MIC5219-3.6YM5 [MICREL]
500mA-Peak Output LDO Regulator; 值为500mA的峰值输出LDO稳压器型号: | MIC5219-3.6YM5 |
厂家: | MICREL SEMICONDUCTOR |
描述: | 500mA-Peak Output LDO Regulator |
文件: | 总14页 (文件大小:385K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
MIC5219
500mA-Peak Output LDO Regulator
General Description
Features
The MIC5219 is an efficient 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
TheMIC5219isdesignedtoprovideapeakoutputcurrentfor
start-upconditionswherehigherinrushcurrentisdemanded.
It features a 500mA peak output rating. Continuous output
current is limited only by package and layout.
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 coefficient
• Current and thermal limiting
• Reversed-battery protection
• CMOS/TTL-compatible enable/shutdown control
• Near-zero shutdown current
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
helpprolongbatterylife.Otherkeyfeaturesincludereversed-
batteryprotection,currentlimiting,overtemperatureshutdown,
and low noise performance with an ultra-low-noise option.
The MIC5219 is available in adjustable or fixed output volt-
®
Applications
• Laptop, notebook, and palmtop computers
• Cellular telephones and battery-powered equipment
• Consumer and personal electronics
ages 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.
• PC Card V and V regulation and switching
• SMPS post-regulator/DC-to-DC modules
• High-efficiency linear power supplies
All support documentation can be found on Micrel’s web site
at www.micrel.com.
CC
PP
Typical Applications
MIC5219-5.0BMM
1
2
3
4
8
7
6
5
ENABLE
SHUTDOWN
MIC5219-3.3BM5
VIN 6V
VOUT5V
1
2
3
5
VIN 4V
VOUT3.3V
2.2µF
tantalum
4
ENABLE
SHUTDOWN
2.2µF
tantalum
470pF
470pF
5V Ultra-Low-Noise Regulator
3.3V Ultra-Low-Noise Regulator
VOUT
VOUT
COUT
VIN
EN
VIN
EN
MIC5219YMT
MIC5219-x.xYML
+
ENABLE
SHUTDOWN
ENABLE
SHUTDOWN
R1
R2
6
1
6
5
4
1
2
3
CBYP
(optional)
2.2µF
5
4
2
3
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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Micrel, Inc.
MIC5219
Ordering Information
Part Number
Marking
Standard
Pb-Free
Standard
Pb-Free*
—
Volts
2.5V
2.85V
3.0V
3.3V
3.6V
5.0V
Adj.
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
–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
MIC5219-2.5BMM
MIC5219-2.85BMM
MIC5219-3.0BMM
MIC5219-3.3BMM
MIC5219-3.6BMM
MIC5219-5.0BMM
MIC5219BMM
MIC5219-2.5YMM
MIC5219-2.85YMM
MIC5219-3.0YMM
MIC5219-3.3YMM
MIC5219-3.6YMM
MIC5219-5.0YMM
MIC5219YMM
—
—
MSOP-8
MSOP-8
—
—
—
MSOP-8
—
—
MSOP-8
—
—
MSOP-8
—
—
MSOP-8
—
—
MSOP-8
MIC5219-2.5BM5
MIC5219-2.6BM5
MIC5219-2.7BM5
MIC5219-2.8BM5
MIC5219-2.8BML
MIC5219-2.85BM5
MIC5219-2.9BM5
MIC5219-3.1BM5
MIC5219-3.0BM5
MIC5219-3.0BML
MIC5219-3.3BM5
MIC5219-3.3BML
MIC5219-3.6BM5
MIC5219-5.0BM5
MIC5219BM5
MIC5219-2.5YM5
MIC5219-2.6YM5
MIC5219-2.7YM5
MIC5219-2.8YM5
MIC5219-2.8YML
MIC5219-2.85YM5
MIC5219-2.9YM5
MIC5219-3.1YM5
MIC5219-3.0YM5
MIC5219-3.0YML
MIC5219-3.3YM5
MIC5219-3.3YML
MIC5219-3.6YM5
MIC5219-5.0YM5
MIC5219YM5
LG25
LG26
LG27
LG28
G28
LG2J
LG29
LG31
LG30
G30
LG33
G33
LG36
LG50
LGAA
LG25
LG26
LG27
LG28
G28
LG2J
LG29
LG31
LG30
G30
LG33
G33
LG36
LG50
LGAA
GAA
G50
2.5V
2.6V
2.7V
2.8V
2.8V
2.85V
2.9V
3.1V
3.0V
3.0V
3.3V
3.3V
3.6V
5.0V
Adj.
