Exar XRP7664-65-74-75 User manual

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
August 2014 Rev. 2
.0.0
Exar Corporation www.exar.com
48720 Kato Road, remont CA 94538, USA Tel. [phone] – ax. [phone]
GENERAL DESCRIPTION
The EXAR XRP76XX Evaluation kit is a fully
assembled and tested surface-mount PCB that
demonstrates the XRP7664, XRP7665,
XRP7674 and XRP7675 synchronous buck
regulators. The current-mode switching
regulator generates a preset 3.3V output with
a load of up to 2A (XRP7664, XRP7674) and
3A (XRP7665, XRP7675).
The EVB kit requires a single input voltage VIN
source if EN is tied to VIN via jumper J1
(default setting as supplied from EXAR). If J1
is set to EN=EXT position then a logic-level
signal is required at EN pin in order to turn the
regulator on and off.
STANDARD CONFIGURATION
The XRP76XXEVB evaluation board is
configured to operate under the following
conditions and parameters:
•Input voltage range: 4.5V - 18V
•Output voltage range: 3.3V
•Output current/load range: 0 – 2A/3A
EVALUATION BOARD MANUAL
FEATURES
•2A/3A Continuous Output Current
•4.5V to 18V Wide Input Vo tage
•PWM Current-Mode Contro
•Adjustab e Output Vo tage
−2% Accuracy
•Programmab e Soft-Start and Enab e
Function
•Constant frequency (XRP7664-65)
•Light- oad efficiency (XRP7674-75)
•Bui t-in Therma , Over Current, UVLO
and Output Over-Vo tage Protections
•RoHS Comp iant “Green”/Ha ogen Free
8-Pin Exposed Pad SOIC Package
EVALUATION BOARD SCHEMATICS
ig. 1: XRP76XX Evaluation Board Schematics
C4
22uF
CSS 0.1uFCBS 10nF
CC
nF
RC
k
CC1
DNP
R4 100k
J1
1 2 3
FB
C2
DNP C3
22uF
GND
VIN
VOUT
GND
EN
1
SW
1
U1
XRP76XX
BS
1
IN
2
SW
3
GND
4FB 5
COMP 6
EN 7
SS 8
L1
uH R1
26.1k
R2
10k
C1
uF
EN=EXTEN=VIN
SW
SW
FB

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 2/8 Rev. 2.0.0
PIN ASSIGNMENT
ig. 2: XRP7664-65-74-75 Pin Assignment, Exposed Pad applicable to XRP7665 and XRP7675
PIN DESCRIPTION
Name Pin Number Description
BS 1
Bootstrap pin. Connect a 0.01u or larger bootstrap capacitor between the BS pin and
the SW pin. The voltage across the bootstrap capacitor drives the internal high-side
power MOS ET.
IN 2 Supply input pin. A capacitor should be connected between the IN pin and GND pin to
keep the input voltage constant.
SW 3 Power switch output pin. This pin is connected to the inductor and the bootstrap
capacitor.
GND 4 Ground pin.
B 5
eedback pin. An external resistor divider connected to B 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 oscillator frequency is lowered to short-circuit
protection.
COMP 6
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.
EN 7
Control input pin.
Drive EN high/low in order to turn on/off the regulator. When the IC is in shutdown
mode all functions are disabled to decrease the supply current below 0.1µA nominal.
SS 8
Soft-start control input pin. Connect a capacitor from SS to GND to set the soft-start
period. A 0.1µ capacitor sets the soft start period to 15ms. To disable the soft-start
feature, leave SS unconnected.
ORDERING INFORMATION
Refer to XRP7664-65-74-75’s datasheet and/or www.exar.com for exact and up to date ordering
information.

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 3/8 Rev. 2.0.0
USING THE EVALUATION BOARD
I NITIAL S ETUP
Set the input supply to 12V and connect it to
VIN and GND connectors on the left side of the
evaluation board. Connect the load to the
VOUT and GND connectors at the right side of
the board. Check to make sure that jumper J1
is set to the left side (position marked
EN=VIN). The board will power up and
regulate the output at 3.3V upon turning on
the input supply. The XRP76XX should provide
nominal efficiency equal to figure 4 of the
datasheet.
J UMPER J1 FUNCTION
Jumper J1 can be used to either connect EN to
VIN or allow an independent logic-level control
signal to be applied to EN. The board is
supplied from EXAR with jumper set at left-
side (position marked EN=VIN). This allows for
automatic startup of the XRP76XX regulator
when VIN is applied.
SETTING THE OUTPUT VOLTAGE
Use an external resistor divider to set the
output voltage. Program the output voltage
from:
1  2  

0.925 1
Where:
R1 is the resistor between V
OUT
and B
R2 is the resistor between B and GND
(nominally 10kΩ)
0.925V is the nominal feedback voltage.

