X RP 7 6 5 9
1 . 5 A 1 8 V 1 . 4 M H z N o n Sy n c h r o n o u s S t e p - D o w n R e g u l a t o r
August 2012
Rev. 1. 2.0
GENERAL DESCRIPTION
The XRP7659 is a current - mode PWM step -
down (buck)
voltage regulator capable of
delivering an output current up to 1.5Amps. A
wide 4.5V to 18V input voltage range allows
for single supply operation from industry
standard 5V , 9.6V and 12V power rails.
With a 1. 4MHz constant operatin g frequency,
integrated high - side
MOSFET and loop
compensation , the
XRP7659 reduces the
overall component count and solution
footprint. Current -mode control provides fast
transient response and cycle
- by - cycle current
limit. An integrated soft - start prevents inrush
current at turn - on, and in shutdown mode the
supply curren t drops to 0.1 µA.
Built - in output over voltage (open load), over
t emperature, cycle - by - cycle over -current and
under voltage lockout (UVLO) pr
otection
insure safe operation
under abnormal
operating conditions.
The XRP76 59 is a pin and function compatible
(V
IN
<18V) device to Monolithic Power Systems
MP2359 .
The XRP76 59 is offered in a RoHS compliant,
halogen free 6- pin SOT- 23 package.
A PPLICATIONS
Distributed Power Architectures
Point of Load Converters
Audio - Video Equipment
Medical & Industrial
Equipment
FEATURES
1.5A Continuous Output Current
4.5V to 18V Wide Input Voltage
PWM Current
- Mode Control
1.4MHz Constant Operation
Up to 92% Efficiency
Adjustable Output Voltage
0.81V to 15V Range
± 3% Accuracy
Enable Function
and Soft Start
Built - in Thermal, Over
- Current, UVLO
and Output Over
- Voltage Protection
Pin/Function Compatible to MP2359
Free 6 - Pin SOT - 23 Package
TYPICAL APPLICATION
DIAGRAM
Fig. 1: XRP7659 Application Diagram
Exar Corporation
48720 Kato Road, Fremont CA 94538, USA
Tel. +1 510 668
- 70 00
www.exar.com
Fax. +1 510 668 - 70 01
X RP 7 6 5 9
1 . 5 A 1 8 V 1 . 4 M H z N o n Sy n c h r o n o u s S t e p - D o w n R e g u l a t o r
ABSOLUTE MAXIMUM RAT
INGS
OPERATING RATINGS
Input Voltage Range V
IN
................................
4.5V to 18 V
Maximum Output Current
I
OUT
(Min) .........................
1.5A
Ambient Temperature Range ...................
- 40°C to + 85 °C
..... 220 °C/W
JA
................................
These are stress ratings only and functional operation of
the device at these ratings or any other above those
indicated in the operation sections of the specifications
below is not implied.
Exposure to absolute maximum
rating conditions for extended periods of time may affect
reliability.
V
IN
................................
............................
- 0.3V to 2 0V
V
EN
................................
....................
- 0.3V to V
IN
+0.3 V
V
SW
................................
................................
....... 21 V
V
BS
................................
.......................
- 0.3V to V
SW
+6 V
V
FB
................................
..............................
- 0.3V to 6 V
Operating Junction Temperature ............................
150°C
Storage Temperature ..............................
- 65°C to 150°C
Lead Temperature (Soldering, 10 sec)
....................
26 0°C
Power Dissipation ................................
Internally Limited
ESD Rating (HBM - Human Body Model) ....................
2kV
ESD Rating (MM - Machine Model) ...........................
500V
ELECTRICAL SPECIFICA
TIONS
J
Specifications are for an Operating Junction Temperature of T
= 25°C only; limits applying over the full Operating Junction
teed through test, design, or statistical
correlation. Typical values represent the most likely parametric norm at T
J
= 25°C, and are provided for reference purposes
only. Unless otherwise indicated, V
IN
= V
EN
= 12V, V
OUT
= 3.3V .
Parameter
V
IN
, Input Voltage
I
Q
, Quiescent Current
I
SHDN
, Shutdown Supply Current
V
FB
, Feedback Voltage
V
FBOV
, Feedback Overvoltage Threshold
I
FB
, Feedback Bias Current
R
DSON
, Switch On - resistance
I
LEAK
, Switch Leakage Current
I
LIM
, Switch Current Limit
V
ENH
, EN Pin Threshold
V
ENL
, EN Pin Threshold
V
UVLO
, Input UVLO Threshold
V
HYS
, Input UVLO Hysteresis
f
OSC1
, Oscillator frequency
f
OSC2
, Oscillator frequency
D
MAX
, Maximum Duty Cycle
D
MIN
, Minimum Duty Cycle
t
ON
, Minimum On Time
T
OTSD
, Thermal Shutdown
t
SS
, Soft - start time
(1)
(1)
(1)
(1)
(1)
Min.