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
6-Pin 2×2 MLF®
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
6-Pin 2×2 MLF®
SOT-23-5
6-Pin 2×2 MLF®
SOT-23-5
SOT-23-5
SOT-23-5
MIC5219YMT
Adj.
–40°C to +125°C 6-Pin 2x2 Thin MLF®**
–40°C to +125°C 6-Pin 2x2 Thin MLF®**
MIC5219-5.0YMT
5.0V
Other voltages available. Consult Micrel for details.
* Over/underbar may not be to scale. ** Pin 1 identifier = ▲.
Pin Configuration
EN
IN
GND
GND
GND
GND
1
2
3
4
8
7
6
5
EN GND IN
3
2
1
6
BYP
EN
GND
IN
1
2
3
LGxx
5
4
NC
OUT
BYP
4
5
OUT
BYP
OUT
®
MIC5219-x.xBML
MIC5219-x.xBM5 / SOT-23-5
Fixed Voltages
MIC5219-x.xBMM / MM8 / MSOP-8
Fixed Voltages
®
6-Pin 2mm × 2mm MLF (ML)
(Top View)
(Top View)
(Top View)
EN
IN
GND
GND
GND
GND
EN GND IN
1
2
3
4
8
7
6
5
3
2
1
6
5
4
NC
Part
EN
GND
IN
1
2
3
Identification
LGAA
OUT
BYP
ADJ
OUT
4
5
ADJ
OUT
MIC5219BM5 / SOT-23-5
Adjustable Voltage
(Top View)
MIC5219YMT
MIC5219YMM / MIC5219BMM
®
®
6-Pin 2mm × 2mm Thin MLF (MT)
MM8 MSOP-8
Adjustable Voltage
(Top View)
(Top View)
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MIC5219
Pin Description
Pin No.
Pin No.
Pin No.
Pin Name
Pin Function
MLF-6
MSOP-8
SOT-23-5
TMLF-6
3
2
4
1
2
5–8
3
1
2
5
3
IN
Supply Input.
GND
OUT
EN
Ground: MSOP-8 pins 5 through 8 are internally connected.
Regulator Output.
1
Enable (Input): CMOS compatible control input. Logic high = enable; logic
low or open = shutdown.
6
4 (fixed)
4 (fixed)
BYP
Reference Bypass: Connect external 470pF capacitor to GND to reduce
output noise. May be left open.
5(NC)
EP
4 (adj.)
—
4 (adj.)
—
ADJ
Adjust (Input): Feedback input. Connect to resistive voltage-divider network.
GND
Ground: Internally connected to the exposed pad. Connect externally to
GND pin.
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MIC5219
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Input Voltage (V )..............................–20V to +20V
Supply Input Voltage (V )............................ +2.5V to +12V
IN
IN
Power Dissipation (P )............................. Internally Limited
Enable Input Voltage (V )....................................0V to V
D
EN
IN
Junction Temperature (T )........................ –40°C to +125°C
Junction Temperature (T )........................ –40°C to +125°C
J
J
Storage Temperature (T ) ........................ –65°C to +150°C
Package Thermal Resistance........................... see Table 1
S
Lead Temperature (Soldering, 5 sec.) ....................... 260°C
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 Typical Max
Units
VOUT
Output Voltage Accuracy
variation from nominal VOUT
–1
–2
1
2
%
%
ΔVOUT/ΔT
ppm/°C
Output Voltage
Note 4
40
Temperature Coefficient
ΔVOUT/VOUT Line Regulation
VIN = VOUT + 1V to 12V
IOUT = 100µA to 500mA, Note 5
IOUT = 100µA
0.009
0.05
10
0.05
0.1
%/V
%
ΔVOUT/VOUT Load Regulation
0.5
0.7
VIN – VOUT
Dropout Voltage(6)
60
80
mV
mV
mV
mV
µA
IOUT = 50mA
115
175
350
80
175
250
IOUT = 150mA
300
400
IOUT = 500mA
500
600
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
350
1.8
650
900
µA
2.5
3.0
mA
mA
12
20
25
Ground Pin Quiescent Current(8)
VEN ≤ 0.4V
0.05
0.10
75
3
µA
µA
dB
mA
VEN ≤ 0.18V
8
PSRR
ILIMIT
Ripple Rejection
Current Limit
f = 120Hz
VOUT = 0V
700
0.05
500
300
1000
ΔVOUT/ΔPD
eno
Thermal Regulation
Output Noise(10)
Note 9
%/W
nV/ Hz
IOUT = 50mA, COUT = 2.2µF, CBYP = 0
IOUT = 50mA, COUT = 2.2µF, CBYP = 470pF
nV/ Hz
ENABLE Input
VENL
Enable Input Logic-Low Voltage
VEN = logic low (regulator shutdown)
0.4
0.18
V
VEN = logic high (regulator enabled)
VENL ≤ 0.4V
2.0
2
V
IENL
IENH
Enable Input Current
0.01
0.01
5
–1
µA
µA
µA
VENL ≤ 0.18V
–2
VENH ≥ 2.0V
20
25
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MIC5219
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, T (max),
J
the junction-to-ambient thermal resistance, θ , and the ambient temperature, T . The maximum allowable power dissipation at any ambient
JA
A
temperature is calculated using: P (max) = (T (max) – T ) ÷ θ . Exceeding the maximum allowable power dissipation will result in excessive die
D
J
A
JA
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. Specification for packaged product only.
