X RP7 6 6 5
3 A 1 8 V S y n c h r o n o u s S t e p - D o w n Co n v e r t e r
March 2013
Rev. 2.0. 1
GENERAL DESCRIPTION
The X RP7665 is a synchronous current
- mode
PWM step down (buck) regulator capable of a
constant output current up to
3 Amps. A wide
4.5 0V to 18V input voltage range allows for
single supply operations from industry
standard 5V and 12V power rails.
With a 340kHz constant operating frequency
and
integrated
high
and
low
side
10
9
, the XRP 7665 reduces
the overall component count
and solution
footprint. Current - mode control provides fast
transient response and cycle
- by - cycle current
limit. An adjustable soft - start prevents inrush
current at turn - on, and in shutdown mode
the
supply current drops to 0.1µ
A.
Built - in output over volta ge (open load) , over
temperature , cycle - by - cycle over current
and
under voltage lockout (UVLO)
protections
insure safe operations under abnormal
operating conditions.
The XRP 7665 is a pin and func tion compatible
device to MP1484 and a 3A pin to pin upgrade
to XRP7664 .
The XRP 7665 is offered in a RoHS compliant,
- pin exposed pad SOIC
package .
APPLICATIONS
Distributed Power Architectures
Point of Load Converters
Audio - Video Equipments
Medical & Industrial Equipments
FEATURES
Pin/Functio
n Compatible to MP148
Output Current
Voltage
4
3 A Continuous
4. 50 V to 18V Wide Input
PWM Current Mode Control
340kHz Constant Operations
Up to 93% Efficiency
Adjustable Output Voltage
0.925V to 16V Range
2.0 % Accuracy
Programmable Soft
Function
- Start and Enable
Built - in Thermal , Over Current , UVLO
and Output Over Voltage
Protections
8 - Pin Exposed Pad
SOIC Package
TYPICAL APPLICATION
DIAGRAM
Fig. 1: XRP7665 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 RP7 6 6 5
3 A 1 8 V S y n c h r o n o u s S t e p - D o w n Co n v e r t e r
ABSOLUTE MAXIMUM RAT
INGS
OPERATING RATINGS
Input Voltage V
IN
................................
....... 4.50V to 18 V
Ambient Operating
Temperature ................
- 40°C to 85 °C
Maximum Output Current
................................
.... 3A min
...... 60 °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 con ditions for extended periods of time may affect
reliability.
Supply Voltage V
IN
................................
...... - 0.3V to 20 V
Switch Node Voltage V
SW
................................
......... 21 V
Boost Voltage V
BS
................................
... - 0.3 to V
SW
+6 V
Enable Voltage V
EN
................................
......... - 0.3 to V
IN
All Other Pins ................................
.............. - 0.3 to +6 V
Junction Temperature
................................
.......... 150°C
Storage Temperature ..............................
- 65°C to 150°C
Lead Temperature (Soldering, 10 sec)
...................
26 0°C
ESD Rating (HBM - Human Body Model) ....................
2kV
ESD Rating (MM - Machine Model) ...........................
200V
Moisture Sensitivity Level (MSL)
................................
... 3
ELECTRICAL SPECIFICA
TIONS
Specifications are for an Operating
Ambient Temperature of T
A
= 25°C only; limits applying over the full
Ambient Operating
T
d through test, design, or statistical
correlation. Typical values represent the most likely parametric norm at T
A
= 25°C, and are provided for reference purposes
only. Unless otherwise indicated, V
= V
EN
= 12 V, V
OUT
=3.3V .
IN
Parameter
Shutdown Supply Current
Quiescent Current
Feedback Voltage
V
FB
0.90 7
- 0.1
EA
Min.
Typ.
0.1
1.2
0.925
1.1
Max.
