MT3430
Rev.V1.2
1.4MHz, 3A Synchronous Step-Down DC/DC Converter
FEATURES
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High Efficiency: Up to 95%
1.4MHz Constant Frequency Operation
3A Output Current
No Schottky Diode Required
2.4V to 5.5V Input Voltage Range
Output Voltage as Low as 0.6V
Low Quiescent Current: 40µA
100% Duty Cycle in Dropout Operation
PFM Mode for High Efficiency in
Light Load
Slope Compensated Current Mode Control for
Excellent Line and Load Transient Response
Inrush Current Limit and Soft Start
<1µA Shutdown Current
Available in ESOP-8 package
GENERAL DESCRIPTION
The MT3430 is a constant frequency, current mode
step-down converter.
The device integrates a main
It is ideal for
switch and a synchronous rectifier for high efficiency
without an external Schottky diode.
powering portable equipment that runs from a single
cell Lithium-Ion (Li+) battery. The MT3430 can
supply up to 3A output load current from a 2.5V to
5.5V input voltage and the output voltage can be
regulated as low as 0.6V. The MT3430 can also 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 internal slope
compensation setting allows the device to operate
with smaller inductor values to optimize size and
provide efficient operation. . The MT3430 is available
in adjustable (0.6V to VIN) output voltage.
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.
APPLICATIONS
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Cable/DSL Modems
Computer Peripherals
Network Cards
High Efficiency Conversion from 5V or 3.3 Supply
Set-Top Boxes
Typical Application
Figure 1. Basic Application Circuit
MT3430 Datasheet V1.2 October 2011
1
Aerosemi technology Co.,LTD.
MT3430
Rev.V1.2
Pin Description
PIN
1,6,8
2
NAME
N/C
Vin
No Connect.
FUNCTION
Power Supply Input.
Must be closely decoupled to GND with a 22µF
or greater ceramic capacitor.
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.
Ground pin.
Output Voltage Feedback Pin. An internal resistive divider divides the
output voltage down for comparison to the internal reference voltage.
Chip Enable Pin. Drive EN above 1.5V to turn on the part.
below 0.4V to turn it off. Do not leave EN floating.
Power Ground exposed pad, Must be connected to bare copper
ground plane
Drive EN
3
4
5
SW
GND
FB
7
EN
EP
Package Information
Part Number
SWICHING
FREQUENCY
Temp Range
-40°C to +85°C
OUTPUT
VOLTAGE (V)
OUTPUT
CURRENT (A)
MT3430-ADJ
1.4MHz
ADJ
3
MT3430 Datasheet V1.2 October 2011
2
Aerosemi technology Co.,LTD.
MT3430
Rev.V1.2
Absolute Maximum Ratings
Input Supply Voltage …… -0.3V to 6V
EN,FB Voltages….…-0.3 to (Vin+0.3V)
SW Voltage ………-0.3V to (Vin+0.3V)
Operating Temperature Range … -40°C to +85°C
Lead Temperature(Soldering,10s) ….…..+300°C
Storage Temperature Range ..…-65°C to 150°C
Electrical Characteristics
(V
IN
=V
EN
=3.6V, V
OUT
=1.8V, T
A
= 25°C, unless otherwise noted.)
Parameter
Input Voltage Range
UVLO Threshold
Input DC Supply Current
PWM Mode
PFM Mode
Shutdown Mode
Regulated Feedback
Voltage
Reference Voltage Line
Regulation
Output Voltage Line
Regulation
Output Voltage Load
Regulation
Oscillation Frequency
On Resistance of PMOS
ON Resistance of NMOS
Peak Current Limit
EN Threshold
EN Leakage Current
SW Leakage Current
V
EN
=0V,V
IN
=Vsw=3.6V
Vout=100%
Vout=0V
I
SW
=100mA
I
SW
=-100mA
V
IN
= 3V, Vout=90%
0.40
Vout = 90%, I
load
=0mA
Vout = 105%, I
load
=0mA
V
EN
= 0V, V
IN
=4.2V
T
A
= 25°C
Vin= 2.7V to 5.5V
V
IN
= 2.7V to 5.5V
0.582
160
40
0.1
0.600
0.04
0.04
0.5
1.4
300
0.10
0.09
4
1.0
±0.01
±0.01
1.50
±0.1
±1.0
0.15
0.15
240
70
1.0
0.618
0.40
0.4
Conditions
MIN
2.4
1.7
1.8
TYP
MAX
5.5
1.9
unit
V
V
µA
µA
µA
µA
V
%/V
%
%
MHz
KHz
Ω
Ω
A
V
µA
µA
MT3430 Datasheet V1.2 October 2011
3
Aerosemi technology Co.,LTD.
MT3430
Rev.V1.2
Typical Performance Characteristics
95.00%
100.00%
95.00%
90.00%
90.00%
85.00%
85.00%
80.00%
80.00%
75.00%
75.00%
70.00%
50
10
0
15
0
20
0
30
0
40
0
50
0
60
0
80
0
10
00
12
00
14
00
16
00
18
00
10
70.00%
10
50
10
0
15
0
20
0
30
0
40
0
50
0
60
0
80
0
10
00
12
00
14
00
16
00
18
00
20
00
Vin=5V, Vout=1.8V
Vin=5V, Vout=3.3V
VOUT
10mV/DIV
Vin=3.6V
Vout=1.8V
Iout=50mA
SW
5V/DIV
IL
500mA/DIV
400ns/DIV
PFM MODE
MT3430 Datasheet V1.2 October 2011
4
Aerosemi technology Co.,LTD.
MT3430
Rev.V1.2
Vin=3.6V
Vout=1.8V
Iout=600mA
VOUT
10mV/DIV
SW
5V/DIV
IL
1A/DIV
400ns/DIV
PWM MODE
Start up
Functional Block Diagram
Figure 2. MT3430 Block Diagram
Functional Description
The MT3430 is a high performance 3A
1.4MHz monolithic step-down converter.
The MT3430 requires only three external
power components (Cin, Cout and L). The
adjustable Vout can be programmed with
external feedback to any voltage, ranging
from 0.6V to the input voltage.
MT3430 Datasheet V1.2 October 2011
5
At dropout operation, the converter duty
cycle increases to 100% and the output
voltage tracks the input voltage minus the
Rdson drop of the high-side MOSFET.
The
internal
error
amplifier
and
compensation provides excellent transient
response, load, and line regulation. Soft
start function prevents input inrush current
and output overshoot during start up.
Aerosemi technology Co.,LTD.
Microchip MCU
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