UM3501
600mA, 1.2MHz, Synchronous Step-Down DC-DC Converter
UM3501 SOT23-5
UM3501DA DFN6 2.0×
2.0
General Description
UM3501 is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter,
capable of delivering 600mA output current over a wide input voltage range from 2.5V to 5.5V.
The target application of UM3501 is for portable electronic devices that are powered from 1-cell
Li-ion battery or from other power sources within the range such as cellular phones, PDAs and
handy-terminals. Internal synchronous rectifier with low R
DS(ON)
dramatically reduces conduction
loss at PWM mode. No external schottky diode is required in practical application. The UM3501
automatically turns off the synchronous rectifier while the inductor current is low and enters
discontinuous PWM mode. This can increase efficiency at light load condition.
UM3501 enter shutdown mode and consumes less than 0.1uA when EN pin is pulled low. The
operation frequency is set to 1.2MHz. This along with small SOT23-5 package and DFN6 2.0×
2.0
package provides small PCB area application. Other features include lower internal reference
voltage with 2% accuracy, over temperature protection, and over current protection.
Applications
Cellular and Smart Phones
Microprocessors and DSP Core
Supplies
Wireless and DSL Modems
PDAs, GPS
MP3 Player
Portable Instruments
Features
High Efficiency: Up to 90%
1.2MHz Constant Switching Frequency
600mA Output Current
Integrated Main Switch and Synchronous
Rectifier. No Schottky Diode Required
2.5V to 5.5V Input Voltage Range
Low Quiescent Current: 50µ
A
Thermal Fault Protection
<1µ Shutdown Current
A
Lead Free SOT23-5 Package and DFN6
2.0× Package
2.0
Typical Application Circuit
L1
2.2uH
V
IN
C1
4.7uF
VIN
SW
R2
634K
V
OUT
1.8V
C3
10uF
UM3501
EN
GND
FB
R1
316K
________________________________________________________________________
http://www.union-ic.com Rev.06 Feb.2015
1/11
UM3501
Pin Configurations
Top View
5
4
VIN
1
5
SW
5CA
GND
2
1
2
M
3
EN
3
4
FB
UM3501
M: Month Code
SOT23-5
(Top View)
NC
EN
VIN
1
2
3
6
5
4
FB
GND
SW
AAE
UM3501DA
M: Month Code
DFN6 2.0×
2.0
Pin Description
Pin Number
SOT23-5 DFN6 2.0×
2.0
1
2
3
3
5
2
Symbol
VIN
GND
EN
Function
Supply input pin. Must be closely decoupled to GND,
Pin2, with a 4.7μF or greater ceramic capacitor.
Ground.
Regulator enable control input. Drive EN above 1.0V
to turn on the part. Drive EN below 0.4V to turn it
off. In shutdown, all functions are disabled drawing
<1μA supply current. Do not leave EN floating.
Feedback input pin. Connect FB to the center point of
the external resistor divider.
Power switch output. It is the switch node connection to
Inductor.
This pin connects to the drains of the internal P-CH and
N-CH MOSFET switches.
Not connected.
4
6
FB
5
-
4
1
SW
NC
Ordering Information
Part Number
UM3501
UM3501DA
Packaging Type
SOT23-5
DFN6 2.0×
2.0
Marking Code
5CA
AAE
Shipping Qty
3000pcs/7Inch
Tape & Reel
3000pcs/7Inch
Tape & Reel
________________________________________________________________________
http://www.union-ic.com Rev.06 Feb.2015
2/11
M
UM3501
Absolute Maximum Ratings (Note 1)
Symbol
V
IN
V
EN
,V
FB
V
SW
I
SW
T
O
Input Voltage
EN, FB Voltages
SW Voltage
Peak SW Sink and Source Current
Operating Temperature
Parameter
Value
-0.3 to +6.0
-0.3 to V
IN
+0.3
-0.3 to V
IN
+0.3
1.5
-40 to +85
Unit
V
V
V
A
°
C
T
STG
Storage Temperature Range
-65 to +150
°
C
Note 1: Stresses greater than those listed under Maximum Ratings may cause permanent damage
to the device. This is a stress rating only and functional operation of the device at these or
any other conditions above those indicated in the operational sections of this specification
is not implied. Exposure to absolute maximum rating conditions for extended periods
may affect reliability.
