MICREL MIC5247

MIC5247
Micrel
MIC5247
150mA Low-Voltage µCap Linear Regulator
Preliminary Information
General Description
Features
The MIC5247 is an efficient, precise low voltage CMOS
voltage regulator optimized for ultra-low-noise applications.
The MIC5247 offers better than 1% initial accuracy, and 85µA
constant ground current over load (typically 85µA). The
MIC5247 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 MIC5247 provides a logic compatible enable pin.
When disabled, power consumption drops nearly to zero.
The MIC5247 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
package, the MIC5247 also offers a range of fixed output
voltages.
Ultralow noise
Low voltage outputs
Load independent, ultralow ground current: 85µA
150mA output current
Current limiting
Thermal Shutdown
Tight load and line regulation
“Zero” off-mode current
Stability with low-ESR capacitors
Fast transient response
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
MIC5247-1.5BM5
LU15
1.5V
–40°C to +125°C
SOT-23-5
MIC5247-1.8BM5
LU18
1.8V
–40°C to +125°C
SOT-23-5
MIC5247-2.0BM5
LU20
2.0V
–40°C to +125°C
SOT-23-5
MIC5247-2.4BM5
LU24
2.4V
–40°C to +125°C
SOT-23-5
Other voltages available. Contact Micrel for details.
Typical Application
VIN MIC5247-x.xBM5
1
5
2
COUT
3
Enable
Shutdown
VOUT
4
EN
CBYP
(optional)
EN (pin 3) may be
connected directly
to IN (pin 1).
Ultra-Low-Noise Regulator Application
IttyBitty is a trademark of Micrel, Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
November 6, 2000
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MIC5247
MIC5247
Micrel
Pin Configuration
EN GND IN
3
2
1
LUxx
4
5
BYP
OUT
MIC5247-x.xBM5
Pin Description
Pin Number
Pin Name
Pin Function
1
IN
Supply Input
2
GND
3
EN
Enable/Shutdown (Input): CMOS compatible input. Logic high = enable;
logic low = shutdown. Do not leave open.
4
BYP
Reference Bypass: Connect external 0.01pF capacitor to GND to reduce
output noise. May be left open.
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 VIN
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 (θJA)...................................... 235°C/W
MIC5247
2
November 6, 2000
MIC5247
Micrel
Electrical Characteristics
VIN = VOUT + 1.0V; VIN = VEN; IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.
Symbol
Parameter
Conditions
Min
Typical
Max
Units
VO
Output Voltage Accuracy
IOUT = 0mA
–1
–2
1
2
%
%
∆VLNR
Line Regulation
VIN = VOUT + 0.1V to 6V
–0.3
+0.3
%/V
∆VLDR
Load Regulation
IOUT = 0.1mA to 150mA, Note 4
2
3
%
Load Regulation for 1.5V only
IOUT = 0.1mA to 150mA, VOUT = 1.5V
3
4
%
VIN – VOUT
Dropout Voltage
IOUT = 150mA (see Note 5)
150
IQ
Quiescent Current
VEN ≤ 0.4V (shutdown)
0.2
1
µA
IGND
Ground Pin Current, Note 6
IOUT = 0mA
85
150
µA
IOUT = 150mA
85
150
µA
50
dB
300
mA
µVrms
PSRR
Power Supply Rejection
f ≤ 1kHz
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
mV
Enable Input
V
1
V
VIL ≤ 0.4V
0.01
µA
VIH ≥ 1.6V
0.01
µA
500
Ω
Thermal Shutdown Temperature
150
°C
Thermal Shutdown Hysteresis
10
°C
Shutdown Resistance Discharge
1.6
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 a1V
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 plus pass transistor base current. The total current drawn from the supply is the sum of
the load current plus the ground pin current.
Note 5.
Note 6.
November 6, 2000
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MIC5247
MIC5247
Micrel
Typical Characteristics
60
60
50
FREQUENCY (Hz)
1x10
1x10-8
CBYP = 0.01µF
VIN = 2.8V
VOUT = 1.8V
COUT = 4.7µF
40
20
ILOAD = 100µA
-10 20 50 80 110 140
TEMPERATURE (°C)
1x101
OUTPUT CURRENT (mA)
60
40
20
ILOAD = 150mA
0
-40
80
60
40
20
ILOAD = 100µA
0
0
-10 20 50 80 110 140
TEMPERATURE (°C)
Dropout Characteristics
VOLTAGE OUT (V)
20
ILOAD = 100µA
ILOAD =
150mA
2
1
ILOAD = 150mA
4
0
0
1
2
3
INPUT VOLTAGE (V)
4
1
2
3
INPUT VOLTAGE (V)
4
Short Circuit Current
vs. Temperature
SHORT CIRCUIT CURRENT (mA)
100
40
= VOUT + 1
100
3
60
IN
Ground Pin Current
80
Ground Pin Current
80
V
FREQUENCY (Hz)
GROUND CURRENT (µA)
60
1
2
3
INPUT VOLTAGE (V)
71
Ground Pin Current
80
0
0
72
70
ILOAD = 50mA
100
0
-40
73
1x103
-7
74
1x102
1x10-6
GROUND CURRENT (µA)
GROUND CURRENT (µA)
PSRR (dB)
CBYP = 0
100
GROUND CURRENT (µA)
1x106
75
1x10-5
Ground Pin Current
MIC5247
Ground Current
vs. Output Current
1x10
1x106
1x104
1x103
1x102
20 IL = 150mA
VIN = 3.4V
10 VOUT = 2.4V
COUT = 10µF Ceramic
0
1x105
CBYP = 0
30
20 IL = 100mA
VIN = 3.4V
10 V
= 2.4V
OUT
COUT = 10µF Ceramic
0
Noise Performance
GROUND CURRENT (µA)
40
1x101
PSRR (dB)
1µF
CBYP = 0
1x10-1
50
30
FREQUENCY (Hz)
1x106
0.01µF
1µF
40
FREQUENCY (Hz)
1x105
60
1x101
Power Supply Rejection Ratio
OUTPUT SPECTRAL NOISE DENSITY (µV/rt Hz)
FREQUENCY (Hz)
1x105
1x101
1x106
1x105
1x102
1x101
1x104
OUT
0
1x104
10
1x104
20
IL = 50mA
20 V = 3.4V
IN
10 VOUT = 2.4V
COUT =10µF Ceramic
0
1x103
30
CBYP = 0
30
1x103
IL = 100µA
VIN = 3.4V
VOUT = 2.4V
C
= 10µF Ceramic
40
1x102
40
50 0.01µF
1x102
PSRR (dB)
60 C
=0
BYP
50
1x103
PSRR (dB)
70
0.01µF
1x106
1µF
1x105
= 0.01µF
1
BYP
1x100
C
1x103
70
80 CBYP = 1µF
1x102
90
Power Supply Rejection Ratio
1x104
Power Supply Rejection Ratio
Power Supply Rejection Ratio
4
500
400
300
200
100
VOUT = 0
0
-40 -10 20 50 80 110 140
TEMPERATURE (°C)
November 6, 2000
MIC5247
Micrel
Turn-On Time
vs. Bypass Capacitance
Output Voltage
vs. Temperature
200
COUT = 10µF
ILOAD = 100mA
150
TIME (µs)
OUTPUT VOLTAGE (V)
2.5
2.4
100
Rise Time
50
Prop Delay
1x101
1x100
1x10-1
1x10-2
-10 20 50 80 110 140
TEMPERATURE (°C)
1x10-3
0
1x10-5
2.3
-40
1x10-4
ILOAD = 100µA
BYPASS CAPACITOR (µF)
November 6, 2000
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MIC5247
MIC5247
Micrel
Functional Characteristics
Line Transient Response
INPUT VOLTAGE
(1V/div.)
OUTPUT VOLTAGE
(100mV/div.)
Load Transient Response
COUT = 10µF
CBYP = 0
VIN = 3.4V
VOUT = 2.4V
3.4V
COUT = 10µF
VOUT = 2.4V
ILOAD = 100µA
OUTPUT VOLTAGE
(50mV/div.)
OUTPUT CURRENT
(100mA/div.)
100mA
100µA
TIME (100µs/div.)
MIC5247
4.4V
TIME (500µs/div.)
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November 6, 2000
MIC5247
Micrel
Block Diagrams
IN
Reference
Voltage
Startup/
Shutdown
Control
Quickstart/
Noise
Cancellation
EN
BYP
PULL
UP
Thermal
Sensor
FAULT
Error
Amplifier
Current
Amplifier
Undervoltage
Lockout
OUT
PULL
DOWN
ACTIVE SHUTDOWN
GND
November 6, 2000
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MIC5247
MIC5247
Micrel
dissipation of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation:
Applications Information
Enable/Shutdown
 TJ(max) − TA 
PD(max) = 

