MIC5325
Low V
IN
/V
OUT
400mA ULDO™
with Ultra-Low IQ
ULDO is a trademark of Micrel, Inc
MLF and MicroLeadFrame 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
April 2008
M9999-040308-A
General Description
The MIC5325 is a high performance, µCap low dropout
regulator, offering ultra-low operating current while
maintaining very fast transient response. The MIC5325
can source up to 400mA of output current and allows a low
input supply voltage source to increase system efficiency.
Ideal for battery operated applications; the MIC5325 offers
high accuracy, extremely low dropout voltage, and low
ground current at all load conditions. The MIC5325 can
also be put into a zero-off-mode current state, drawing
virtually no current when disabled.
The MIC5325 is available in fixed output voltages in the
6-pin 2mm x 2mm Thin MLF
®
leadless package.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Wide input voltage range: 1.7V to 5.5V
• Stable with 1µF ceramic output capacitor
• Ultra-low dropout voltage ULDO™ 110mV @ 400mA
• ±2% voltage accuracy over temperature
• Bias supply voltage range: 2.5V to 5.5V
• Adjustable output voltage range: 0.8V to 2.0V
• Ultra-low ground current 35µA typical
• 400mA maximum output current per LDO
• Very fast transient response
• Thermal shutdown and current limit protection
• Tiny 6-pin 2mm x 2mm Thin MLF
®
package
Applications
• Low power handheld devices
• Portable electronics
• GPS receivers
• Post regulator
___________________________________________________________________________________________________________
Typical Application
MIC5325-xxYMT
VBIAS
EN
VOUT
BYP
VIN
GND
MIC23050
High Efficiency
DC-to-DC
Buck
Li-ion
2.7...4.2V
C
BIAS
1µF
C
IN
1µF C
BYP
10nF
C
OUT
1µF
Micrel, Inc. MIC5325
April 2008
2
M9999-040308-A
Ordering Information
Part Number Marking Voltage Temperature Rang e Package Lead Finish
MIC5325-1.2YMT QG4 1.2V –40° to +125°C 6-Pin 2mm x 2mm Thin MLF
®
Pb-Free
MIC5325-1.5YMT QGF 1.5V –40° to +125°C 6-Pin 2mm x 2mm Thin MLF
®
Pb-Free
MIC5325-1.8YMT QGG 1.8V –40° to +125°C 6-Pin 2mm x 2mm Thin MLF
®
Pb-Free
Note:
1. Other voltages available. Contact Micrel for details.
2. Contact Marketing for ADJ version availability.
3. ▲ = Pin 1 identifier.
Pin Configur ation
1VBIAS
GND
IN
6EN
BYP/ADJ
OUT
5
4
2
3
6-Pin 2mm x 2mm Thin MLF
®
(MT)
Pin Description
Pin Number Pin Name Pin Function
1 VBIAS Bias Input Voltage.
2 GND Ground
3 IN Power Input for LDO.
4 OUT Output of regulator.
5 BYP/ADJ
Bypass: Connect a capacitor to ground to reduce noise and reduce ripple
rejection.
Adjust: Feedback input from external resistor divider.
6 EN
Enable Input: Active High Input. Logic High = On; Logic Low = Off; Do not leave
floating.
Micrel, Inc. MIC5325
April 2008
3 M9999-040308-A
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
)............................................ 0V to V
BIAS
Bias Voltage (V
BIAS
)................................................ 0V to 6V
Enable Voltage (V
EN
)........................................... 0V to V
BIAS
Power Dissipation (P
D
) ........................... Internally Limited
(3)
Lead Temperature (soldering, 10 µsec.).................... 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
ESD Rating
(4)
.................................................................. 2kV
Operating Ratings(2)
Supply Voltage (V
IN
)......................................... 1.7V to V
BIAS
Bias Voltage (V
BIAS
).......................................... 2.5V to 5.5V
Enable Voltage (V
EN
)........................................... 0V to V
BIAS
Junction Temperature (T
J
) ........................–40°C to +125°C
Junction Thermal Resistance
2x2 Thin MLF-6 (
θ
JA
) .........................................90°C/W
Electrical Characteristics(5)
V
BIAS
= 3.6V; V
IN
= V
OUT
+ 1V; C
OUT
= 1µF; I
OUT
= 100µA; T
J
= 25°C, bold values indicate –40°C to +125°C, unless noted.
