MIC5235
Ultra-Low Quiescent Current, 150mA
µCap LDO Regulator
IttyBitty is a registered trademark of Micrel, 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
May 2008
M9999-051508
General Description
The MIC5235 is a 150mA highly accurate, low dropout
regulator with high input voltage and ultra-low ground
current. This combination of high voltage and low ground
current makes the MIC5235 ideal for USB and portable
electronics applications, using 1-cell, 2-cell or 3-cell Li-Ion
battery inputs.
A µCap LDO design, the MIC5235 is stable with either
ceramic or tantalum output capacitor. It only requires a
2.2µF capacitor for stability.
Features of the MIC5235 includes enable input, thermal
shutdown, current limit, reverse battery protection, and
reverse leakage protection.
Available in fixed and adjustable output voltage versions,
the MIC5235 is offered in the IttyBitty
®
SOT-23-5 package
with a junction temperature range of –40°C to +125°C.
Features
• Wide input voltage range: 2.3V to 24V
• Ultra low ground current: 18µA
• Low dropout voltage: 310mV at 150mA
• High output accuracy: ±2.0% over temperature
• µCap: stable with ceramic or tantalum capacitors
• Excellent line and load regulation specifications
• Zero shutdown current
• Reverse battery protection
• Reverse leakage protection
• Thermal shutdown and current limit protection
• IttyBitty
®
SOT-23-5 package
• Adjustable output from 1.24V-20V
Applications
• USB power supply
• Cellular phones
• Keep-alive supply in notebook and portable computers
• Logic supply for high-voltage batteries
• Automotive electronics
• Battery powered systems
Typical Application
15
2
34
C
OUT
=2.2µF
ceramic
I
GND
=18µA
C
IN
=1.0µF
EN
MIC5235BM5
V
IN
V
OUT
=1.8V
R
1
R
2
10
15
20
25
30
35
40
4 9 14 19 24
GROUND CURRENT (µA)
INPUT VOLTAGE (V)
I
OUT
=10µA
I
OUT
=1mA
I
OUT
=100µA
Ultra-Low Current Adjustable Regulator Application
Ground Current vs. Input Voltage
Micrel, Inc. MIC5235
May 2008
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Ordering Information
Part Number Marking Codes
Standard Pb-Free Standard Pb-Free*
Voltage**
Junction
Temp. Range
Package
MIC5235-1.5BM5 MIC5235-1.5YM5 L215 L215 1.5V –40° to +125°C 5-Pin SOT-23
MIC5235-1.8BM5 MIC5235-1.8YM5 L218 L218 1.8V –40° to +125°C 5-Pin SOT-23
MIC5235-2.5BM5 MIC5235-2.5YM5 L225 L225 2.5V –40° to +125°C 5-Pin SOT-23
MIC5235-2.7BM5 MIC5235-2.7YM5 L227 L227 2.7V –40° to +125°C 5-Pin SOT-23
MIC5235-3.0BM5 MIC5235-3.0YM5 L230 L230 3.0V –40° to +125°C 5-Pin SOT-23
MIC5235-3.3BM5 MIC5235-3.3YM5 L233 L233 3.3V –40° to +125°C 5-Pin SOT-23
MIC5235-5.0BM5 MIC5235-5.0YM5 L250 L250 5.0V –40° to +125°C 5-Pin SOT-23
MIC5235BM5 MIC5235YM5 L2AA L2AA Adj. –40° to +125°C 5-Pin SOT-23
* Under bar symbol (_) may not be to scale.
** Contact factory regarding availability for voltages not listed.
Pin Configuration
IN
OUT
NC
EN
L2xx
13
45
2
GND
L2xx
IN
OUT
ADJ
EN
L2xx
13
45
2
GND
L2xx
SOT-23-5 (Fixed)
SOT-23-5 (Adjustable)
Pin Description
Pin Number Pin Name Pin Function
1 IN Supply Input.
2 GND Ground.
3 EN Enable (Input): Logic low = shutdown; logic high = enable.
NC (fixed) No Connect. 4
ADJ (adj.) Adjust (Input): Feedback input. Connect to resistive voltage-divider network.
5 OUT Regulator Output.
Micrel, Inc. MIC5235
May 2008
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Absolute Maximum Ratings(1)
Input Supply Voltage ........................................ –20V to 38V
Enable Input Voltage....................................... –0.3V to 38V
Power Dissipation .....................................Internally Limited
Junction Temperature ...............................–40°C to +125°C
Storage Temperature ................................–65°C to +150°C
ESD Rating
(3)
Operating Ratings(2)
Input Supply Voltage ......................................... 2.3V to 24V
Enable Input Voltage............................................ 0V to 24V
Junction Thermal....................................... –40°C to +125°C
Package Thermal Resistance
SOT-23-5 (θ
JA
).................................................235°C/W
Electrical Characteristics(4)
T
A
= 25°C with V
IN
= V
OUT
+ 1V; I
OUT
= 100µA, Bold values indicate –40°C<T
J
<+125°C; unless otherwise specified.
