MICREL MIC5256

MIC5256
Micrel
MIC5256
150mA µCap LDO with Error Flag
Final Information
General Description
Features
The MIC5256 is an efficient, precise CMOS voltage regulator. It offers better than 1% initial accuracy, extremely lowdropout voltage (typically 135mV at 150mA) and low ground
current (typically 90µA) over load. The MIC5256 features an
error flag that indicates an output fault condition such as
overcurrent, thermal shutdown and dropout.
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Designed specifically for handheld and battery-powered devices, the MIC5256 provides a TTL-logic-compatible enable
pin. When disabled, power consumption drops nearly to zero.
The MIC5256 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, faster
transient response, and an active clamp to speed up device
turnoff. Available in the IttyBitty™ SOT-23-5 package and the
new Thin SOT-23-5, which offers the same footprint as the
standard IttyBitty™ SOT-23-5, but only 1mm tall. The MIC5256
offers a range of output voltages.
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Input voltage range: 2.7V to 6.0V
Thin SOT package: 1mm height
Error flag indicates fault condition
Stable with ceramic output capacitor
Ultralow dropout: 135mV @ 150mA
High output accuracy:
1.0% initial accuracy
2.0% over temperature
Low quiescent current: 90µA
Tight load and line regulation
Thermal shutdown and current limit protection
“Zero” off-mode current
TTL logic-controlled enable input
Applications
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•
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Cellular phones and pagers
Cellular accesories
Battery-powered equipment
Laptop, notebook, and palmtop computers
Consumer/personal electronics
Ordering Information
Part Number
Marking
Voltage
Junction Temp. Range
Package
MIC5256-2.6BM5
LX26
2.6V
–40°C to +125°C
SOT-23-5
MIC5256-2.7BM5
LX27
2.7V
–40°C to +125°C
SOT-23-5
MIC5256-2.8BM5
LX28
2.8V
–40°C to +125°C
SOT-23-5
MIC5256-2.85BM5
LX2J
2.85V
–40°C to +125°C
SOT-23-5
MIC5256-3.0BM5
LX30
3.0V
–40°C to +125°C
SOT-23-5
MIC5256-3.3BM5
LX33
3.3V
–40°C to +125°C
SOT-23-5
MIC5256-2.85BD5
NX2J
2.85V
–40°C to +125°C
TSOT-23-5
Other voltages available. Contact Micrel for details.
Typical Application
CIN = 1.0µF
Ceramic
VIN
MIC5256-x.xBM5
1
5
2
3
Enable
Shutdown
4
VOUT
COUT = 1.0µF
Ceramic
FLG
EN
EN (pin 3) may be
connected directly
to IN (pin 1).
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
June 2003
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MIC5256
MIC5256
Micrel
Pin Configuration
EN GND IN
3
2
EN GND IN
1
3
LXxx
2
1
NWxx
4
5
4
5
FLG
OUT
BYP
OUT
MIC5256-x.xBM5
(SOT-23-5)
MIC5256-x.xBD5
(TSOT-23-5)
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
FLG
Error Flag (Output): Open-drain output. Active low indicates an output
undervoltage condition.
5
OUT
Regulator Output.
MIC5256
Ground.