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 4/8 Rev. 2.0.0
EVALUATION BOARD SCHEMATICS
C4
22uF
CSS 0.1uFCBS 10nF
CC
nF
RC
k
CC1
DNP
R4 100k
J1
1 2 3
FB
C2
DNP C3
22uF
GND
VIN
VOUT
GND
EN
1
SW
1
U1
XRP76XX
BS
1
IN
2
SW
3
GND
4FB 5
COMP 6
EN 7
SS 8
L1
uH R1
26.1k
R2
10k
C1
uF
EN=EXTEN=VIN
SW
SW
FB

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 5/8 Rev. 2.0.0
XRP7664 BILL OF MATERIAL
XRP7665 BILL Of MATERIAL
Reference Qty. Manufacturer Part Number Size Component
PCB 1 Exar XRP7664EVB 1.3"x2" XRP7664 Evaluation kit
U1 1 Exar XRP7664 SO-8 2A Buck regulator
L1 1 COOPER-Bussmann DR74-100R 7.6x7.6mm 10uH shielded inductor
C1 1 Murata Corp. GRM32DR61E106KA12L 1210 CER CAP 10u , 25V, X5R
C3, C4 2 Murata Corp. GRM31CR61A226ME19L 1206 CER CAP 22u , 10V, X5R
CBS 1 Murata Corp. GRM188R71H103KA01D 0603 CAR CEP 10000p , X7R, 50V
CC 1 Murata Corp. GRM188R71H332KA01D 0603 CAP CER 3300p , X7R, 50V
CSS 1 Murata Corp. GRM188R71H104KA57D 0603 CAP CER 0.1u , X7R, 50V
R1 1 Panasonic ERJ-3EK 2612V 0603 Resistor 26.1K Ohm, 1%
R2 1 Panasonic ERJ-3EK 1002V 0603 Resistor 10K Ohm, 1%
RC 1 Panasonic ERJ-3EK 5621V 0603 Resistor 5.62K Ohm, 1%
R4 1 Panasonic ERJ-3EK 1003V 0603 Resistor 100K Ohm, 1%
J1 1 Wurth Elektronik 61304011121 Conn. Header 0.1" 3POS
J1(JUMPER) 1 Wurth Elektronik 609002115121 CONN JUMPER SHORT.
VIN, VOUT, GND, EN, SW 6 Vector Electronic K24C/M .042 Dia Test Point Post
Reference Qty. Manufacturer Part Number Size Component
PCB 1 Exar XRP7665EVB 1.3"x2" XRP7665 Evaluation kit
U1 1 Exar XRP7665 PSO-8 3A Buck Regulator
L1 1 Wurth Elektronik 744314850 7x7x5mm 8.5uH shielded inductor
C1 1 Murata Corp. GRM32ER61E226KE15L 1210 CER CAP 22u , 25V, X5R
C3, C4 2 Murata Corp. GRM31CR61A226KE19L 1206 CER CAP 22u , 10V, X5R
CBS 1 Murata Corp. GRM188R71H103KA01D 603 CAP CEP 10000p , X7R, 50V
CC 1 Murata Corp. GRM188R71H392KA01D 603 CAP CER 3900p , X7R, 50V
CSS 1 Murata Corp. GRM188R71H104KA57D 603 CAP CER 0.1u , X7R, 50V
R1 1 Panasonic ERJ-3EK 2612V 603 Resistor 26.1k Ohm, 1%
R2 1 Panasonic ERJ-3EK 1002V 603 Resistor 10k Ohm, 1%
RC 1 Panasonic ERJ-3EK 6821V 603 Resistor 6.81k Ohm, 1%
R4 1 Panasonic ERJ-3EK 1003V 603 Resistor 100k Ohm, 1%
J1 1 Wurth Elektronik 61304011121 Conn. Header 0.1" 3POS
J1(JUMPER) 1 Wurth Elektronik 609002115121 CONN JUMPER SHORT.
VIN, VOUT, GND, EN, SW 6 Vector Electronic K24C/M .042 Dia Test Point Post