Parameter Condition Min Typ Max Units
Output Voltage Accuracy Variation from nominal V
OUT
–1.0
–2.0
+1.0
+2.0
%
%
Line Regulation V
IN
= V
OUT
+ 1V to 24V 0.04 %
Load Regulation Load = 100µA to 150mA 0.25 1 %
Dropout Voltage I
OUT
= 100µA
I
OUT
= 50mA
I
OUT
= 100mA
I
OUT
= 150mA
50
230
270
310
300
400
400
450
450
500
mV
mV
mV
mV
mV
mV
mV
Reference Voltage 1.22 1.24 1.25 V
Ground Current I
OUT
= 100µA
I
OUT
= 50mA
I
OUT
= 100mA
I
OUT
= 150mA
18
0.35
1
2
30
35
0.7
2
4
µA
µA
mA
mA
mA
Ground Current in Shutdown V
EN
≤ 0.6V; V
IN
= 24V 0.1 1 µA
Short Circuit Current V
OUT
= 0V 350 500 mA
Output Leakage,
Reverse Polarity Input
Load = 500Ω; V
IN
= –15V –0.1 µA
Enable Input
Input Low Voltage Regulator OFF 0.6 V
Input High Voltage Regulator ON 2.0 V
Enable Input Current V
EN
= 0.6V; Regulator OFF
V
EN
= 2.0V; Regulator ON
V
EN
= 24V; Regulator ON
–1.0 0.01
0.1
0.5
1.0
1.0
2.5
µA
µA
µA
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
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May 2008
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Typical Characteristics
0
10
20
30
40
50
60
70
0.01 0.1 1 10 100 1000
PSRR (dB)
FREQUENCY (kHz)
Power Supply
Rejection Ratio
I
LOAD
=150mA
0
50
100
150
200
250
300
350
0 20 40 60 80 100 120 140 160
DROPOUT VOLTAGE (mV)
OUTPUT CURRENT (mA)
Dropout Voltage
vs. Output Current
0
50
100
150
200
250
300
350
400
450
500
-40 -20 0 20 40 60 80 100 120
DROPOUT VOLTAGE (mV)
TEMPERATURE (°C)
Dropout Voltage
vs. Temperature
I
OUT
=150mA
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5 4
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Dropout
Characteristics
I
LOAD
=100µA
I
LOAD
=75mA
I
LOAD
= 150mA
0
500
1000
1500
2000
2500
3000
0 20 40 60 80 100 120 140 160
GROUND CURRENT (µA)
OUTPUT CURRENT (mA)
Ground Pin Current
vs. Output Current
V
IN
=4V
10
12
14
16
18
20
22
24
26
28
30
0 100 200 300 400 500
GROUND CURRENT (µA)
OUTPUT CURRENT (µA)
Ground Pin Current
vs. Output Current
V
IN
=24V
V
IN
= 12V
V
IN
=4V
40
45
50
55
60
65
70
75
80
-40 -20 0 20 40 60 80 100 120
GROUND CURRENT (µA)
TEMPERATURE (°C)
Ground Pin Current
vs. Temperature
I
LOAD
= 10mA
500
520
540
560
580
600
620
640
660
680
700
-40 -20 0 20 40 60 80 100 120
GROUND CURRENT (µA)
TEMPERATURE (°C)
Ground Pin Current
vs. Temperature
I
LOAD
= 75mA
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
-40 -20 0 20 40 60 80 100 120
GROUND CURRENT (mA)
TEMPERATURE (°C)
Ground Pin Current
vs. Temperature
I
LOAD
= 150mA
0
10
20
30
40
50
60
70
80
90
100
1.5 2 2.5 3 3.5 4
GROUND CURRENT (µA)
INPUT VOLTAGE (V)
Ground Pin Current
vs. Input Voltage
I
OUT
=10mA
I
OUT
=1mA I
OUT
= 100µA
I
OUT
=10µA
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
1.5 2 2.5 3 3.5 4
GROUND CURRENT (µA)
INPUT VOLTAGE (V)
Ground Pin Current
vs. Input Voltage
I
OUT
=150mA
I
OUT
= 75mA
10
15
20
25
30
35
40
4 9 14 19 24
GROUND CURRENT (µA)
INPUT VOLTAGE (V)
Ground Pin Current
vs. Input Voltage
I
OUT
=10µA
I
OUT
=1mA
I
OUT
=100µA
Micrel, Inc. MIC5235
May 2008
5 M9999-051508
Typical Characteristics (continued)
0
20
40
60
80
100
120
-20 -10 0 10
INPUT CURRENT (mA)
SUPPLY VOLTAGE (V)
Input Current
vs. Supply Voltage
V
EN
=5V
R
LOAD
=30
2.95
2.96
2.97
2.98
2.99
3
3.01
3.02
3.03
3.04
3.05
-40 -20 0 20 40 60 80 100 120
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
Output Voltage
vs. Temperature
I
LOAD
= 100µA
0
50
100
150
200
250
300
350
400
-40 -20 0 20 40 60 80 100 120
SHORT CIRCUIT CURRENT (mA)
TEMPERATURE (°C)
Short Circuit Current
vs. Temperature
V
IN
=4V
V
IN
= 4V
150mA
0mA
V
OUT
= 3V
C
OUT
= 4.7µF ceramic
Micrel, Inc. MIC5235
May 2008
6 M9999-051508
Functional Diagram
IN
EN
OUT
GND
ENABLE
V
REF
1.24V
Block Diagram – Fixed Output Voltage
IN
EN
R1
R2
ADJ
OUT
GND
ENABLE
V
REF
1.24V
Block Diagram – Adjustable Output Voltage
Micrel, Inc. MIC5235
May 2008
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Application Information
Enable/Shutdown
The MIC5235 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-mode-current state. In this state, current consumed
by the regulator goes nearly to zero. Forcing the enable
pin high enables the output voltage.