Electrical Characteristics (Note 2)
(V
IN
=V
EN
=3.6V, T
A
=+25℃, unless otherwise noted)
Symbol
V
IN
I
Q
(Active)
I
Q
(Shutdown)
Parameter
Input Voltage Range
Input DC Supply
Current
(Active Mode)
Input DC Supply
Current
(Shutdown Mode)
Regulated Feedback
Voltage
FB Input Bias
Current
Reference Voltage
Line
Regulation
Output Voltage Line
Regulation
Output Voltage Load
Regulation
Maximum Output
Current
Oscillator Frequency
R
DS(ON)
of P-CH
MOSFET
R
DS(ON)
of N-CH
MOSFET
Peak Inductor
Current
Test Conditions
Min
2.5
Typ
Max
5.5
Unit
V
μA
V
FB
=0.6V, Iload=0A
50
0.08
0.5880
0.5865
0.5850
0.6000
0.6000
0.6000
1.0
0.6120
0.6135
0.6150
±
30
0.11
0.11
0.0015
600
1.2
0.40
0.35
0.50
0.45
0.40
0.40
V
FB
=0V, V
IN
=4.2V
T
A
= +25º
C
μA
V
FB
0ºC ≤T
A
≤ 85ºC
-40ºC ≤T
A
≤ 85ºC
V
FB
=0.65V
2.5V≤ V
IN
≤ 5.5V,
V
OUT
=V
FB
(R2=0)
2.5V≤ V
IN
≤ 5.5V,
I
OUT
=10mA
100mA≤I
OUT
≤600mA
V
IN
=3.6V, V
OUT
=1.8V
V
FB
=0.6V or
V
OUT
=100%
V
IN
=3.6V,
I
SW
=100mA
V
IN
=3.6,
I
SW
= -100mA
V
IN
=3.0V,
V
FB
=0.5V or
V
OUT
=90%,
Duty Cycle<35%
V
I
FB
nA
%/V
%/V
%/mA
mA
MHz
Ω
Ω
I
O(max)
f
R
DS(ON)
I
P
0.90
1.20
1.90
A
________________________________________________________________________
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UM3501
Electrical Characteristics (continued)
(V
IN
=V
EN
=3.6V, T
A
=+25℃, unless otherwise noted)
Symbol
I
SWL
V
H
V
L
I
ENL
η
(max)
Parameter
SW Leakage
EN High-Level
Threshold
EN Low-Level
Threshold
EN Leakage Current
Max. Efficiency
Thermal Shutdown
Temperature
Test Conditions
V
EN
=0V,
V
IN
=5V ;
V
SW
=0V or 5V
-40ºC ≤T
A
≤ 85ºC
-40ºC ≤T
A
≤ 85ºC
±
0.1
V
IN
=3.6V, V
OUT
=2.5V
90
160
1.0
0.4
±
1
Min
Typ
±
0.01
Max
±
1
Unit
μA
V
V
μA
%
º
C
Note2: 100% production test at +25º Specifications over the temperature range are guaranteed
C.
by design and characterization.
Typical Performance Characteristics
(V
IN
= 3.6V, V
OUT
= 1.8V, L1= 2.2µ C1= 4.7µ C3= 10µ T
A
= +25° unless otherwise
H,
F,
F,
C,
noted.)
Efficiency vs Load Current
Efficiency vs Load Current
100
90
80
100
90
80
Efficiency (%)
Efficiency (%)
70
60
50
40
30
20
10
0
1
10
100
VIN=2.5V
VIN=3.6V
VIN=4.2V
VIN=5.5V
1000
70
60
50
40
30
20
10
0
1
10
100
1000
VOUT=1.8V
VIN=3.6V
VOUT=1.2V
VOUT=1.8V
Output Current (mA)
Output Current (mA)
Efficiency vs Input Voltage
100
90
80
1.80
1.81
Output Voltage vs Load Current
Efficiency (%)
70
60
50
40
30
20
10
0
2.5
3.5
Output Voltage(V)
1.79
1.78
1.77
1.76
1.75
1
10
100
1000
VIN=2.5V
VIN=3.6V
VIN=4.2V
VOUT=1.8V
ILOAD=200mA
ILOAD=400mA
ILOAD=600mA
4.5
5.5
Input Voltage (V)
Output Current (mA)
________________________________________________________________________
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UM3501
Typical Performance Characteristics (continued)
(V
IN
= 3.6V, V
OUT
= 1.8V, L1= 2.2µ C1= 4.7µ C3= 10µ T
A
= +25° unless otherwise
H,
F,
F,
C,
noted.)
Output Voltage vs Input Voltage
1.810
1.805
Output Voltage(V)
1.810
1.805
Output Voltage vs Temperature
1.795
1.790
1.785
1.780
1.775
1.770
2.5
3.5
4.5
Input Voltage(V)
5.5
ILOAD=200mA
ILOAD=400mA
ILOAD=600mA
Output Voltage(V)
1.800
1.800
1.795
1.790
1.785
1.780
1.775
1.770
1.765
1.760
1.755
1.750
-50
-25
0
25
VIN=3.6V,
Iload=100mA
Iload=100mA
50
75
100
125
Temperature(℃)
Supply Current vs Input Voltage
80
70
Frequency vs Input Voltage
1600
1400
Supply Current(uA)
VOUT=1.8V
Iload=100mA
Frequency(kHz)
60
50
40
30
20
10
2.5
3
3.5
4
4.5
5
5.5
1200
1000
800
600
400
200
2.5
3
3.5
4
4.5
5
5.5
6
Supply Voltage(V)
Supply Voltage(V)
Line Transient Response
(Vout=1.8V, Iout=300mA)
VIN=3.5V to 4.5V
Load Transient Response
(Vin=3.6V, Vout=1.8V)
Iout=100mA to 600mA
VOUT 50mV/div
50μs/div
VOUT 100mV/div 50μs/div
________________________________________________________________________
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5/11
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