T
echcode
®
General Description
The TD1484A is a monolithic pulse-width-modulated (PWM)
synchronous step-down switch mode regulator with two
internal power MOSFETs. It achieves 3.2A continuous output
current over a wide input supply range with excellent load
and line regulation. Current mode operation provides fast
transient response and eases loop stabilization. Fault
condition protection includes cycle-by-cycle current limit and
thermal shutdown.
This device, available in an SOP8-PP package, provides
a very compact solution with minimal external components.
DATASHEET
3.2A 23V Synchronous Rectified Step-Down Converte
TD1484A
Features
•
•
•
•
•
•
•
•
•
•
3.2A Output Current
Wide 4.75V to 20V Operating Input Range
Integrated 90mΩ Power MOSFET Switches
Output Adjustable from 0.923V to 20V
Up to 93% Efficiency
Programmable Soft-Start
Stable with Low ESR Ceramic Output Capacitors
Fixed 340KHz Frequency
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Applications
•
•
•
•
•
Distributed Power Systems
Networking Systems
FPGA, DSP, ASIC Power Supplies
Green Electronics/ Appliances
Notebook Computers
Package Types
Figure 1. Package Types of TD1484A
October, 20, 2010.
America
SOP8
Techcode Semiconductor, INC.
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echcode
®
Pin Configurations
DATASHEET
3.2A 23V Synchronous Rectified Step-Down Converte
TD1484A
Figure 2 Pin Configuration of TD1484A(Top View)
Pin Description
Pin Number
Pin Name
Description
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel
1
BS
MOSFET switch. Connect a 0.01µF or greater capacitor from SW to BS to power the
high side switch.
2
IN
Supply Voltage. The TD1484A operates from a +4.75V to +23V unregulated input.
C1 is needed to prevent large voltage spikes from appearing at the input.
Power Switching Output. SW is the switching node that supplies power to the output.
Connect the output LC filter from SW to the output load. Note that a capacitor is
required from SW to BS to power the high-side switch.
Ground.
Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB
with a resistive voltage divider from the output voltage. The feedback threshold
is 0.923V.
Compensation Node. COMP is used to compensate the regulation control loop.
Connect a series RC network from COMP to GND to compensate the regulation
control loop. In some cases, an additional capacitor from COMP to GND is
required.
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to
3
4
5
SW
GND
FB
6
COMP
7
EN
turn on the regulator, drive it low to turn it off. Pull up with 100kΩ resistor for
automatic startup.
Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS
8
SS
to GND to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms.
To disable the soft-start feature, leave SS unconnected.
October, 20, 2010.
America Techcode Semiconductor, INC.
2
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T
echcode
®
Ordering Information
TD1484A
□
Circuit Type
DATASHEET
3.2A 23V Synchronous Rectified Step-Down Converte
TD1484A
□
Packing:
Blank：Tube
R:Type and Reel
Package
P:SOP8
Function Block
Figure 3 Function Block Diagram of TD1484A
October, 20, 2010.
America Techcode Semiconductor, INC.
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T
echcode
®
Absolute Maximum Ratings
DATASHEET
3.2A 23V Synchronous Rectified Step-Down Converte
TD1484A
Parameter
Symbol
V
IN
V
SW
V
BS
V
OUT
Value
-0.3 to 23
23
Unit
V
V
V
V
V
º
C
º
C
º
C
º
C
V
º /W
C
º /W
C
Supply Voltage
Switch Node Voltage
Boost Voltage
Output Voltage
All Other Pins
Operating Junction Temperature
Operating Ambient Temperature
Storage Temperature
Lead Temperature (Soldering, 10 sec)
ESD (HBM)
MSL
Thermal Resistance-Junction to Ambient
Thermal Resistance-Junction to Case
V
SW
– 0.3V to
V
SW
+6V
0.923V to 20
–0.3V to +6V
T
J
T
A
T
STG
T
LEAD
150
-40 to 80
-65 to 150
260
2000
RθJA
RθJC
Level3
50
10
October, 20, 2010.
America Techcode Semiconductor, INC.
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T
echcode
®
Electrical Characteristics
V
IN
= 12V, T
a
= 25℃ unless otherwise specified.
DATASHEET
3.2A 23V Synchronous Rectified Step-Down Converte
TD1484A
Parameters
Shutdown Supply Current
Supply Current
Feedback Voltage
Feedback Overvoltage Threshold
Error Amplifier Voltage Gain *
Error Amplifier Transconductance
High-Side Switch On Resistance *
Low-Side Switch On Resistance *
High-Side Switch Leakage
Current
Upper Switch Current Limit
Lower Switch Current Limit
COMP to Current Sense
Transconductance
Oscillation Frequency
Short Circuit Oscillation
Frequency
Maximum Duty Cycle
Minimum On Time *
EN Shutdown Threshold Voltage
EN Shutdown Threshold Voltage
Hysteresis
EN Lockout Threshold Voltage
EN Lockout Hysterisis
Symbol
Test Condition
VEN = 0V
VEN = 2.0V; VFB =
1.0V
Min.
Typ.
1
1.3
Max.
3.0
1.5
0.946
Unit
µA
mA
V
V
V/V
µA/V
mΩ
mΩ
VFB
4.75V ≤ VIN ≤ 20V
0.900
0.923
1.1
AEA
GEA
RDS(ON)1
RDS(ON)2
VEN = 0V, VSW = 0V
Minimum Duty Cycle
From Drain to Source
GCS
Fosc1
Fosc2
DMAX
VFB = 0V
VFB = 1.0V
2.4
∆IC = ±
10µA
400
800
90
90
10
3.4
1.1
µA
A
A
3.5
340
100
90
220
VEN Rising
1.1
1.5
2.0
A/V
KHz
KHz
%
ns
V
210
2.2
2.5
210
2.7
mV
V
mV
October, 20, 2010.
America Techcode Semiconductor, INC.
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