MICREL MIC5245

MIC5245
Micrel
MIC5245
150mA µCap CMOS LDO Regulator
Preliminary Information
General Description
Features
The MIC5245 is an efficient, precise CMOS voltage regulator
optimized for ultra-low-noise applications. The MIC5245 offers better than 1% initial accuracy, extremely low dropout
voltage (typically 150mV at 150mA) and constant ground
current over load (typically 100µA). The MIC5245 provides a
very low noise output, ideal for RF applications where quiet
voltage sources are required. A noise bypass pin is also
available for further reduction of output noise.
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Designed specifically for hand-held and battery-powered
devices, the MIC5245 provides a TTL logic compatible enable pin. When disabled, power consumption drops nearly to
zero.
The MIC5245 also works with low-ESR ceramic capacitors,
reducing the amount of board space necessary for power
applications, critical in hand-held wireless devices.
Key features include current limit, thermal shutdown, a pushpull output for faster transient response, and an active clamp
to speed up device turnoff. Available in the IttyBitty™ SOT-23-5
and power MSO-8 packages, the MIC5245 also offers a
range of fixed output voltages.
Ultralow dropout—100mV @ 100mA
Ultralow noise—30µV(rms)
Stability with tantalum or ceramic capacitors
Load independent, ultralow ground current
150mA output current
Current limiting
Thermal Shutdown
Tight load and line regulation
“Zero” off-mode current
Fast transient response
TTL-Logic-controlled enable input
Applications
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Cellular phones and pagers
Cellular accessories
Battery-powered equipment
Laptop, notebook, and palmtop computers
PCMCIA VCC and VPP regulation/switching
Consumer/personal electronics
SMPS post-regulator/dc-to-dc modules
High-efficiency linear power supplies
Ordering Information
Part Number
Marking
Voltage
Junction Temp. Range
Package
MIC5245-2.5BM5
LS25
2.5V
–40°C to +125°C
SOT-23-5
MIC5245-2.7BM5
LS27
2.7V
–40°C to +125°C
SOT-23-5
MIC5245-2.8BM5
LS28
2.8V
–40°C to +125°C
SOT-23-5
MIC5245-2.85BM5
LS2J
2.85V
–40°C to +125°C
SOT-23-5
MIC5245-3.0BM5
LS30
3.0V
–40°C to +125°C
SOT-23-5
MIC5245-3.1BM5
LS31
3.1V
–40°C to +125°C
SOT-23-5
MIC5245-3.3BM5
LS33
3.3V
–40°C to +125°C
SOT-23-5
MIC5245-3.3BMM
—
3.3V
–40°C to +125°C
MSOP-8
Other voltages available. Contact Micrel for details.
Typical Application
VIN MIC5245-x.xBM5
1
5
2
3
Enable
Shutdown
EN
EN (pin 3) may be
connected directly
o IN (pin 1).
VOUT
COUT
4
CBYP
(optional)
MIC5245-3.3MM
ENABLE
SHUTDOWN
1
8
VIN
2
7
VOUT
3
6
4
5
COUT
CBYP
(OPTIONAL)
Ultra-Low-Noise Regulator Application
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 2000
1
MIC5245
MIC5245
Micrel
Pin Configuration
EN GND IN
3
2
1
LSxx
4
5
BYP
OUT
MIC5245-x.xBM5
EN 1
8 GND
IN 2
7 GND
OUT 3
6 GND
BYP 4
5 GND
8-Pin MSOP (BMM)
Pin Description
Pin Number
Power MOS-8
Pin Number
SOT-23
Pin Name
Pin Function
2
1
IN
Supply Input
5–8
2
GND
1
3
EN
Enable/Shutdown (Input): CMOS compatible input. Logic high = enable;
logic low = shutdown. Do not leave open.
4
4
BYP
Reference Bypass: Connect external 0.01µF capacitor to GND to reduce
output noise. May be left open.