4. Output voltage temperature coefficient is defined 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 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.
V
is the voltage externally applied to devices with the EN (enable) input pin.
EN
9. 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 regu-
lation effects. Specifications are for a 500mA load pulse at V = 12V for t = 10ms.
IN
10. C
is an optional, external bypass capacitor connected to devices with a BYP (bypass) or ADJ (adjust) pin.
BYP
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MIC5219
Typical Characteristics
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
0
0
-20
0
-20
VIN = 6V
VOUT = 5V
VIN = 6V
VOUT = 5V
VIN = 6V
VOUT = 5V
-20
-40
-60
-40
-40
-60
-60
IOUT = 100mA
C OUT = 1µF
-80
-80
-80
IOUT = 100µA
C OUT = 1µF
IOUT = 1mA
C OUT = 1µF
-100
-100
-100
1k
1k
1k
10k
1M 10M
10k
1M 10M
10k
1M 10M
100k
10 100
100k
10 100
100k
10 100
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 E+7
FREQUENCY (Hz)
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 E+7
FREQUENCY (Hz)
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 E+7
FREQUENCY (Hz)
Power Supply
Power Supply
Power Supply Ripple Rejection
Rejection Ratio
Rejection Ratio
vs. Voltage Drop
0
0
60
VIN = 6V
VIN = 6V
50
VOUT = 5V
VOUT = 5V
-20
-20
1mA
40
-40
-60
-40
-60
30
20
10
0
10mA
IOUT = 100mA
IOUT = 1mA
C OUT = 2.2µF
C BYP = 0.01µF
IOUT = 100µA
C OUT = 2.2µF
C BYP = 0.01µF
-80
-80
C OUT = 1µF
0.3 0.4
-100
-100
1k
1k
10k
1M 10M
10k
1M 10M
100k
10 100
100k
10 100
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 E+7
FREQUENCY (Hz)
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 E+7
FREQUENCY (Hz)
0
0.1
0.2
VOLTAGE DROP (V)
Power Supply Ripple Rejection
vs. Voltage Drop
Noise Performance
10
Noise Performance
100
10
1
90
80
70
60
50
40
30
20
10
0
10mA, C
= 1µF
OUT
1
0.1
1mA
100mA
10mA
0.1
IOUT = 100mA
10mA
0.01
0.01
0.001
0.0001
VOUT = 5V
1mA
C OUT = 2.2µF
C BYP = 0.01µF
0.001
0.0001
C OUT = 10µF
electrolytic
VOUT = 5V
10
1E+1 1E+2 1E1+k3 1E+4 1E+5 1E+6 1E+7
100 10k 100k 1M 10M
1k
0
0.1
0.2
0.3
0.4
10
10k 100k 1M 10M
1E+1 11E0+02 1E+3 1E+4 E+5 1E+6 1E+7
FREQUENCY (Hz)
VOLTAGE DROP (V)
FREQUENCY (Hz)
Dropout Voltage
vs. Output Current
Dropout Characteristics
Noise Performance
10
1
400
300
200
100
0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
I
=100µA
L
100mA
0.1
I =100mA
0.01
0.001
0.0001
1mA
L
VOUT = 5V
C OUT = 10µF
electrolytic
C BYP = 100pF
I =500mA
L
10mA
0
100 200 300 400 500
OUTPUT CURRENT (mA)
0
1
2
3
4
5
6
7
8
9
1k
10
10k 100k 1M 10M
1E+1 11E0+02 1E+3 1E+4 E+5 1E+6 1E+7
FREQUENCY (Hz)
INPUT VOLTAGE (V)
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MIC5219
Ground Current
vs. Output Current
Ground Current
vs. Supply Voltage
Ground Current
vs. Supply Voltage
12
10
8
25
20
15
10
5
3.0
2.5
2.0
1.5
1.0
0.5
0
6
I =100 mA
L
4
2
I =100µA
I =500mA
L
L
0
0
0
100 200 300 400 500
OUTPUT CURRENT (mA)
0
1
2
3
4
5
6
7
8
9
0
2
4
6
8
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
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MIC5219
Block Diagrams
OUT
IN
VOUT
COUT
VIN
BYP
CBYP
(optional)
Bandgap
Ref.