Input Capacitor
The MIC5235 has high input voltage capability up to
24V. The input capacitor must be rated to sustain
voltages that may be used on the input. An input
capacitor may be required when the device is not near
the source power supply or when supplied by a battery.
Small, surface mount, ceramic capacitors can be used
for bypassing. Larger values may be required if the
source supply has high ripple.
Output Capacitor
The MIC5235 requires an output capacitor for stability.
The design requires 2.2µF 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 3Ω. The output capacitor can be
increased without limit. Larger valued capacitors help to
improve transient response.
X7R/X5R dielectric-type 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 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
a X7R ceramic capacitor to ensure the same minimum
capacitance over the equivalent operating temperature
range.
No-Load Stability
The MIC5235 will remain stable and in regulation with no
load unlike many other voltage regulators. This is
especially important in CMOS RAM keep-alive
applications.
Thermal Considerations
The MIC5235 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:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
=
JA
AJ(MAX)
D(MAX) θ
TT
P
T
J(MAX)
is the maximum junction temperature of the die,
125°C, and T
A
is the ambient operating temperature. θ
JA
is layout dependent; Table 1 shows examples of the
junction-to-ambient thermal resistance for the MIC5235.
Package θ
JA
Recommended
Minimum Footprint
SOT-23-5 235°C
Table 1. SOT-23-5 Thermal Resistance
The actual power dissipation of the regulator circuit can
be determined using the equation:
P
D
= (V
IN
– V
OUT
)I
OUT
+ V
IN
I
GND
Substituting P
D(MAX)
for P
D
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 MIC5235-3.0BM5 at
50°C with a minimum footprint layout, the maximum
input voltage for a set output current can be determined
as follows:
⎟
⎠
⎞
⎜
⎝
⎛
°
°−°
=C/W235
C50C125
P
D(MAX)
P
D(MAX)
= 319mW
The junction-to-ambient (θ
JA
) thermal resistance for the
minimum footprint is 235°C/W, from Table 1. It is
important that the maximum power dissipation not be
exceeded to ensure proper operation. Since the
MIC5235 was designed to operate with high input
voltages, careful consideration must be given so as not
to overheat the device. With very high input-to-output
voltage differentials, the output current is limited by the
total power dissipation. Total power dissipation is
calculated using the following equation:
P
D
= (V
IN
– V
OUT
)I
OUT
+ V
IN
× I
GND
Due to the potential for input voltages up to 24V, ground
current must be taken into consideration. If we know the
maximum load current, we can solve for the maximum
input voltage using the maximum power dissipation
calculated for a 50°C ambient, 319mV.
P
D(MAX)
= (V
IN
– V
OUT
)I
OUT
+ V
IN
x I
GND
319mW = (V
IN
– 3V)150mA + V
IN
x 2.8mA
Ground pin current is estimated using the typical
characteristics of the device.
769mW = V
IN
(152.8mA)
V
IN
= 5.03V
For higher current outputs only a lower input voltage will
work for higher ambient temperatures.
Assuming a lower output current of 20mA, the maximum
input voltage can be recalculated:
Micrel, Inc. MIC5235
May 2008
8 M9999-051508
319mW = (V
IN
– 3V)20mA + V
IN
x 0.2mA
379mW = V
IN
x 20.2mA
V
IN
= 18.8V
Maximum input voltage for a 20mA load current at 50°C
ambient temperature is 18.8V, utilizing virtually the entire
operating voltage range of the device.
Adjustable Regulator Application
The MIC5235BM5 can be adjusted from 1.24V to 20V by
using two external resistors (Figure 1). The resistors set
the output voltage based on the following equation:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
+=
2
1
REFOUT
R
R
1VV
Where V
REF
= 1.24V.
Feedback resistor R2 should be no larger than 300kΩ.
OUT
ADJ.
V
IN
R
1
R
2
2.2µF
1.0µF EN
IN
V
OUT
GND
MIC5235BM5
Figure 1. Adjustable Voltage Application
Micrel, Inc. MIC5235
May 2008
9 M9999-051508
Package Information
SOT-23-5 (M5)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +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 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 a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2003 Micrel, Incorporated.