3
5
OUT
Regulator Output
Ground
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Input Voltage (VIN) .................................. 0V to +7V
Enable Input Voltage (VEN) ................................. 0V to +7V
Junction Temperature (TJ) ...................................... +150°C
Storage Temperature ............................... –65°C to +150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
ESD, Note 3
Input Voltage (VIN) ......................................... +2.7V to +6V
Enable Input Voltage (VEN) .................................. 0V to VIN
Junction Temperature (TJ) ....................... –40°C to +125°C
Thermal Resistance
SOT-23 (θJA) .....................................................235°C/W
MSOP-8 (θJA) ......................................................80°C/W
MIC5245
2
June 2000
MIC5245
Micrel
Electrical Characteristics
VIN = VOUT + 1V, VEN = VIN; IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.
Symbol
Parameter
Conditions
Min
VO
Output Voltage Accuracy
IOUT = 0mA
–1
–2
∆VLNR
Line Regulation
VIN = VOUT + 0.1V to 6V
Max
Units
1
2
%
%
0
0.3
%/V
∆VLDR
Load Regulation
IOUT = 0.1mA to 150mA, Note 4
2.0
3.0
%
VIN – VOUT
Dropout Voltage, Note 5
IOUT = 100µA
1.5
5
mV
IOUT = 50mA
50
85
mV
IOUT = 100mA
100
150
mV
IOUT = 150mA
150
200
250
mV
mV
–0.3
Typical
IQ
Quiescent Current
VEN ≤ 0.4V (shutdown)
0.2
1
µA
IGND
Ground Pin Current, Note 6
IOUT = 0mA
100
150
µA
IOUT = 150mA
100
µA
50
dB
300
mA
µV(rms)
PSRR
Power Supply Rejection
f = 120Hz, COUT = 10µF, CBYP = 0.01µF
ILIM
Current Limit
VOUT = 0V
en
Output Voltage Noise
COUT = 10µF, CBYP = 0.01µF,
f = 10Hz to 100kHz
30
VIL
Enable Input Logic-Low Voltage
VIN = 2.7V to 5.5V, regulator shutdown
0.8
VIH
Enable Input Logic-High Voltage
VIN = 2.7V to 5.5V, regulator enabled
IEN
Enable Input Current
160
Enable Input
V
1
V
VIL ≤ 0.4V
0.17
µA
VIH ≥ 2.0V
1.5
µA
500
Ω
Thermal Shutdown Temperature
150
°C
Thermal Shutdown Hysteresis
10
°C
Shutdown Resistance Discharge
2.0
0.4
Thermal Protection
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
Devices are ESD sensitive. Handling precautions recommended.
Note 4.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load
range from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
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. For outputs below 2.7V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.7V. Minimum
input operating voltage is 2.7V.
Ground pin current is the regulator quiescent current. The total current drawn from the supply is the sum of the load current plus the ground
pin current.
Note 5.
Note 6.
June 2000
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MIC5245
MIC5245
Micrel
Typical Characteristics
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
100
60
40
VIN = 4V
VOUT = 3V
IOUT = 100mA
80 COUT = 1µF tant
PSRR (dB)
IOUT = 10mA
80 COUT = 1µF tant
PSRR (dB)
60
40
VIN = 4V
VOUT = 3V
60
40
20
20
20
0
1E+1
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
0
1E+1
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
0
1E+1
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
100
80
80
60
40
PSRR (dB)
100
VIN = 4V
VOUT = 3V
PSRR (dB)
IOUT = 150mA
80 COUT = 1µF tant
60
40
IOUT = 100µA
COUT = 10µF cer.
CBYP = 0.01µF
0
1E+1
1k 1E+4
10k 1E+5
1M 1E+7
10M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
20 V = 4V
IN
VOUT = 3V
0
1E+1
100 1E+3
1k 1E+4
10k 1E+5
100k 1E+6
1M 1E+7
10M
10 1E+2
FREQUENCY (Hz)
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
100
100
60
40
IOUT = 100mA
COUT = 10µF cer.
CBYP = 0.01µF
20
60
40
IOUT = 150mA
COUT = 10µF cer.
CBYP = 0.01
20
Power Supply Ripple Rejection
vs. Voltage Drop
10mA
30
20
10
0
0
MIC5245
100µA
COUT = 10µF cer.