EN
Current Limit
Thermal Shutdown
MIC5219-x.xBM5/M/YMT
GND
Ultra-Low-Noise Fixed Regulator
OUT
R1
IN
VOUT
COUT
VIN
R2
CBYP
(optional)
Bandgap
Ref.
EN
Current Limit
Thermal Shutdown
MIC5219BM5/MM/YMT
GND
Ultra-Low-Noise Adjustable Regulator
June 2009
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MIC5219
Thermal Considerations
Applications Information
The MIC5219 is designed to provide 200mA of continuous
current in two very small profile packages. Maximum power
dissipationcanbecalculatedbasedontheoutputcurrentand
the voltage drop across the part. To determine the maximum
powerdissipationofthepackage,usethethermalresistance,
junction-to-ambient, of the device and the following basic
equation.
TheMIC5219isdesignedfor150mAto200mAoutputcurrent
applicationswhereahighcurrentspike(500mA)isneededfor
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.
TJ (max ) − TA
(
)
PD (max ) =
θJA
T (max) is the maximum junction temperature of the die,
Input Capacitor
J
125°C, and T is the ambient operating temperature. θ
A
JA
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.
is layout dependent; Table 1 shows examples of thermal
resistance, junction-to-ambient, for the MIC5219.
Package
θ
JA Recommended
Minimum Footprint 2oz. Copper
θJA 1" Squareꢀ θJC
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
MM8® (MM)
160°C/W
220°C/W
90°C/W
70°C/W
170°C/W
—
30°C/W
130°C/W
—
SOT-23-5 (M5)
2×2 MLF® (ML)
used. 1µF minimum is recommended when C
is not used
BYP
2×2 Thin
(see Figure 5). 2.2µF minimum is recommended when C
BYP
MLF® (MT)
90°C/W
—
—
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 in-
creased without limit.
Table 1. MIC5219 Thermal Resistance
The actual power dissipation of the regulator circuit can be
determined using one simple equation.
P = (V – V
) I
+ V I
IN GND
D
IN
OUT OUT
The output capacitor should have an ESR (equivalent series
resistance) of about 1Ω or less and a resonant frequency
above 1MHz. Ultra-low-ESR capacitors could cause oscilla-
tion and/or underdamped transient response. Most tantalum
or aluminum electrolytic capacitors are adequate; film types
will work, but are more expensive. Many aluminum electro-
lytics have electrolytes that freeze at about –30°C, so solid
tantalums are recommended for operation below –25°C.
Substituting P (max) for P and solving for the operating
D
D
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 deter-
mine the maximum input voltage for a set output current.
125 °C − 25°C
(
)
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.
PD(max ) =
220°C / W
P (max) = 455mW
D
No-Load Stability
Thethermalresistance,junction-to-ambient,fortheminimum
footprintis220°C/W,takenfromTable1.Themaximumpower
dissipation number cannot be exceeded for proper opera-
tion 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 Charac-
teristics” section of the data sheet.
TheMIC5219willremainstableandinregulationwithnoload
(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 (C
) connected from BYP to GND quiets this
BYP
455mW = (V – 3.3V) × 150mA + V × 3mA
455mW = (150mA) × V + 3mA × V – 495mW
950mW = 153mA × V
reference, providing a significant reduction in output noise
(ultra-low-noise performance). C reduces the regulator
IN
IN
BYP
IN
IN
phase margin; when using C , output capacitors of 2.2µF
BYP
IN
or greater are generally required to maintain stability.