θ JA


The MIC5247 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.
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 MIC5247.
Package
SOT-23-5 (M5)
θJA 1" Square
Copper Clad
θJC
235°C/W
185°C/W
145°C/W
Table 1. SOT-23-5 Thermal Resistance
The actual power dissipation of the regulator circuit can be
determined using the equation:
PD = (VIN – VOUT) IOUT + VIN IGND
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 MIC5247-2.4BM5 at room
temperature with a minimum footprint layout, the maximum
input voltage for a set output current can be determined as
follows:
Output Capacitor
The MIC5247 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 MIC5247 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.
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 bypass capacitor can be increased without bound,
further reducing noise and improving PSRR. Turn-on time
remains constant with respect to bypass capacitance. Refer
to the Typical Characteristics section for a graph of turn-on
time vs. bypass capacitor.
 125°C − 25°C 
PD(max) = 

 235°C/W 
PD(max) = 425mW
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 2.4V and an output current of 150mA,
the maximum input voltage can be determined. Because this
device is CMOS and the ground current is typically 100µA
over the load range, the power dissipation contributed by the
ground current is < 1% and can be ignored for this calculation.
425mW = (VIN – 2.4V) 150mA
425mW = VIN ·150mA – 360mW
Transient Response
The MIC5247 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 (85µA).
785mW = VIN ·150mA
VIN(max) = 5.2V
Therefore, a 2.4V application at 150mA of output current can
accept a maximum input voltage of 5.2V 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.
Fixed Regulator Applications
Active Shutdown
The MIC5247 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.
Thermal Considerations
VIN
MIC5247-x.xBM5
1
5
2
3
The MIC5247 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
MIC5247
θJA Recommended
Minimum Footprint
VOUT
1µF
4
0.01µF
Figure 1. Ultra-Low-Noise Fixed Voltage Application
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November 6, 2000
MIC5247
Micrel
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.
VIN
MIC5247-x.xBM5 V
OUT
1
5
2
3
Enable
Shutdown
1.0µF
4
EN
Figure 2. Low-Noise Fixed Voltage Application
Figure 2 is an example of a low-noise configuration where
CBYP is not required. COUT = 1µF minimum.
November 6, 2000
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MIC5247
MIC5247
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)
1.30 (0.051)
0.90 (0.035)
3.02 (0.119)
2.80 (0.110)
0.20 (0.008)
0.09 (0.004)
10°
0°
0.15 (0.006)
0.00 (0.000)
0.50 (0.020)
0.35 (0.014)
0.60 (0.024)
0.10 (0.004)
SOT-23-5 (M)
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
MIC5247
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November 6, 2000