Parameter Condition Min Typ Max Units
Output Voltage Accuracy Variation from nominal V
OUT
–2.0
+2.0
%
Reference Voltage ADJ pin voltage
0.7595
0.775
0.7905
V
V
BIAS
Line Regulation V
BIAS
= 3.6V to 5.5V, V
IN
= V
OUT
+1V 0.03
0.6
%/V
V
IN
Line Regulation V
BIAS
= 3.6V to 5.5V, V
IN
= V
OUT
+1V to 5.5V 0.02
0.6
%/V
Load Regulation I
OUT
= 100µA to 400mA 0.3
2
%
V
IN
Dropout Voltage I
OUT
= 400mA 110
250
mV
Ground Pin Current I
OUT
= 100µA to 400mA, V
IN
= V
EN
, V
BIAS
= 5.5V 35
55
µA
Ground Pin Current in Shutdown V
EN
≤ 0.2V 0.01 1 µA
Ripple Rejection f = up to 1kHz; C
OUT
= 1.0µF; no C
BYP
f = up to 1kHz; C
OUT
= 1.0µF; C
BYP
= 10nF
f = 1kHz – 20kHz; C
OUT
= 1.0uF; C
BYP
= 10nF
50
60
65
40
dB
dB
dB
Current Limit V
OUT
= 0V 450 680 mA
Output Voltage Noise C
OUT
= 1µF, C
BYP
= 10nF, 10Hz to 100kHz 30 µV
RMS
Enable Inputs (EN)
Logic Low
0.2
V Enable Input Voltage
Logic High
1.2
V
V
IL
≤ 0.2V 0.01
µA Enable Input Current
V
IH
≥ 1.0V 0.02
µA
Turn-on Time C
OUT
= 1µF; C
BYP
= 10nF 150
500
µs
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. The maximum allowable power dissipation of any T
A
(ambient temperature) is P
D(max)
= T
J(max)
– T
A
) / θ
JA
. Exceeding the maximum allowable power
dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.
4. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
5. Specification for packaged product only.
Micrel, Inc. MIC5325
April 2008
4 M9999-040308-A
Typical Characteristics
0
-20
-40
-60
-80
-100
-120
Power Supply
Rejection Ratio (VIN)
1
FREQUENCY (kHz)
0.1 10 100 1,000
V
IN
= V
OUT
+1V
V
OUT
= 1.2V
C
OUT
= 1µF
C
BYP
= 0.01µF
100mA
50mA
100µA
100µA
(NO BYP)
300mA
400mA
0
-20
-40
-60
-80
-100
-120
Power Supply
Rejection Ratio (VBIAS)
1
FREQUENCY (kHz)
0.1 10 100 1,000
V
IN
= V
OUT
+1V
V
OUT
= 1.2V
C
OUT
= 1µF
C
BYP
= 0.01µF
100µA
100µA
(NO BYP)
400mA
0
1
2
3
4
5
6
7
8
9
10
1.5 2 2.5 3 3.5 4 4.5 5 5.5
VIN (V)
Ground Current (VIN)
vs. VIN
V
BIAS
= 5.5V
V
OUT
= 1.8V
C
OUT
= 1µF
C
BYP
= 0.01µF
0
1
2
3
4
5
6
7
8
9
10
Ground Current (VIN)
vs. Output Current
V
IN
= 2.8V
V
OUT
= 1.8V
C
OUT
= 1µF
C
BYP
= 0.01µF
0 50 100 150 200 250 300 350 400
OUTPUT CURRENT (mA)
0
2
4
6
8
10
12
14
16
18
Ground Current (VBIAS)
vs. Output Current
V
BIAS
= 3.6V
V
IN
= 2.8V
V
OUT
= 1.8V
C
OUT
= 1µF
C
BYP
= 0.01µF
0 50 100 150 200 250 300 350 400
OUTPUT CURRENT (mA)
10
12
14
16
18
20
22
24
26
28
30
Ground Current (Total)
vs. Output Current
0 50 100 150 200 250 300 350 400