CBYP = 0.01µF
200 400 600 800 1000
VOLTAGE DROP (mV)
70
100µA
10mA
60
50
40
30
150mA
20
IOUT = 100mA
10
0
0
COUT = 1µF
200 400 600 800 1000
VOLTAGE DROP (mV)
Noise Performance
10
IL = 100µA
IL = 100µA
IOUT = 100mA
NOISE (µV/√Hz)
RIPPLE REJECTION (dB)
100mA
50
40
Power Supply Ripple Rejection
vs. Voltage Drop
10
70
60
0
1E+1
100 1E+3
1k 1E+4
10k 1E+5
100k 1E+6
1M 1E+7
10M
10 1E+2
FREQUENCY (Hz)
Noise Performance
80
IOUT = 10mA
COUT = 10µF cer.
CBYP = 0.01µF
20
0
1E+1
1E+7
100 1E+3
1k 1E+4
10k 1E+5
100k 1E+6
1M 10M
10 1E+2
FREQUENCY (Hz)
0
1E+1
100 1E+3
1k 1E+4
10k 1E+5
100k 1E+6
1M 1E+7
10M
10 1E+2
FREQUENCY (Hz)
40
80
VIN = 4V
VOUT = 3V
80
PSRR (dB)
80
VIN = 4V
VOUT = 3V
VIN = 4V
VOUT = 3V
60
RIPPLE REJECTION (dB)
20
1
VIN = 4V
0.1 V
OUT = 3V
COUT = 1µF cer.
CBYP = 0.01µF
0.01
10 1E+2
100 1E+3
1k 1E+4
10k 100k
1M
1E+1
1E+5 1E+6
FREQUENCY (Hz)
4
NOISE (µV/√Hz)
PSRR (dB)
VIN = 4V
VOUT = 3V
100
PSRR (dB)
100
100
IOUT = 100µA
80 COUT = 1µF tant
PSRR (dB)
Power Supply
Rejection Ratio
1
VIN = 4V
0.1 VOUT = 3V
COUT = 10µF cer.
CBYP = 0.01µF
0.01
1k 1E+4
10 1E+2
1M
10k 1E+5
100 1E+3
100k 1E+6
1E+1
FREQUENCY (Hz)
June 2000
MIC5245
Micrel
Ground Pin Current
Ground Pin Current
200
QUIESCENT CURRENT (µA)
QUIESCENT CURRENT (µA)
95
VIN = 4V
VOUT = 3V
90
85
0.1
1
10
100
LOAD CURRENT (mA)
VOUT = 3V
75
50
25
IOUT = 100µA
50
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
0
Dropout Characteristics
RL = 30Ω
1.0
0.5
1
2
3
4
INPUT VOLTAGE (V)
ILOAD = 100µA
6
4
2
Dropout Voltage
TA = 25°C
100
TA = -40°C
25 50 75 100 125 150
OUTPUT CURRENT (mA)
IOUT = 150mA
1
2
3
4
INPUT VOLTAGE (V)
5
200
150
100
50
Output Voltage
vs. Temperature
3.05
500
400
300
200
IL = 150mA
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
VIN = 3.5V
VEN = 3V
100
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
5
OUTPUT VOLTAGE (V)
TA = 125°C
250
Short Circuit Current
OUTPUT CURRENT (mA)
DROPOUT VOLTAGE (mV)
25
Dropout Voltage
600
250
June 2000
50
300
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
5
300
0
0
75
0
0
5
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
OUTPUT VOLTAGE (V)
RL = 30kΩ
1.5
50
1
2
3
4
INPUT VOLTAGE (V)
VOUT = 3V
Dropout Voltage
VOUT = 3V
2.0
150
0
8
3.5
200
Ground Pin Current
100
QUIESCENT CURRENT (µA)
QUIESCENT CURRENT (µA)
QUIESCENT CURRENT (µA)
VIN = 4V
VOUT = 3V
IOUT = 150mA
0
0
IOUT = 100µA
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Ground Pin Current
75
2.5
50
100
100
3.0
100
500
Ground Pin Current
150
125
150
VIN = 4V
VOUT = 3V
VIN = 4V
TYPICAL 3V DEVICE
3.00
2.95
2.90
ILOAD = 100µA
2.85
-50
0
50
100
TEMPERATURE (°C)
150
MIC5245
MIC5245
Micrel
Enable Pin Bias Current
4
THRESHOLD VOLTAGE (V)
ENABLE PIN CURRENT (µA)
2.0
1.5
VIN = 4.0V
1.0
0.5
VEN = 100mV
Enable Threshold Voltage
3
2
VIN = 4.0V
1
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
Functional Characteristics
Load Transient Response
∆ OUTPUT VOLTAGE
(100mV/div.)