V
= 6.2V
MAX
IN
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
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 Ther-
mals”sectionofMicrel’sDesigningwithLow-DropoutVoltage
Regulators handbook.
larger values of C . Likewise, if rapid turn-on is necessary,
BYP
consider omitting C
.
BYP
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
Peak Current Applications
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” .)
TheMIC5219isdesignedforapplicationswherehighstart-up
currents are demanded from space constrained regulators.
This device will deliver 500mA start-up current from a SOT-
23-5 or MM8 package, allowing high power from a very low
profiledevice.TheMIC5219cansubsequentlyprovideoutput
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.
Theinformationusedtodeterminethesafeoperatingregions
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
first step, this is done in the same manner as in the previous
two sections. Then, a larger power dissipation number multi-
plied 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 specific example, it may be easier to follow.
TheMIC5219canbeusedtoprovideupto500mAcontinuous
output current. First, calculate the maximum power dissipa-
tion of the device, as was done in the thermal considerations
section. Worst case thermal resistance (θ = 220°C/W for
the MIC5219-x.xBM5), will be used for this example.
JA
TJ (max ) − TA
(
)
PD (max ) =
θJA
Assuming a 25°C room temperature, we have a maximum
power dissipation number of
125 °C − 25°C
(
)
% DC
ꢀ 100 ꢀ
ꢀ
ꢀ
PD (max ) =
Avg.P = ꢀ
ꢀ V – V
I
+ V I
IN GND
(
)
D
IN
OUT
OUT
220 °C /W
P (max) = 455mW
D
% DC
ꢀ
ꢀ
ꢀ
455mW = ꢀ
ꢀ 100 ꢀ
(
8V – 5V 500mA + 8V × 20mA
)
Then we can determine the maximum input voltage for a
5-voltregulatoroperatingat500mA, usingworstcaseground
current.
% Duty Cycle
ꢀ
455mW = ꢀ
ꢀ 100
ꢀ
ꢀ1.66W
ꢀ
P (max) = 455mW = (V – V
) I
+ V I
IN GND
D
IN
OUT OUT
% Duty Cycle
100
I
= 500mA
= 5V
OUT
0.274 =
V
I
OUT
% Duty Cycle Max = 27.4%
= 20mA
GND
455mW = (V – 5V) 500mA + V × 20mA
With an output current of 500mAand a three-volt drop across
the MIC5219-xxBMM, the maximum duty cycle is 27.4%.
IN
IN
2.995W = 520mA × V
IN
Applications also call for a set nominal current output with a
greateramountofcurrentneededforshortdurations.Thisisa
trickysituation,butitiseasilyremedied.Calculatetheaverage
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
520mA
VIN(max ) =
= 5.683V
Therefore, to be able to obtain a constant 500mAoutput cur-
rent 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 en-
able pin can increase the power dissipation of the device by
maintaining a lower average power figure. This is ideal for
applicationswherehighcurrentisonlyneededinshortbursts.
Figure1showsthesafeoperatingregionsfortheMIC5219-x.
xBM5 at three different ambient temperatures and at differ-
ent output currents. The data used to determine this figure
assumed a minimum footprint PCB design for minimum heat
sinking. Figure 2 incorporates the same factors as the first
figure, but assumes a much better heat sink.A1" square cop-
per trace on the PC board reduces the thermal resistance of
thedevice.Thisimprovedthermalresistanceimprovespower
dissipation and allows for a larger safe operating region.
P × 50mA = (5V – 3.3V) × 50mA + 5V × 650µA
D
P × 50mA = 173mW
D
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, P must be mul-
D
tiplied by the duty cycle to obtain the actual average power
dissipation at 50mA.
Figures3and4showsafeoperatingregionsfortheMIC5219-x.
