AEROSEMI
CASC
MT1470
2A,4.5V-21V Input,500kHz
Synchronous Step-Down Converter
GENERAL DESCRIPTION
The MT1470 is a fully integrated, high efficiency
2A synchronous rectified step-down converter.
The MT1470 operates at high efficiency over a
wide output current load range.
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.
The MT1470 requires a minimum number of
readily available standard external components
and is available in an 6-pin SOT23 ROHS
compliant package.
FEATURES
High Efficiency: Up to 96%
500KHz Frequency Operation
2A Output Current
No Schottky Diode Required
4.5V to 21V Input Voltage Range
0.8V Reference
Slope Compensated Current Mode Control for
Excellent Line and Load Transient Response
Integrated internal compensation
Stable with Low ESR Ceramic Output
Capacitors
Over Current Protection with Hiccup-Mode
Thermal Shutdown
Inrush Current Limit and Soft Start
Available in SOT23-6 Package
-40°C to +85°C Temperature Range
APPLICATIONS
Distributed Power Systems
Digital Set Top Boxes
Flat Panel Television and Monitors
Wireless and DSL Modems
Notebook Computer
TYPICAL APPLICATION
C2
1uF
V
IN
BS
MT1470
C
IN
22μF
EN
GND
FB
L
10μH
R1
100k
1%
R2
19k
1%
C1
22pF
opt.
V
OUT
VIN
SW
C
OUT
22μF*2
Figure 1. Basic Application Circuit
MT2492 Rev1.0
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AEROSEMI
MT1470 2A ,500kHz Synchronous Step-Down Converter
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage……….………-0.3V to 22V
EN Voltages…………………………-0.3V to 6V
FB Voltages…………………………-0.3V to 6V
SW Voltage………………...-0.3V to (V
IN
+0.5V)
BS Voltage……………..(V
SW
-0.3V) to (V
SW
+5V)
Power Dissipation………………………...0.6W
Thermal Resistance
θ
JC
……………….130°C/W
Thermal Resistance
θ
JA
……………….170°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
GND
SW
VIN
1
2
3
6
5
4
BS
EN
FB
Package
Top Marking
MT1470
SOT23-6
ASTFDC
6-LEAD PLASTIC SOT-23
T
JMAX
= 150°C,
θ
JA
= 170°C/ W,
θ
JC
= 130°C/W
TF:version, D:year, C:week
PIN DESCRIPTION
Pin Name
GND
SW
VIN
FB
EN
BS
Pin Number
1
2
3
4
5
6
Description
Analog ground pin.
Switching Pin.
Power supply Pin
Adjustable version feedback input. Connect FB to the center point of the
external resistor divider
Drive this pin to a logic-high to enable the IC. Drive to a logic-low to
disable the IC and enter micro-power shutdown mode. For automatic
start-up, connect EN to VIN using a 200kΩ resistor.
Bootstrap. A capacitor connected between SW and BS pins is required
to form a floating supply across the high-side switch driver.
MT2492 Rev1.0
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AEROSEMI
MT1470 2A ,500kHz Synchronous Step-Down Converter
ELECTRICAL CHARACTERISTICS
(Note 3)
(V
IN
=12V, V
OUT
=5V, T
A
= 25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
Input Voltage Range
Supply Current in
V
EN
=3.0V, V
FB
=2V
Operation
Supply Current in
V
EN
=0 or EN = GND
Shutdown
Regulated Feedback
T
A
= 25°C, 4.5V≤ V
IN
≤20V
Voltage
High-Side Switch
On-Resistance
Low-Side Switch
On-Resistance
High-Side Switch
V
EN
=0V, V
SW
=0V
Leakage Current
Low-Side Switch
V
EN
=0V, V
SW
=12V
Leakage Current
Upper Switch Current
Minimum Duty Cycle
Limit
OVP
Oscillation Frequency
Maximum Duty Cycle V
FB
=0.7V
Minimum On-Time
Soft-start Time
Tss
Thermal Shutdown
MIN
4.5
TYP
0.6
1
0.776
0.800
90
70
1
1
4.5
400
22
500
92
60
2
180
580
0.824
MAX
21
0.8
UNIT
V
mA
µA
V
mΩ
mΩ
µA
µA
A
V
KHz
%
nS
mS
℃
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 (170°C/W).
Note 3: 100% production test at +25°C. Specifications over the temperature range are guaranteed by
design and characterization.
MT2492 Rev1.0
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AEROSEMI
MT1470 2A ,500kHz Synchronous Step-Down Converter
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs LoadCurrent&Vin=12V
96.00
94.00
Efficiency(%)
92.00
90.00
88.00
86.00
84.00
82.00
0.05
0.1
0.2
0.5
1
Load Current(A)
1.5
2
Output Voltage(V)
5.05
5.03
5.01
4.99
4.97
4.95
0.05
0.1
0.2
0.5
1
Load Current (A)
1.5
2
Load Regulation
Vout=5V
Vin=12V
IN:12V OUT:5V/0.1A
IN:12V OUT:5V/2A
IN:16VOUT:5V/0.1A
IN:16V OUT:5V/2A
MT2492 Rev1.0
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AEROSEMI
FUNCTIONAL BLOCK DIAGRAM
VIN
∑
VCC
MT1470 2A ,500kHz Synchronous Step-Down Converter
+
RSEN
VCC
REGULATOR
-
CURRENT SENSE
AMPLIFIER
BOOST
REGULATOR
BS
OSCILLATOR
HS
DRIVER
COMPARATOR
VCC
ON TIME CONTROL
LOGIC CONTROL
LS
DRIVER
+
EN
1M
REFERENCE
1pF
56pF
400k
-
CURRENT LIMIT
COMPARATOR
SW
FB
+
+
-
ERROR AMPLIFIER
GND
Figure 2. MT1470 Block Diagram
MT2492 Rev1.0
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