UNISONIC TECHNOLOGIES CO., LTD
USR1021
Preliminary
LINEAR INTEGRATED CIRCUIT
3A SYNCHRONOUS BUCK
REGULATOR
DESCRIPTION
The UTC
USR1021
is a high efficiency, 3A synchronous buck
regulator. The UTC
USR1021
works from a 6V to 18V input
voltage range, and provides up to 3A of continuous output current
with an output voltage adjustable down to 0.8V.
The UTC
USR1021
comes in an SOP-8 packages and is rated
over a -40°C~+85°C ambient temperature range.
SOP-8
FEATURES
* 6V~18V operating input voltage range
* High efficiency
* Internal soft start
* 1.5% initial output accuracy
* Output voltage adjustable to 0.8V
* 3A continuous output current
* Cycle-by-cycle current limit
* 500kHz PWM operation
* Thermal shutdown
* Short-circuit protection
ORDERING INFORMATION
Ordering Number
Package
SOP-8
SOP-8
Packing
Tape Reel
Tube
Lead Free
Halogen Free
USR1021L-S08-R
USR1021G-S08-R
USR1021L-S08-T
USR1021G-S08-T
Note: xx: Output Voltage, refer to Marking Information.
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Copyright © 2013 Unisonic Technologies Co., Ltd
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USR1021
PIN CONFIGURATION
Preliminary
LINEAR INTEGRATED CIRCUIT
PIN DESCRIPTION
PIN NAME
PGND
V
IN
AGND
FB
COMP
EN
LX
DESCRIPTION
Power ground
Supply voltage input
Reference connectio for controller section
Feedback voltage
Compensation pin
Enable pin
Switch pin
PIN NO.
1
2
3
4
5
6
7, 8
BLOCK DIAGRAM
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USR1021
PARAMETER
Preliminary
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATING
SYMBOL
V
IN
RATINGS
UNIT
Supply Voltage
18
V
LX to AGND
-0.7~V
IN
+0.3
V
EN to AGND
-0.3~V
IN
+0.3
V
FB to AGND
-0.3~6.0
V
COMP to AGND
-0.3~6.0
V
PGND to AGND
-0.3~+0.3
V
Junction Temperature
T
J
+150
°C
Storage Temperature
T
STG
-65~+150
°C
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
THERMAL DATA
SYMBOL
θ
JA
RATINGS
87
UNIT
°С/W
PARAMETER
Junction to Ambient (Note 2)
RECOMMENDED OPERATING CONDIIONS
PARAMETER
SYMBOL
V
IN
T
A
RATINGS
6~18
0.8~V
IN
-40~+85
UNIT
V
V
°C
Supply Voltage
Output Voltage Range
Ambient Temperature
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
I
IN
I
OFF
V
FB
TEST CONDITIONS
I
OUT
=0, V
FB
=1.2V, V
EN
>2V
V
EN
=0V
T
A
=25 °C
MIN
6
TYP
3.5
1
0.8
0.5
1
MAX UNIT
18
V
5
mA
10
µA
0.812
V
%
%
200
nA
0.6
V
V
ms
600
150
7
180
I
LIMT
3.5
kHz
%
ns
A/V
µA/V
(T
A
=25°C, V
IN
=V
EN
=12V, V
OUT
=3.3V, unless otherwise specified) (Note 3)
PARAMETER
Supply Voltage
Supply Current (Quiescent)
Shutdown Supply Current
Feedback Voltage
Load Regulation
Line Regulation
Feedback Voltage Input Current
EN Input Threshold
SS Time
MODULATOR
Frequency
Maximum Duty Cycle
Controllable Minimum On Time
Current Sense Transconductance
Error Amplifier Transconductance
PROTECTION
Current Limit
0.788
I
FB
V
EN
Off Threshold
On Threshold
C
SS
=16nF
2
2
400
85
500
f
O
D
MAX
T
MIN
4.5
A
150
°C
T
J
Rising
Over-Temperature Shutdown Limit
T
J
Falling
100
°C
Notes: 1. Devices are inherently ESD sensitive, handling precautions are required. Human body model rating: 1.5
kΩ in series with 100pF.
2
2. The value of
θ
JA
is measured with the device mounted on a 1-in FR-4 board with 2oz. Copper, in a still air
environment with T
A
=25°C. The value in any given application depends on the user’s specific board
design.
3. Specification in BOLD indicate an ambient temperature range of -40°C~+85°C. These specifications are
guaranteed by design.
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USR1021
V
IN
C1
22µF
Ceramic
Preliminary
LINEAR INTEGRATED CIRCUIT
TYPICAL APPLICATION CIRCUIT
V
IN
EN
COMP
R
C
C
C
AGND
PGND
UTC USR1021
FB
LX
L1 4.7µH
V
OUT
R1
C2, C3
22µF
Ceramic
R2
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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