2
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MIC5256
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Input Voltage (VIN) .................................. 0V to +7V
Enable Input Voltage (VEN) ................................. 0V to +7V
Power Dissipation (PD) ............... Internally Limited, Note 3
Junction Temperature (TJ) ....................... –40°C to +125°C
Storage Temperature ............................... –65°C to +150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
ESD, Note 4 .................................................................. 2kV
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
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 = 100µA
∆VLNR
Line Regulation
VIN = VOUT + 1V to 6V
∆VLDR
Load Regulation
VIN – VOUT
Dropout Voltage, Note 6
Typical
Max
Units
+1
+2
%
%
0.02
0.05
%/V
IOUT = 0.1mA to 150mA, Note 5
1.5
2.5
%
IOUT = 100µA
0.1
5.0
mV
IOUT = 100mA
90
150
mV
IOUT = 150mA
135
200
250
mV
mV
–1
–2
IQ
Quiescent Current
VEN ≤ 0.4V (shutdown)
0.2
1
µA
IGND
Ground Pin Current, Note 7
IOUT = 0mA
90
150
µA
IOUT = 150mA
117
µA
f = 10Hz, VIN = VOUT + 1V; COUT = 1µF
60
dB
f = 100Hz, VIN = VOUT + 0.5V; COUT = 1µF
60
dB
f = 10kHz, VIN = VOUT + 0.5V
45
dB
425
mA
tbd
µV(rms)
PSRR
Power Supply Rejection
ILIM
Current Limit
en
Output Voltage Noise
VOUT = 0V
160
Enable Input
VIL
Enable Input Logic-Low Voltage
VIN = 2.7V to 5.5V, regulator shutdown
0.4
VIH
Enable Input Logic-High Voltage
VIN = 2.7V to 5.5V, regulator enabled
IEN
Enable Input Current
VIL ≤ 0.4V, regulator shutdown
0.01
µA
VIH ≥ 1.6V, regulator enabled
0.01
µA
500
Ω
1.6
Shutdown Resistance Discharge
V
V
Error Flag
VFLG
Low Threshold
High Threshold
% of VOUT (Flag ON)
% of VOUT (Flag OFF)
90
96
%
%
VOL
Output Logic-Low Voltage
IL = 100µA, fault condition
0.02
0.1
V
IFL
Flag Leakage Current
flag off, VFLG = 6V
0.01
µA
Thermal Shutdown Temperature
150
°C
Thermal Shutdown Hysteresis
10
°C
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.
The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = TJ(max)–TA/θJA. Exceeding the maximum allowable
June 2003
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MIC5256
MIC5256
Micrel
power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The θJA of the MIC5255-x.xBM5 (all
versions) is 235°C/W on a PC board (see “Thermal Considerations” section for further details).
Note 4.
Devices are ESD sensitive. Handling precautions recommended.
Note 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 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 6.
Note 7.
MIC5256
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MIC5256
Micrel
Typical Characteristics
Power Supply Rejection Ratio
70
60
60
60
50
50
Ground Pin Current
110
VIN = VOUT + 1V
1000000
100000
10000
113
111
109
107
105
103
101
99
97
Ground Pin Current
Ground Pin Current
ILOAD = 100µA
120
115
110
105
100
I
= 150mA
LOAD
95
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
Ground Pin Current
Dropout Characteristics
80
60
40
I
LOAD
= 100µA
3.5
120
OUTPUT VOLTAGE (V)
100
GROUND CURRENT (µA)
140
120
100
80
60
40
20
I
LOAD
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
INPUT VOLTAGE (V)
= 150mA
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
INPUT VOLTAGE (V)
Dropout Voltage
3 ILOAD = 100µA
2.5
0.5
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
INPUT VOLTAGE (V)
Dropout Voltage
160
160
0.06
0.04
0.02
ILOAD = 100µA
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
June 2003
100
80
60
40
20
ILOAD = 150mA
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
5
DROPOUT VOLTAGE (mV)
0.12
DROPOUT VOLTAGE (mV)
180
0.08
= 150mA
1
Dropout Voltage
120
LOAD
1.5
180
140
I
2
0.14
0.1
COUT = 1µF
200 400 600 800 1000
VOLTAGE DROP (mV)
125
95
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
1
10
100
1000
OUTPUT CURRENT (mA)
140
GROUND CURRENT (µA)
0
0
GROUND CURRENT (µA)
115
20
10
Ground Pin Current
GROUND CURRENT (µA)
GROUND CURRENT (µA)
120
ILOAD = 150mA
30
20
150mA*
*ILOAD
COUT = 4.7µF Ceramic
115
125
40
FREQUENCY (Hz)
130
100
0.1
100mA*
10
1000000
0
FREQUENCY (Hz)
105
PSRR (dB)
50mA*
30
10
100000
10000
1000
10
100
*ILOAD
10 C
OUT = 1.0µF Ceramic
0
40
20
ILOAD = 100µA
50
100µA*
1000
30
100µA*
50mA*
100mA*
150mA*
100
40
20
DROPOUT VOLTAGE (mV)
PSRR vs. Voltage Drop
70
PSRR (dB)
PSRR (dB)
Power Supply Rejection Ratio
70
T = –40C
140
120
100
80
60
T = 25C
T = 125C
40
20
0
0
20 40 60 80 100 120 140 160
OUTPUT CURRENT (mA)
MIC5256
MIC5256
Micrel
400
300
200
100
3.5
4
4.5
5
5.5
INPUT VOLTAGE (V)
6
500
490
3.05
VIN = VOUT + 1V
3.04
OUTPUT VOLTAGE (V)
SHORT CIRCUIT CURRENT (mA)
500
480
470
460
450
440
430
420
410
Enable Threshold
vs. Temperature
3.01
3.00
2.99
2.98
2.97
2.96
Error Flag Pull-Up Resistor
1.3
4.5
1.25
4
1.2
1.15
1.1
1.05
1
0.95
0.9
0.85
3.03
3.02
ILOAD = 100µA
2.95
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
400
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
FLAG VOLTAGE (V)
0
3
Output Voltage vs.