10
1. 4
0.9 43
0.1
Units
µA
mA
V
V
µA
V/V
µA/V
I
SW
=0.2A&0.7A
V
FB
=1V
V
EN
0.75 V
Conditions
V
EN
= 3V, V
FB
=1V
Feedback Overvoltage Threshold
Feedback Bias Current
Error Amplifier
(Note 1)
Voltage Gain A
400
800
100
100
0.1
4.3
5.6
1.4
5.2
280
340
90
90
0
2.2
2.5
210
3.65
4.00
4. 25
2.7
400
10
Error Amplifier
Transconductance G
EA
High - Side switch On Resistance
R
DSONH
(Note 2)
Low - Side switch On Resistance
R
DSONL
(Note 2)
High - Side switch Leakage
Current
High - Side Switch Current Limit
Low - Side Switch Current Limit
COMP to Current Sense
Transconductance G
CS
Oscillator Frequency
F
OSC1
Short Circuit Oscillator
Frequency F
OSC2
Maximum Duty
Cycle D
MAX
MIN
I
SW
= - 0.2A& -0.7A
µA
A
A
A/V
kHz
kHz
%
%
V
mV
V
V
IN
Rising
V
FB
=0.85V
V
FB
=1V
From Drain to Source
V
IN
=18V, V
EN
=0V,
V
SW
=0V
Minimum Duty Cycle D
EN Enable Threshold Voltage
EN Enable Threshold Voltage
Hysteresis (Note 1)
UVLO Threshold
© 2013 Exar Corporation
2/ 12
Rev. 2.0. 1
X RP7 6 6 5
3 A 1 8 V S y n c h r o n o u s S t e p - D o w n Co n v e r t e r
Parameter
UVLO Hysteresis
Soft - start Current
Soft - start Time (Note 1)
Thermal Shutdown (Note 1)
Thermal Shutdown Hysteresis
(Note 1)
Note 1: Guaranteed by design.
Note 2: R
DSON
=(V
SW1
- V
SW2
)/(I
SW1
-I
SW2
)
Min.
Typ.
0.2 0
6
15
160
20
Max.
Units
V
µA
ms
°C
°C
V
SS
=0V
C
SS
=0.1 µF
Conditions
BLOCK DIAGRAM
Fig. 2: XRP7665 Block Diagram
PIN ASSIGNMENT
Fig. 3: XRP7665 Pin Assignment
(SOIC - 8 Exposed Pad )
© 2013 Exar Corporation
3/ 12
Rev. 2.0. 1
X RP7 6 6 5
3 A 1 8 V S y n c h r o n o u s S t e p - D o w n Co n v e r t e r
PIN DESCRIPTION
Name
BS
Pin Number
1
Description
Bootstrap pin.
Connect a 0.01µF or greater
bootstrap capacitor between the BS pin and the SW pin.
The voltage across the bootstrap capacitor drives the internal high
- side power MOSFET.
Power input pin.
A capacitor should be connected between the IN pin and GND pin to keep the input
voltage constant.
Power switch output pin.
This pin is connected to the inductor and the bootstrap capacitor.
Ground signal pin.
Feedback pin.
An external resistor divider
connected to FB programs the output voltage.
If the
feedback pin exceeds 1.1V the over
- voltage protection will trigger. If the feedback
voltage drops below 0.3V the o
scillator frequency is lowered
to achieve short - circuit
protection.
Compensation pin.
This is the output of transconductance error amplifier and the input to the current
comparator. It is used to compensate the control loop. Connect an RC network form
this pin to GND.
Control input pin.
Forcing this pin above 2.7V enables the IC. Forcing this pin below
Soft - start control input pin.
Connect a capacitor from SS to GND to set the soft
the soft start period to 1
5ms. To disable the soft
Exposed Pad
Connect to GND through PCB .
0.75 V shuts down the
IN
SW
GND
2
3
4
FB
5
COMP
6
EN
7
SS
-
8
EP
- start period. A 0.1µF capaci
tor sets
- start feature, leave SS unconnected.
ORDERING INFORMATION
Part Number
XRP766 5ID BTR- F
XRP766 5EVB
Temperature
Range
Marking
Package
SOIC -8(EP)
Packing
Quantity
2.5 K/Tape & Reel
Note 1
RoHS Compliant
Halogen Free
Note 2
XRP766 5I
YYWWF
-
A
X
XRP766 5 Evaluation Board
; when applicable.
© 2013 Exar Corporation
4/ 12
Rev. 2.0. 1
X RP7 6 6 5
3 A 1 8 V S y n c h r o n o u s S t e p - D o w n Co n v e r t e r
TYPICAL PERFORMANCE
CHARACTERISTICS
T
J
= T
A
All data taken at V
IN
= 12 V, V
OUT
=3.3V,
Information section of this datasheet.
= 25°C, unless otherwise specified
- Schematic and BOM from Application
Fig. 4: Efficiency versus output current
Fig. 5: R
DSONH
versus case temperature
Fig. 6: R
DSONL
versus case temperature
Fig. 7: Feedback voltage versus case temperature
Fig. 8: Quiescent current versus case temperature
Fig. 9: Output voltage versus output current
© 2013 Exar Corporation
5/ 12
Rev. 2.0. 1
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