2.0
15
6
1.5
IL =100 mA
10
4
1.0
5
2
0.5
I =100µA
L
IL =500mA
0
0
June 2009
100 200 300 400
OUTPUT CURRENT (mA)
500
0
0
1
2 3 4 5 6 7
INPUT VOLTAGE (V)
7
8
9
0
0
2
4
6
INPUT VOLTAGE (V)
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M0371-061809
Micrel, Inc.
MIC5219
Block Diagrams
VIN
OUT
IN
VOU T
COU T
BYP
CB Y P
(optional)
Bandgap
Ref.
V
REF
EN
Current Limit
Thermal Shutdown
MIC5219-x.xBM5/M/YMT
GND
Ultra-Low-Noise Fixed Regulator
VIN
OUT
IN
VOU T
R1
R2
Bandgap
Ref.
V
REF
COU T
CB Y P
(optional)
EN
Current Limit
Thermal Shutdown
MIC5219BM5/MM/YMT
GND
Ultra-Low-Noise Adjustable Regulator
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
Applications Information
Thermal Considerations
The MIC5219 is designed to provide 200mA of continuous
current in two very small proile packages. Maximum power
dissipation can be calculated based on the output current and
the voltage drop across the part. To determine the maximum
power dissipation of the package, use the thermal resistance,
junction-to-ambient, of the device and the following basic
equation.
The MIC5219 is designed for 150mA to 200mA output current
applications where a high current spike (500mA) is needed for
short, start-up conditions. Basic application of the device will
be discussed initially followed by a more detailed discussion
of higher current applications.
Enable/Shutdown
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). See Figure 5.
P D (max ) =
J
A
θ JA
TJ(max) is the maximum junction temperature of the die,
125°C, and TA is the ambient operating temperature. θJA
is layout dependent; Table 1 shows examples of thermal
resistance, junction-to-ambient, for the MIC5219.
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
ilter capacitor or if a battery is used as the input.
θJA Recommended
Minimum Footprint
θJA 1" Square฀
2oz. Copper
θJC
MM8® (MM)
160°C/W
70°C/W
30°C/W
SOT-23-5 (M5)
220°C/W
170°C/W
130°C/W
2×2 MLF® (ML)
90°C/W
—
—
90°C/W
—
—
Package
Output Capacitor
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 5). 2.2µF minimum is recommended when CBYP
is 470pF (see Figure 6). For applications < 3V, the output
capacitor should be increased to 22µF minimum to reduce
start-up overshoot. Larger values improve the regulator’s
transient response. The output capacitor value may be increased without limit.
2×2 Thin
MLF® (MT)
Table 1. MIC5219 Thermal Resistance
The actual power dissipation of the regulator circuit can be
determined using one simple equation.
PD = (VIN – VOUT) IOUT + VIN IGND
The output capacitor should have an ESR (equivalent series
resistance) of about 1 or less and a resonant frequency
above 1MHz. Ultra-low-ESR capacitors could cause oscillation and/or underdamped transient response. Most tantalum
or aluminum electrolytic capacitors are adequate; ilm types
will work, but are more expensive. Many aluminum electrolytics have electrolytes that freeze at about –30°C, so solid
tantalums are recommended for operation below –25°C.
Substituting PD(max) for PD and solving for the operating
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit. For
example, if we are operating the MIC5219-3.3BM5 at room
temperature, with a minimum footprint layout, we can determine the maximum input voltage for a set output current.
P D (max ) =
At lower values of output current, less output capacitance is
needed for stability. The capacitor can be reduced to 0.47µF
for current below 10mA, or 0.33µF for currents below 1mA.
(125 °C − 25°C )
220°C / W
PD(max) = 455mW
No-Load Stability
The thermal resistance, junction-to-ambient, for the minimum
footprint is 220°C/W, taken from Table 1. The maximum power
dissipation number cannot be exceeded for proper operation of the device. Using the output voltage of 3.3V, and an
output current of 150mA, we can determine the maximum
input voltage. Ground current, maximum of 3mA for 150mA
of output current, can be taken from the “Electrical Characteristics” section of the data sheet.
The MIC5219 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.
Reference Bypass Capacitor
BYP is connected to the internal voltage reference. A 470pF
capacitor (CBYP) connected from BYP to GND quiets this
reference, providing a signiicant reduction in output noise
(ultra-low-noise performance). CBYP reduces the regulator
phase margin; when using CBYP, output capacitors of 2.2µF
or greater are generally required to maintain stability.
455mW = (VIN – 3.3V) × 150mA + VIN × 3mA
455mW = (150mA) × VIN + 3mA × VIN – 495mW
950mW = 153mA × VIN
VIN = 6.2VMAX
The start-up speed of the MIC5219 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.
June 2009
( T (max ) − T )
Therefore, a 3.3V application at 150mA of output current
can accept a maximum input voltage of 6.2V in a SOT-23-5
package. For a full discussion of heat sinking and thermal
effects on voltage regulators, refer to the “Regulator Thermals” section of Micrel’s Designing with Low-Dropout Voltage
Regulators handbook.