OUTPUT CURRENT (mA)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
VIN (V)
Output Voltage
vs. V
IN
V
BIAS
= 5.5V
V
OUT
= 1.8V
C
OUT
= 1µF
400mA
100µA
0
20
60
80
100
120
140
Dropout Voltage
vs. Temperature
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
40
400mA
200mA
100mA
0
20
40
60
80
100
120
140
Dropout Voltage
vs. Output Current
V
BIAS
= 3.6V
V
IN
= 2.8V
C
OUT
= 1µF
C
BYP
= 0.01µF
C
BAIS
= 1µF
C
IN
= 1µF
0 50 100 150 200 250 300 350 400
OUTPUT CURRENT (mA)
0
2
4
6
8
10
12
14
16
18
20
Ground Current (V
IN
)
vs. Temperature
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
V
BIAS
= 3.6V
V
IN
= 2.8V
V
OUT
= 1.8V
400mA
100µA
600
625
650
675
700
725
750
775
800
825
850
875
900
1.5 2 2.5 3 3.5 4 4.5 5 5.5
VIN (V)
Current Limit
vs. V
IN
V
BIAS
= 5.5V
V
OUT
= 1.8V
C
OUT
= 1µF
C
IN
= 1µF
1.6
1.65
1.7
1.75
1.8
Output Voltage
vs. Output Current
V
BIAS
= 3.6V
V
IN
= 2.8V
C
OUT
= 1µF
C
BYP
= 0.01µF
C
IN
= 1µF
0 50 100 150 200 250 300 350 400
OUTPUT CURRENT (mA)
Micrel, Inc. MIC5325
April 2008
5 M9999-040308-A
Typical Characteristics (continued)
1.10
1.15
1.20
1.25
1.30
Output Voltage
vs. Temperature
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
V
IN
= 2.2V
V
BIAS
= 3.6V
V
OUT
= 1.2V
C
OUT
= 1µF
I
OUT
= 100µA
0.700
0.725
0.750
0.800
0.825
0.850
0.875
0.900
Reference Voltage
vs. Temperature
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
V
IN
= 2.2V
V
BIAS
= 3.6V
V
OUT
= 1.2V
C
OUT
= 1µF
I
OUT
= 100µA
0.775
0
2
4
6
8
10
12
14
16
18
20
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
ENABLE VOLTAGE (V)
Bias C urrent
vs. Enable Voltage
V
BIAS
= 3.6V
V
IN
= 2.8V
V
OUT
= 1.8V
C
IN
= 1µF
C
OUT
= 1µF
C
BYP
= 0.01µF
400mA
100µA
0.01
0.1
1
10
Output Nois e
Spectral D ensit y
10 1K 10K 100K
FREQUENCY (Hz)
100 1M
VIN = 4.5V
VOUT = 1.8V
COUT = 1µF
CBYP = 0.01µF
Noise (10Hz to 1MHz) = 59µV
RMS
Micrel, Inc. MIC5325
April 2008
6 M9999-040308-A
Functional Characteristics
Micrel, Inc. MIC5325
April 2008
7 M9999-040308-A
Functional Diagram
VBIAS
VIN
EN
GND
VOUT
BYP
LDO
CURRENT
LIMIT
QUICK START
REFERENCE
THERMAL
LIMIT
Micrel, Inc. MIC5325
April 2008
8
M9999-040308-A
Application Information
The MIC5325 is a high performance, low-dropout linear
regulator designed for low current applications requiring
fast transient response. The MIC5325 utilizes two input
supplies, significantly reducing dropout voltage, perfect for
low-voltage, DC-to-DC conversion. The MIC5325 requires
a minimum of external components.
