CASC
AEROSEMI
2A,2.3V-6V Input,1.5MHz
Synchronous Step-Down Converter
GENERAL DESCRIPTION
The MT3420C is a 1.5MHz constant frequency,
current mode step-down converter. It is ideal for
portable equipment requiring very high current up
to 2A from single-cell Lithium-ion batteries while
still achieving over 90% efficiency during peak
load conditions. The MT3420C also can run at 100%
duty cycle for low dropout operation, extending
battery life in portable systems while light load
operation provides very low output ripple for noise
sensitive applications. The MT3420C can supply
up to 2A output load current from a 2.3V to 6V
input voltage and the output voltage can be
regulated as low as 0.6V. The high switching
frequency minimizes the size of external
components while keeping switching losses low.
The internal slope compensation setting allows the
device to operate with smaller inductor values to
optimize size and provide efficient operation. The
MT3420C is offered in a low profile 6-pin, SOT
package, and is available in an adjustable version.
This device offers two operation modes, PWM
control and PFM Mode switching control, which
allows a high efficiency over the wider range of the
load.
MT3420C
FEATURES
High Efficiency: Up to 96%
1.5MHz Constant Frequency Operation
2A Output Current
No Schottky Diode Required
2.3V to 6V Input Voltage Range
Output Voltage as Low as 0.6V
PFM Mode for High Efficiency in Light Load
100% Duty Cycle in Dropout Operation
Low Quiescent Current: 40μA
Short Circuit Protection
Thermal Fault Protection
Inrush Current Limit and Soft Start
<1μA Shutdown Current
SOT23-6 package
APPLICATIONS
Cellular and Smart Phones
Wireless and DSL Modems
PDAs
Portable Instruments
Digital Still and Video Cameras
PC Cards
TYPICAL APPLICATION
V
IN
98
96
94
Efficiency(%)
V
OUT
C1
22pF
opt.
V
OUT
=1.8V
VIN
MT3420C
SW
L 2.2μH
R1
200k
1%
R2
100k
1%
92
90
88
86
84
82
80
78
VIN=3.3V
VIN=4.2V
VIN=6V
C
IN
22μF
EN
GND
FB
C
OUT
22μF
Figure 1. Basic Application Circuit
MT3420C Rev1.0
0
0.5
1
1.5
Load Current(A)
2
2.5
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AEROSEMI
MT3420C 2A ,1.5MHz Synchronous Step-Down Converter
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage………………-0.3V to 6.5V
EN,FB Voltages……………..-0.3V to (V
IN
+0.3V)
SW Voltage………………..-0.3V to (V
IN
+0.3V)
Power Dissipation………………………...0.6W
Thermal Resistance
θ
JC
……………….130°C/W
Thermal Resistance
θ
JA
……………….250°C/W
Junction Temperature(Note2)………..........150°C
Operating Temperature Range…….-40°C to 85°C
Lead Temperature(Soldering,10s)………...300°C
Storage Temperature Range……..-65°C to 150°C
ESD HBM(Human Body Mode)……………...2kV
ESD MM(Machine Mode)………………….200V
PACKAGE/ORDER INFORMATION
Order Part Number
TOP VIEW
EN
GND
SW
1
2
3
6
5
4
FB
NC
VIN
Package
Top Marking
MT3420C
SOT23-6
AS20CW
6-LEAD PLASTIC SOT-23
T
JMAX
= 150°C,
θ
JA
= 250°C/ W,
θ
JC
= 130°C/W
PIN DESCRIPTION
Pin Name
EN
GND
SW
VIN
NC
FB
Pin Number
1
2
3
4
5
6
Description
Chip Enable Pin. Drive EN above 1.5V to turn on the part. Drive EN below
0.3V to turn it off. Do not leave EN floating.
Analog ground pin.
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.
Analog supply input pin.
No Connect.
Output Voltage Feedback Pin. An internal resistive divider divides the
output voltage down for comparison to the internal reference voltage.
MT3420C Rev1.0
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AEROSEMI
MT3420C 2A ,1.5MHz Synchronous Step-Down Converter
ELECTRICAL CHARACTERISTICS
(Note 3)
(V
IN
=V
EN
=3.6V, V
OUT
=1.8V, T
A
= 25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
Input Voltage Range
2.3
UVLO Threshold
1.7
Input DC Supply Current
(Note 4)
PWM Mode
V
OUT
= 90%, I
LOAD
=0mA
PFM Mode
V
OUT
= 105%, I
LOAD
=0mA
Shutdown Mode
V
EN
= 0V, V
IN
=4.2V
T
A
= 25°C
0.588
Regulated Feedback
T
A
= 0°C
≤T
A
≤
85°C
0.586
Voltage V
FB
T
A
= -40°C
≤T
A
≤
85°C
0.585
Reference Voltage Line
V
IN
=2.5V to 5.5V
Regulation
V
IN
= 2.5V to 5.5V,
-3
Output Voltage Accuracy
I
OUT
=10mA to 2000mA
Output Voltage Load
I
OUT
=10mA to 2000mA
Regulation
V
OUT
=100%
Oscillation Frequency
V
OUT
=0V
On Resistance of PMOS
I
SW
=100mA
On Resistance of NMOS
I
SW
=-100mA
Peak Current Limit
V
IN
= 3V, V
OUT
=90%
EN Threshold
0.30
EN Leakage Current
SW Leakage Current
V
EN
=0V,V
IN
=V
SW
=5V
TYP
1.9
150
40
0.1
0.600
0.600
0.600
0.1
+3
0.2
1.5
300
100
80
4
1.0
±0.01
±0.01
MAX
6
2.1
300
75
1.0
0.612
0.613
0.615
UNIT
V
V
μA
μA
μA
μA
V
V
V
%/V
% V
OUT
%/A
MHz
kHz
mΩ
mΩ
A
V
μA
μA
150
150
1.50
±1.0
±1.0
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 2: T
J
is calculated from the ambient temperature T
A
and power dissipation P
D
according to the
following formula: T
J
= T
A
+ (P
D
) x (250°C/W).
Note 3: 100% production test at +25°C. Specifications over the temperature range are guaranteed by
design and characterization.
Note 4: Dynamic supply current is higher due to the gate charge being delivered at the switching
frequency.
MT3420C Rev1.0
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AEROSEMI
MT3420C 2A ,1.5MHz Synchronous Step-Down Converter
TYPICAL PERFORMANCE CHARACTERISTICS
100
98
96
94
Efficiency(%)
92
90
88
86
84
82
80
78
0
0.5
1
1.5
Load Current(A)
2
2.5
VIN=3.3V
VIN=4.2V
VIN=6V
100
V
OUT
=1.8V
98
96
94
Efficiency(%)
92
90
88
86
84
82
80
78
0
0.5
1
1.5
Load Current(A)
V
OUT
=3.3V
VIN=3.6V
VIN=4.2V
VIN=6V
2
2.5
PFM MODE (CH1:V
OUT(ripple)
CH2:V
SW
)
PWM MODE(CH1:V
OUT(ripple)
CH2:V
SW
)
MT3420C Rev1.0
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AEROSEMI
MT3420C 2A ,1.5MHz Synchronous Step-Down Converter
FUNCTIONAL BLOCK DIAGRAM
EN
VIN
RS
OSC &
Shutdown
Control
Slope
Compensation
Current
Sensor
Control Logic
Driver
SW
Current Limit
Detector
PWM/PFM
Mode
Detector
FB
Error
Amplifier
PWM
Compartor
Zero Detector
UVLO & Power
Good Detector
VREF
GND
Figure 2. MT3420C Block Diagram
MT3420C Rev1.0
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