OUTPUT CURRENT
6V
VOUT = 3V
COUT = 10µF
CBYP = 0.01µF
IOUT = 100µA
4V
VIN = 4V
VOUT = 3V
COUT = 10µF cer.
CBYP = 0.01µF
Enable Pin Delay
Shutdown Delay
100µA
OUTPUT VOLTAGE
(1V/div.)
OUTPUT VOLTAGE
(1V/div.)
ENABLE VOLTAGE
(2V/div.)
TIME (100µs/div.)
VIN = 4V
VOUT = 3V
COUT = 10µF
CBYP = 0.01µF
IOUT = no load
TIME (20µs/div.)
MIC5245
150mA
TIME (10ms/div.)
ENABLE VOLTAGE
(1V/div.)
INPUT VOLTAGE
(2V/div.)
∆ OUTPUT VOLTAGE
(50mV/div.)
Line Transient Response
VOUT = 3V
COUT = 10µF
CBYP = 0.01µF
IOUT = no load
TIME (1ms/div.)
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June 2000
MIC5245
Micrel
Block Diagrams
IN
Reference
Voltage
Startup/
Shutdown
Control
Quickstart/
Noise
Cancellation
EN
BYP
PULL
UP
Thermal
Sensor
FAULT
Error
Amplifier
Undervoltage
Lockout
Current
Amplifier
ACTIVE SHUTDOWN
OUT
PULL
DOWN
GND
June 2000
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MIC5245
MIC5245
Micrel
Active Shutdown
The MIC5245 also features an active shutdown clamp, which
is an N-channel MOSFET that turns on when the device is
disabled. This allows the output capacitor and load to discharge, de-energizing the load.
Applications Information
Enable/Shutdown
The MIC5245 comes with an active-high enable pin that
allows the regulator to be disabled. Forcing the enable pin low
disables the regulator and sends it into a “zero” off-modecurrent state. In this state, current consumed by the regulator
goes nearly to zero. Forcing the enable pin high enables the
output voltage. This part is CMOS and the enable pin cannot
be left floating; a floating enable pin may cause an indeterminate state on the output.
Input Capacitor
An input capacitor is not required for stability. A 1µF input
capacitor is recommended when the bulk ac supply capacitance is more than 10 inches away from the device, or when
the supply is a battery.
Thermal Considerations
The MIC5245 is designed to provide 150mA of continuous
current in a very small package. 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 junction-to-ambient thermal resistance of the device and the following basic equation:
 TJ(max) − TA 
PD(max) = 

θ JA


Output Capacitor
The MIC5245 requires an output capacitor for stability. The
design requires 1µF or greater on the output to maintain
stability. The capacitor can be a low-ESR ceramic chip
capacitor. The MIC5245 has been designed to work specifically with the low-cost, small chip capacitors. Tantalum
capacitors can also be used for improved capacitance over
temperature. The value of the capacitor can be increased
without bound.
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 junction-toambient thermal resistance for the MIC5245.
X7R dielectric ceramic capacitors are recommended because of their temperature performance. X7R-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic
capacitors. Z5U and Y5V dielectric capacitors change value
by as much 50% and 60% respectively over their operating
temperature ranges. To use a ceramic chip capacitor with
Y5V dielectric, the value must be much higher than an X7R
ceramic or a tantalum capacitor to ensure the same minimum
capacitance value over the operating temperature range.