Temperature
Short Circuit Current
600
ENABLE THRESHOLD VOLTAGE (V)
SHORT CIRCUIT CURRENT (mA)
Short Circuit Current
Power Good
3.5
3
2.5
2
VIN = 4V
1.5
1
0.5
ILOAD = 100µA
0.8
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
0
0.1
1
Power Fail
10
100 1000 10000
RESISTANCE (kΩ)
Test Circuits
MIC5256
1.0µF*
Ceramic
0V
47k
ON
OFF
0.01µF
1.0µF*
Ceramic
Error Flag Output
* CIN = COUT = 1µF
Figure 1. Test Circuit
MIC5256
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June 2003
MIC5256
Micrel
Functional Characteristics
Line Transient Response
CIN = 1µF Ceramic
COUT = 1µF Ceramic
IOUT = 100µA
Input Voltage
(1V/div)
Output Voltage
(50mV/div)
Load Transient Response
Output Voltage
(50mV/div)
150mA
100µA
TIME (4µs/div)
TIME (400µs/div)
Enable Pin Delay
Shutdown Delay
CIN = 1µF Ceramic
COUT = 1µF Ceramic
IL = 100µA
Enable Voltage
(1V/div)
Enable Voltage
(1V/div)
Output Current
(100mA/div)
CIN = 1µF Ceramic
COUT = 1µF Ceramic
VIN = 4V
Output Voltage
(1V/div)
Output Voltage
(1V/div)
CIN = 1µF Ceramic
COUT = 1µF Ceramic
IOUT = 100µA
Error Flag Start-up*
Error Flag Shutdown*
Output Voltage
(2V/div)
Error Flag
(2V/div)
Error Flag
(2V/div)
Output Voltage
(2V/div)
Enable Voltage
(2V/div)
TIME (400µs/div)
Enable Voltage
(2V/div)
TIME (10µs/div)
TIME (400µs/div)
TIME (400µs/div)
* See Test Circuit Figure 1
June 2003
* See Test Circuit Figure 1
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MIC5256
MIC5256
Micrel
Block Diagram
IN
EN
Reference
Voltage
Thermal
Sensor
Startup/
Shutdown
Control
Quickstart
FAULT
Error
Amplifier
Undervoltage
Lockout
Current
Amplifier
OUT
ACTIVE SHUTDOWN
Out of
Regulation
Detection
FLG
Overcurrent
Dropout
Detection
GND
MIC5256
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June 2003
MIC5256
Micrel
the input without using a pull-down capacitor, then there can
be a glitch on the error flag upon start up of the device. This
is due to the response time of the error flag circuit as the
device starts up. When the device comes out of the “zero” off
mode current state, all the various nodes of the circuit power
up before the device begins supplying full current to the
output capacitor. The error flag drives low immediately and
then releases after a few microseconds. The intelligent circuit
that triggers an error detects the output going into current limit
AND the output being low while charging the output capacitor.
The error output then pulls low for the duration of the turn-on
time. A capacitor from the error flag to ground will filter out this
glitch. The glitch does not occur if the error flag pulled up to
the output.