9
M0371-061809
Micrel, Inc.
MIC5219
xBMM, the power MSOP package part. These graphs show
three typical operating regions at different temperatures. The
lower the temperature, the larger the operating region. The
graphs were obtained in a similar way to the graphs for the
MIC5219-x.xBM5, taking all factors into consideration and
using two different board layouts, minimum footprint and 1"
square copper PC board heat sink. (For further discussion
of PC board heat sink characteristics, refer to “Application
Hint 17, Designing PC Board Heat Sinks” .)
Peak Current Applications
The MIC5219 is designed for applications where high start-up
currents are demanded from space constrained regulators.
This device will deliver 500mA start-up current from a SOT23-5 or MM8 package, allowing high power from a very low
proile device. The MIC5219 can subsequently provide output
current that is only limited by the thermal characteristics of
the device. You can obtain higher continuous currents from
the device with the proper design. This is easily proved with
some thermal calculations.
The information used to determine the safe operating regions
can be obtained in a similar manner such as determining
typical power dissipation, already discussed. Determining
the maximum power dissipation based on the layout is the
irst step, this is done in the same manner as in the previous
two sections. Then, a larger power dissipation number multiplied by a set maximum duty cycle would give that maximum
power dissipation number for the layout. This is best shown
through an example. If the application calls for 5V at 500mA
for short pulses, but the only supply voltage available is
8V, then the duty cycle has to be adjusted to determine an
average power that does not exceed the maximum power
dissipation for the layout.
If we look at a speciic example, it may be easier to follow.
The MIC5219 can be used to provide up to 500mA continuous
output current. First, calculate the maximum power dissipation of the device, as was done in the thermal considerations
section. Worst case thermal resistance (θJA = 220°C/W for
the MIC5219-x.xBM5), will be used for this example.
P D (max ) =
( T (max ) − T )
J
A
θ JA
Assuming a 25°C room temperature, we have a maximum
power dissipation number of
P D (max ) =
(125 °C − 25°C )
฀% DC ฀
Avg.P D = ฀
฀ V – V OUT I OUT + V IN I GND
฀ 100 ฀ IN
(
220 °C / W
PD(max) = 455mW
฀% DC ฀
455mW = ฀
฀ (8V – 5V ) 500mA + 8V × 20mA
฀ 100 ฀
Then we can determine the maximum input voltage for a
5-volt regulator operating at 500mA, using worst case ground
current.
฀% Duty Cycle ฀
455mW = ฀
฀ 1.66W
฀
100
฀
PD(max) = 455mW = (VIN – VOUT) IOUT + VIN IGND
IOUT = 500mA
0.274 =
IGND = 20mA
% Duty Cycle Max
VOUT = 5V
455mW = (VIN – 5V) 500mA + VIN × 20mA
% Duty Cycle
100
= 27.4%
With an output current of 500mA and a three-volt drop across
the MIC5219-xxBMM, the maximum duty cycle is 27.4%.
2.995W = 520mA × VIN
VIN (max ) =
)
Applications also call for a set nominal current output with a
greater amount of current needed for short durations. This is a
tricky situation, but it is easily remedied. Calculate the average
power dissipation for each current section, then add the two
numbers giving the total power dissipation for the regulator.
For example, if the regulator is operating normally at 50mA,
but for 12.5% of the time it operates at 500mA output, the
total power dissipation of the part can be easily determined.
First, calculate the power dissipation of the device at 50mA.
We will use the MIC5219-3.3BM5 with 5V input voltage as
our example.
2.955W
= 5.683V
520mA
Therefore, to be able to obtain a constant 500mA output current from the 5219-5.0BM5 at room temperature, you need
extremely tight input-output voltage differential, barely above
the maximum dropout voltage for that current rating.
You can run the part from larger supply voltages if the proper
precautions are taken. Varying the duty cycle using the enable pin can increase the power dissipation of the device by
maintaining a lower average power igure. This is ideal for
applications where high current is only needed in short bursts.
Figure 1 shows the safe operating regions for the MIC5219-x.
xBM5 at three different ambient temperatures and at different output currents. The data used to determine this igure
assumed a minimum footprint PCB design for minimum heat
sinking. Figure 2 incorporates the same factors as the irst
igure, but assumes a much better heat sink. A 1" square copper trace on the PC board reduces the thermal resistance of
the device. This improved thermal resistance improves power
dissipation and allows for a larger safe operating region.
PD × 50mA = (5V – 3.3V) × 50mA + 5V × 650µA
PD × 50mA = 173mW
However, this is continuous power dissipation, the actual
on-time for the device at 50mA is (100%-12.5%) or 87.5%
of the time, or 87.5% duty cycle. Therefore, PD must be multiplied by the duty cycle to obtain the actual average power
dissipation at 50mA.
Figures 3 and 4 show safe operating regions for the MIC5219-x.