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 6/8 Rev. 2.0.0
XRP7674 BILL OF MATERIAL
XRP7675 BILL Of MATERIAL
Reference Qty. Manufacturer Part Number Size Component
PCB 1 Exar XRP7674EVB 1.3"x2" XRP7674 Evaluation kit
U1 1 Exar XRP7674 SO-8 2A Buck Regulator, light-load efficient
L1 1 COOPER-Bussmann DR74-100R 7.6x7.6mm 10uH shielded inductor
C1 1 Murata Corp. GRM32DR61E106KA12L 1210 CER CAP 10u , 25V, X5R
C3, C4 2 Murata Corp. GRM31CR61A226ME19L 1206 CER CAP 22u , 10V, X5R
CBS 1 Murata Corp. GRM188R71H103KA01D 0603 CAR CEP 10000p , X7R, 50V
CC 1 Murata Corp. GRM188R71H472KA01D 0603 CAP CER4700p , X7R, 50V
CSS 1 Murata Corp. GRM188R71H104KA57D 0603 CAP CER 0.1u , X7R, 50V
R1 1 Vishay/Dale CRCW060326K1 KEA 0603 Resistor 26.1K Ohm, 1%
R2 1 Vishay/Dale CRCW060310K0 KEA 0603 Resistor 10K Ohm, 1%
RC 1 Vishay/Dale CRCW060313K0 KEA 0603 Resistor 13K Ohm, 1%
R4 1 Vishay/Dale CRCW0603100K KEA 0603 Resistor 100K Ohm, 1%
J1 1 Wurth Elektronik 61304011121 Conn. Header 0.1" 3POS
J1(JUMPER) 1 Wurth Elektronik 609002115121 CONN JUMPER SHORT.
VIN, VOUT, GND, EN, SW 6 Vector Electronic K24C/M .042 Dia Test Point Post
Reference Qty. Manufacturer Part Number Size Component
PCB 1 Exar XRP7675EVB 1.3"x2" XRP7675 Evaluation kit
U1 1 Exar XRP7675EVB PSO-8 3A Buck Regulator, Light-Load efficient
L1 1 Wurth Elektronik 744314850 7x7x5mm 8.5uH shielded inductor
C1 1 Murata Corp. GRM32ER61E226KE15L 1210 CER CAP 22u , 25V, X5R
C3, C4 2 Murata Corp. GRM31CR61A226ME19L 1206 CER CAP 22u , 10V, X5R
CBS 1 Murata Corp. GRM188R71H103KA01D 603 CAR CEP 10000p , X7R, 50V
CC 1 Murata Corp. GRM188R71H332KA01D 603 CAP CER 3300p , X7R, 50V
CSS 1 Murata Corp. GRM188R71H104KA57D 603 CAP CER 0.1u , X7R, 50V
R1 1 Vishay/Dale CRCW060326K1 KEA 603 Resistor 26.1K Ohm, 1%
R2 1 Vishay/Dale CRCW060310K0 KEA 603 Resistor 10K Ohm, 1%
RC 1 Vishay/Dale CRCW060313K0 KEA 603 Resistor 13K Ohm, 1%
R4 1 Vishay/Dale CRCW0603100K KEA 603 Resistor 100K Ohm, 1%
J1 1 Wurth Elektronik 61304011121 Conn. Header 0.1" 3POS
J1(JUMPER) 1 Wurth Elektronik 609002115121 CONN JUMPER SHORT.
VIN, VOUT, GND, EN, SW 6 Vector Electronic K24C/M .042 Dia Test Point Post

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 7/8 Rev. 2.0.0
EVALUATION BOARD LAYOUT
ig. 3: Component Placement – Top Side
ig. 4: Layout – Bottom Side

XRP7664-65-74-
75
2A/3A 18V Synchronous Step-
Down Regu ator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-
75)
© 2014 Exar Corporation 8/8 Rev. 2.0.0
DOCUMENT REVISION HISTORY
Revision Date Description
1.0.0 10/29/10 Initial release of XRP7664-65 EVB Manual
1.0.0 03/22/13 Initial release of XRP7674-75 EVB Manual
2.0.0 08/19/14 Initial release of combined XRP7664-65-74-75 EVB Manual
BOARD REVISION HISTORY
Board Revision Date Description
146-6688-01 10/29/10 Initial release of evaluation board XRP7664-65
146-6688-04 03/22/13 Initial release of evaluation board XRP7674-75
146-6688-05 08/19/14 Initial release of combined XRP7664-65-74-75 EVB
FOR FURTHER ASSISTANCE
Email: [e-mail]
[e-mail]
Exar Technical Documentation: http://www.exar.com/TechDoc/
E XAR C ORPORATION
H EADQUARTERS AND S ALES O FFICES
48720 Kato Road
remont, CA 94538 – USA
Tel.: [phone]
ax: [phone]
www.exar.com
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve
design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein,
conveys no license under any patent or other right, and makes no representation that the circuits are free of patent
infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a
user’s specific application. While the information in this publication has been carefully checked; no responsibility, however,
is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or
malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its
safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in
writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all
such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances.
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.