The MIC5325 regulator is fully protected from damage
due to fault conditions, offering linear current limiting and
thermal shutdown.
Bias Supply Voltage
V
BIAS
, requiring relatively light current, provides power to
the control portion of the MIC5325. Bypassing on the bias
pin is recommended to improve performance of the
regulator during line and load transients. 1µF ceramic
capacitor from V
BIAS
-to-ground helps reduce high
frequency noise from being injected into the control
circuitry from the bias rail and is good design practice.
Input Supply Voltage
V
IN
provides the supply to power the LDO. The minimum
input voltage is 1.7V, allowing conversion from low
voltage supplies.
Output Capacitor
The MIC5325 requires an output capacitor of 1µF or
greater to maintain stability. The design is optimized for
use with low-ESR ceramic chip capacitors. High ESR
capacitors may cause high frequency oscillation. 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.
X7R/X5R dielectric-type ceramic capacitors are recom-
mended 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 an X7R ceramic capacitor to ensure
the same minimum capacitance over the equivalent
operating temperature range.
Input Capacitor
The MIC5325 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.
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, further
reducing noise and improving PSRR. Turn-on time
increases slightly with respect to bypass capacitance. A
unique, quick-start circuit allows the MIC5325 to drive a
large capacitor on the bypass pin without significantly
slowing turn-on time.
Minimum Load Current
The MIC5325, unlike most other regulators, does not
require a minimum load to maintain output voltage
regulation.
Enable/Shutdown
The MIC5325 comes with a single 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. The
active-high enable pin uses CMOS technology and the
enable pin cannot be left floating; a floating enable pin
may cause an indeterminate state on the output.
Thermal Considerations
The MIC5325 is designed to provide 400mA of continuous
current in a very small package. Maximum ambient
operating temperature can be calculated based on the
output current and the voltage drop across the part. Given
that the input voltage is 1.8V, the output voltage is 1.2V
and the output current = 400mA. The actual power
dissipation of the regulator circuit can be determined
using the equation:
P
D
= (V
IN
– V
OUT1
) I
OUT
+ V
IN
I
GND
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.
P
D
= (1.8V – 1.2V) × 400mA
P
D
= 0.18W
To determine the maximum ambient operating
temperature of the package, use the junction-to-ambient
thermal resistance of the device and the following basic
equation:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
=
JA
AJ(max)
D(max)
TT
P
θ
T
J(max)
= 125°C, the maximum junction temperature of the
die θ
JA
thermal resistance = 90°C/W.
Micrel, Inc. MIC5325
April 2008
9
M9999-040308-A
U1
MIC5325-YMT
VBIAS
BYP/ADJ
VOUT
GND
VIN
C1
1µF/6.3V
C2
1µF/6.3V
EN
VBIAS
VIN VOUT
C3
0.01µF/6.3V
C4
1µF/6.3V
J1
V
BIAS
J2
GND
J3
VIN
J6
EN
J4
VO
J5
GND
R3
10k
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1, C2, C4 VJ0603G105KXYCW1BC Vishay
(1)
Capacitor, 1µF, 6.3V, Size 0603 3
C3 VJ0603Y103KXQCW1BC Murata
(2)
Capacitor, 0.01µF, 10V, Size 0603 1
R3 CRCW060310K0FKEA Vishay Dale
(1)
Resistor, 10k, 1%, 1/16W, Size 0603 1
U1 MIC5325-xxYMT Micrel, Inc.
(3)
400mA ULDO™ with Ultra Low IQ 1
Notes:
1. Vishay: www.vishay.com
2. Murata: www.murata.com
3. Micrel, Inc.: www.micrel.com
Micrel, Inc. MIC5325
April 2008
10
M9999-040308-A
PCB Layout Recommendations
Top Layer
Bottom Layer
Micrel, Inc. MIC5325
April 2008
11
M9999-040308-A
Package Information
6-Pin 2mm x 2mm Thin MLF
®
(MT)
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.
© 2007 Micrel, Incorporated.