Tantalum capacitors have a very stable dielectric (10% over
their operating temperature range) and can also be used with
this device.
Bypass Capacitor
A capacitor can be placed from the noise bypass pin to
ground to reduce output voltage noise. The capacitor bypasses the internal reference. A 0.01µF capacitor is recommended for applications that require low-noise outputs.
The actual power dissipation of the regulator circuit can be
determined using the equation:
PD = (VIN – VOUT) IOUT + VIN IGND
Package
SOT-23-5 (M5)
235°C/W
185°C/W
θJC
145°C/W
Table 1. SOT-23-5 Thermal Resistance
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, when operating the MIC5245-3.3BM5 at 50°C with
a minimum footprint layout, the maximum input voltage for a
set output current can be determined as follows:
 125°C − 50°C 
PD(max) = 

 235°C/W 
PD(max) = 315mW
The junction-to-ambient thermal resistance for the minimum
footprint is 235°C/W, from Table 1. The maximum power
dissipation must not be exceeded for proper operation. Using
the output voltage of 3.3V and an output current of 150mA,
the maximum input voltage can be determined. Because this
device is CMOS and the ground current is typically 87µA over
the load range, the power dissipation contributed by the
ground current is < 1% and can be ignored for this calculation.
315mW = (VIN – 3.3V) 150mA
Transient Response
The MIC5245 implements a unique output stage to dramatically improve transient response recovery time. The output is
a totem-pole configuration with a P-channel MOSFET pass
device and an N-channel MOSFET clamp. The N-channel
clamp is a significantly smaller device that prevents the
output voltage from overshooting when a heavy load is
removed. This feature helps to speed up the transient response by significantly decreasing transient response recovery time during the transition from heavy load (100mA) to light
load (100µA).
MIC5245
θJA Recommended θJA 1" Square
Minimum Footprint Copper Clad
315mW = VIN × 150mA – 495mW
810mW = VIN × 150mA
VIN(max) = 5.4V
Therefore, a 3.3V application at 150mA of output current can
accept a maximum input voltage of 5.4V in a SOT-23-5
package. For a full discussion of heat sinking and thermal
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June 2000
MIC5245
Micrel
effects on voltage regulators, refer to the Regulator Thermals
section of Micrel’s Designing with Low-Dropout Voltage Regulators handbook.
Fixed Regulator Applications
VIN
MIC5245-x.xBM5
1
5
2
3
VIN
1
5
2
3
Enable
Shutdown
1.0µF
4
EN
VOUT
Figure 2. Low-Noise Fixed Voltage Application
1µF
4
Figure 2 is an example of a low-noise configuration where
CBYP is not required. COUT = 1µF minimum.
0.01µF
Dual-Supply Operation
When used in dual supply systems where the regulator load
is returned to a negative supply, the output voltage must be
diode clamped to ground.
Figure 1. Ultra-Low-Noise Fixed Voltage Application
Figure 1 includes a 0.01µF capacitor for low-noise operation
and shows EN (pin 3) connected to IN (pin 1) for an application where enable/shutdown is not required. COUT = 1µF
minimum.
June 2000
MIC5245-x.xBM5 V
OUT
9
MIC5245
MIC5245
Micrel
Package Information
1.90 (0.075) REF
0.95 (0.037) REF
1.75 (0.069)
1.50 (0.059)
3.00 (0.118)
2.60 (0.102)
DIMENSIONS:
MM (INCH)
3.02 (0.119)
2.80 (0.110)
0.50 (0.020)
0.35 (0.014)
1.30 (0.051)
0.90 (0.035)
0.20 (0.008)
0.09 (0.004)
10°
0°
0.15 (0.006)
0.00 (0.000)
0.60 (0.024)
0.10 (0.004)
SOT-23-5 (M)
MIC5245
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June 2000
MIC5245
June 2000
Micrel
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MIC5245
MIC5245
Micrel
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
USA
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 2000 Micrel Incorporated
MIC5245
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June 2000