Active Shutdown
Applications Information
Enable/Shutdown
The MIC5256 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
The MIC5256 is a high performance, high bandwidth device.
Therefore, it requires a well-bypassed input supply for optimal performance. A 1µF capacitor is required from the input
to ground to provide stability. Low ESR ceramic capacitors
provide optimal performance at a minimum of space. Additional high-frequency capacitors, such as small valued NPO
dielectric type capacitors, help filter out high frequency noise
and are good practice in any RF based circuit.
The MIC5256 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.
No Load Stability
The MIC5256 will remain stable and in regulation with no load
unlike many other voltage regulators. This is especially
important in CMOS RAM keep-alive applications.
Output capacitor
The MIC5256 requires an output capacitor for stability. The
design requires 1µF or greater on the output to maintain
stability. The design is optimized for use with low ESR
ceramic chip capacitors. High ESR capacitors may cause
high frequency oscillation. The maximum recommended
ESR is 300mΩ. The output capacitor can be increased, but
performance has been optimized for a 1µF ceramic output
capacitor and does not improve significantly with larger
capacitance.
Thermal Considerations
The MIC5256 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:
X7R/X5R dielectric-type ceramic capacitors are recommended because of their temperature performance. X7Rtype 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 as 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 capacitor to ensure the same minimum capacitance over the equivalent operating temperature range.
Error Flag
The error flag output is an active-low, open-drain output that
drives low when a fault condition AND an undervoltage
detection occurs. Internal circuitry intelligently monitors
overcurrent, overtemperature and dropout conditions and
ORs these outputs together to indicate some fault condition.
The output of that OR gate is ANDed with an output voltage
monitor that detects an undervoltage condition. That output
drives the open-drain transistor to indicate a fault. This
prevents chattering or inadvertent triggering of the error flag.
The error flag must be pulled-up using a resistor from the flag
pin to either the input or the output.
 TJ(max) − TA 
PD(max) = 

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 junction-toambient thermal resistance for the MIC5256.
Package
SOT-23-5
(M5 or D5)
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 MIC5256-3.0BM5 at 50°C with
a minimum footprint layout, the maximum input voltage for a
set output current can be determined as follows:
The error flag circuit was designed essentially to work with a
capacitor to ground to act as a power-on reset generator,
signaling a power-good situation once the regulated voltage
was up and/or out of a fault condition. This capacitor delays
the error signal from pulling high, allowing the down stream
circuits time to stablilize. When the error flag is pulled-up to
June 2003
θJA Recommended
Minimum Footprint
 125°C − 50°C 
PD(max) = 

 235°C/W 
PD(max) = 315mW
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MIC5256
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Micrel
Fixed Regulator Applications
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 3.0V 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.
315mW = (VIN – 3.0V) 150mA
47kΩ
VIN
CIN= 1.0µF
Ceramic
1
5
2
3
4
VOUT
COUT = 1.0µF
Ceramic
Figure 1. Low-Noise Fixed Voltage Application
315mW = VIN ·150mA – 450mW
810mW = VIN ·150mA
VIN(max) = 5.4V
Figure 1 shows a standard low-noise configuration with a
47kΩ pull-up resistor from the error flag to the input voltage
and a pull-down capacitor to ground for the purpose of fault
indication. EN (Pin 3) is connected to IN (Pin 1) for an
application where enable/shutdown is not required. COUT =
1.0µF minimum.
Therefore, a 3.0V 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
effects on voltage regulators, refer to the Regulator Thermals
section of Micrel’s Designing with Low-Dropout Voltage Regulators handbook.
MIC5256
MIC5256-x.xBM5
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MIC5256
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 (M5)
1.90BSC
2.90BSC
0.30
0.45
DIMENSIONS:
Millimeter
1.90BSC
0.90
0.80
1.00
0.90
1.60BSC
0.20
0.12
0.10
0.01
1.60BSC
0.30
0.50
1.90BSC
TSOT-23-5 (D5)
MICREL, INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131
+ 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.
© 2003 Micrel, Incorporated
June 2003
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MIC5256