4.5
Typ.
0.8
0.1
Max.
18
1.1
1.0
0.835
+0.1
Units
V
mA
µA
V
V
µA
µA
A
V
V
FB
=0.85V
I
SW
=1A
V
FB
=0.9V
V
EN
=0V
Conditions
0.785
- 0.1
0.810
0.972
0.35
0.1
10
V
IN
=18V, V
EN
=0V
1.8
1.5
2.4
0.4
V
V
V
MHz
kHz
%
Short Circuit
V
FB
=0.6V
V
FB
=0.9V
V
IN
Rising
3.3
1.1
3.8
0.2
1.4
460
90
4.3
1.7
0
100
160
20
200
SS
%
ns
°C
°C
µs
T
HYS
, Thermal Shutdown Hysteresis
Note 1: R
DSON
, t
ON
, T
OTSD
, T
HYS
and t
are guaranteed by design.
© 2012 Exar Corporation
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Rev. 1. 2.0
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1 . 5 A 1 8 V 1 . 4 M H z N o n Sy n c h r o n o u s S t e p - D o w n R e g u l a t o r
BLOCK DIAGRAM
Fig. 2: XRP7659 Block Diagram
PIN ASSIGNMENT
Fig. 3: XRP7659 Pin Assignment
PIN DESCRIPTION
Name
BS
GND
FB
Pin Number
1
2
3
Description
Boots trap pin.
Connect a 10nF b ootstrap capacitor between BS and SW pin
s. The voltage across
the bootstrap capacitor drives the internal high
- side MOSFET.
Ground pin.
Feedback pin.
Connect to a resistor divider to program the
output voltage. If V
FB
exceeds 0.972V
the OVP is triggered. If V
drops below 0.25V the short circuit protection is
FB
activated .
Enable Input Pin .
Forcing this pin above 1.5V enables the IC. Forcing the pin below 0.4V shuts down
the IC. For automatic
Power Input Pin.
Must be closely decoupled to GND pin with a
Power switch output pin.
Connect to inductor and bootstrap capacitor.
10µF/25V or greater ceramic capacitor
.
EN
IN
SW
4
5
6
ORDERING INFORMATION
Part Number
XRP7659IS TR- F
XRP7659EVB
-
Temperature
Range
A
Marking
LCWW
X
Package
SOT23 - 6
Packing
Quantity
3K/Tape & Reel
Note 1
Halogen Free
Note 2
XRP7659 Evaluation Board
; when applicable.
© 2012 Exar Corporation
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Rev. 1. 2.0
X RP 7 6 5 9
1 . 5 A 1 8 V 1 . 4 M H z N o n Sy n c h r o n o u s S t e p - D o w n R e g u l a t o r
TYPICAL PERFORMANCE
CHARACTERISTICS
T
J
= T
A
All data taken at V
IN
= 12 V, V
EN
=5V, V
OUT
=3.3V,
Application Information section of this datasheet.
= 25°C, unless otherwise specified
- Schematic and BOM from
Fig. 4: Efficien cy versus Output Current
, V
IN
=12V
Fig. 5: Quiescent Current versus Temperature
Fig. 6: Feedback Voltage versus Temperature
Fig. 7: Output Voltage versus Output Current
Fig. 8: Output Voltage versus Input Voltage
Fig. 9: Maximum Output Current versus Input Voltage
© 2012 Exar Corporation
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Rev. 1. 2.0
X RP 7 6 5 9
1 . 5 A 1 8 V 1 . 4 M H z N o n Sy n c h r o n o u s S t e p - D o w n R e g u l a t o r
Fig. 10 : Output Ripple at I
OUT
=1.5A
Fig. 11 : Load Step
Transient , I
OUT
= 1A to 1.5A
Fig. 12 : Enable Turn - on Characteristic
Fig. 13 : Enable Turn - off Characteristic
Fig. 14 : Onset of
Short - circuit Protection
I
OUT
=1.5A
Fig. 15 : Short - circuit recovery
R
LOAD
© 2012 Exar Corporation
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Rev. 1. 2.0