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
10
8
10
8
10
8
100mA
100mA
100mA
200mA
6
6
6
200mA
200mA
300mA
4
4
4
300mA
300mA
60
400mA
2
0
2
2
500mA
400mA
400mA
20
500mA
40
500mA
40
DUTY CYCLE (%)
0
0
0
0
0
0
20
60
80
100
0
60
80
100
0
20
40
80
100
DUTY CYCLE (%)
DUTY CYCLE (%)
a. 25°C Ambient
b. 50°C Ambient
c. 85°C Ambient
Figure 1. MIC5219-x.xBM5 (SOT-23-5) on Minimum Recommended Footprint
10
8
10
8
10
8
100mA
100mA
100mA
200mA
6
200mA
6
6
200mA
300mA
4
4
4
300mA
80
400mA
20
300mA
2
2
2
400mA
20
400mA
500mA
20 40
500mA
40 60
500mA
40 60
DUTY CYCLE (%)
0
0
0
80
100
0
100
0
60
DUTY CYCLE (%)
80
100
DUTY CYCLE (%)
a. 25°C Ambient
b. 50°C Ambient
c. 85°C Ambient
2
Figure 2. MIC5219-x.xBM5 (SOT-23-5) on 1-inch Copper Cladding
10
8
10
8
10
8
100mA
300mA
100mA
100mA
200mA
6
6
6
200mA
200mA
300mA
300mA
4
4
4
400mA
20
400mA
20
2
2
2
400mA
500mA
500mA
40
500mA
20 40
DUTY CYCLE (%)
0
0
0
40
60
80
100
0
60
80
100
0
60
80
100
DUTY CYCLE (%)
DUTY CYCLE (%)
a. 25°C Ambient
b. 50°C Ambient
c. 85°C Ambient
Figure 3. MIC5219-x.xBMM (MSOP-8) on Minimum Recommended Footprint
10
8
10
8
10
8
200mA
300mA
100mA
300mA
200mA
300mA
200mA
6
6
6
400mA
400mA
4
4
4
400mA
20
500mA
500mA
2
2
2
500mA
40
0
0
0
20
40
60
80
100
0
20
40
60
80
100
0
60
80
100
DUTY CYCLE (%)
DUTY CYCLE (%)
DUTY CYCLE (%)
a. 25°C Ambient
b. 50°C Ambient
c. 85°C Ambient
2
Figure 4. MIC5219-x.xBMM (MSOP-8) on 1-inch Copper Cladding
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
P × 50mA = 0.875 × 173mW
MIC5219-x.x
D
VIN
VOUT
P × 50mA = 151mW
IN
OUT
BYP
GND
D
The power dissipation at 500mA must also be calculated.
EN
2.2µF
P × 500mA = (5V – 3.3V) 500mA + 5V × 20mA
D
470pF
P × 500mA = 950mW
D
This number must be multiplied by the duty cycle at which it
would be operating, 12.5%.
Figure 6. Ultra-Low-Noise Fixed Voltage Regulator
P × = 0.125 × 950mW
D
Figure 6 includes the optional 470pF noise bypass capacitor
between BYP and GND to reduce output noise. Note that the
P × = 119mW
D
minimum value of C
capacitor is used.
must be increased when the bypass
The total power dissipation of the device under these condi-
tions is the sum of the two power dissipation figures.
OUT
Adjustable Regulator Circuits
P
P
P
= P × 50mA + P × 500mA
D D
= 151mW + 119mW
= 270mW
D(total)
D(total)
D(total)
MIC5219
VIN
VOUT
1µF
IN
OUT
ADJ
R1
R2
EN
The total power dissipation of the regulator is less than the
maximumpowerdissipationoftheSOT-23-5packageatroom
temperature, on a minimum footprint board and therefore
would operate properly.
GND
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.Theoutputvoltageisconfiguredbyselectingvalues
for R1 and R2 using the following formula:
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
“RegulatorThermals” section of Micrel’s Designing with Low-
Dropout Voltage Regulators handbook.
R2
ꢀ
ꢀR1
ꢀ
ꢀ
V
= 1.242V ꢀ + 1ꢀ
OUT
AlthoughADJisahigh-impedanceinput,forbestperformance,
R2 should not exceed 470kΩ.
MIC5219
Fixed Regulator Circuits
MIC5219-x.x
VIN
VOUT
1µF
VIN
VOUT
IN
OUT
BYP
IN
OUT
ADJ
R1
R2
EN
EN
GND
GND
2.2µF
470pF
Figure 5. Low-Noise Fixed Voltage Regulator
Figure 8. Ultra-Low-Noise Adjustable Application
Figure5showsabasicMIC5219-x.xBMXfixed-voltageregu-
lator circuit. A 1µF minimum output capacitor is required for
basic fixed-voltage applications.
Figure 8 includes the optional 470pF bypass capacitor from
ADJ to GND to reduce output noise.
June 2009
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M0371-061809
Micrel, Inc.
MIC5219
Package Information
8-Pin MSOP (MM)
SOT-23-5 (M5)
June 2009
13
M0371-061809
Micrel, Inc.
MIC5219
®
6-Pin MLF (ML)
®
6-Pin Thin MLF (MT)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
t e l + 1 (408) 944-0800 f a x + 1 (408) 474-1000 w e b 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 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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