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
10
10
10
100mA
8
100mA
8
6
6
200mA
100mA
8
6
200mA
300mA
4
4
400mA
2
2
0
20
40
60
80
DUTY CYCLE (%)
100
0
500mA
0
a. 25°C Ambient
20
300mA
2 500mA
400mA
500mA
0
200mA
4
300mA
40
60
80
DUTY CYCLE (%)
100
0
400mA
0
b. 50°C Ambient
20
40
60
80
DUTY CYCLE (%)
100
c. 85°C Ambient
Figure 1. MIC5219-x.xBM5 (SOT-23-5) on Minimum Recommended Footprint
10
10
10
100mA
8
8
8
100mA
100mA
200mA
6
6
300mA
4
400mA
2
200mA
4
0
20
2
40
60
80
DUTY CYCLE (%)
100
0
200mA
4
300mA
500mA
0
a. 25°C Ambient
20
300mA
2 400mA
400mA
500mA
0
6
40
60
80
DUTY CYCLE (%)
100
0
500mA
0
b. 50°C Ambient
20
40
60
80
DUTY CYCLE (%)
100
c. 85°C Ambient
Figure 2. MIC5219-x.xBM5 (SOT-23-5) on 1-inch2 Copper Cladding
10
10
10
100mA
100mA
8
8
200mA
6
8
6
100mA
6
200mA
200mA
300mA
4
300mA
4
300mA
4
400mA
2
400mA
2
500mA
0
0
20
2
400mA
500mA
40
60
80
DUTY CYCLE (%)
100
0
0
a. 25°C Ambient
20
40
60
80
DUTY CYCLE (%)
100
0
500mA
0
b. 50°C Ambient
20
40
60
80
DUTY CYCLE (%)
100
c. 85°C Ambient
Figure 3. MIC5219-x.xBMM (MSOP-8) on Minimum Recommended Footprint
10
200mA
8
10
10
300mA
6
6
400mA
4
8
200mA
6
300mA
400mA
4
500mA
2
100mA
200mA
8
300mA
4
500mA
2
400mA
2
500mA
0
0
20
40
60
80
DUTY CYCLE (%)
a. 25°C Ambient
100
0
0
20
40
60
80
DUTY CYCLE (%)
b. 50°C Ambient
100
0
0
20
40
60
80
DUTY CYCLE (%)
100
c. 85°C Ambient
Figure 4. MIC5219-x.xBMM (MSOP-8) on 1-inch2 Copper Cladding
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Micrel, Inc.
MIC5219
PD × 50mA = 0.875 × 173mW
VIN
PD × 50mA = 151mW
The power dissipation at 500mA must also be calculated.
PD × 500mA = (5V – 3.3V) 500mA + 5V × 20mA
IN
EN
This number must be multiplied by the duty cycle at which it
would be operating, 12.5%.
2.2µF
Figure 6. Ultra-Low-Noise Fixed Voltage Regulator
PD × = 0.125 × 950mW
Figure 6 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.
PD × = 119mW
The total power dissipation of the device under these conditions is the sum of the two power dissipation igures.
Adjustable Regulator Circuits
MIC5219
VIN
IN
OUT
EN
ADJ
GND
PD(total) = PD × 50mA + PD × 500mA
PD(total) = 151mW + 119mW
PD(total) = 270mW
The total power dissipation of the regulator is less than the
maximum power dissipation of the SOT-23-5 package at room
temperature, on a minimum footprint board and therefore
would operate properly.
VOU T
R1
1µF
R2
Multilayer boards with a ground plane, wide traces near the
pads, and large supply-bus lines will have better thermal
conductivity.
Figure 7. Low-Noise Adjustable Voltage Regulator
Figure 7 shows the basic circuit for the MIC5219 adjustable
regulator. The output voltage is conigured by selecting values
for R1 and R2 using the following formula:
฀R2
฀
V OUT = 1.242V ฀ + 1฀
฀R1
฀
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.
Although ADJ is a high-impedance input, for best performance,
R2 should not exceed 470k .
MIC5219
VIN
VOU T
IN
OUT
R1
EN
ADJ
GND
2.2µF
VOU T
1µF
470pF
Figure 5. Low-Noise Fixed Voltage Regulator
R2
Figure 8. Ultra-Low-Noise Adjustable Application
Figure 5 shows a basic MIC5219-x.xBMX ixed-voltage regulator circuit. A 1µF minimum output capacitor is required for
basic ixed-voltage applications.
June 2009
VOU T
OUT
BYP
GND
470pF
PD × 500mA = 950mW
Fixed Regulator Circuits
MIC5219-x.x
VIN
IN
OUT
EN
BYP
GND
MIC5219-x.x
Figure 8 includes the optional 470pF bypass capacitor from
ADJ to GND to reduce output noise.
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Micrel, Inc.
MIC5219
Package Information
8-Pin MSOP (MM)
SOT-23-5 (M5)
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
6-Pin MLF® (ML)
6-Pin Thin MLF® (MT)
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
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 speciications at any time without notiication 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 signiicant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2005 Micrel, Incorporated.
June 2009
14
M0371-061809
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