XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
November 2016
Rev. 1A
Exar Corporation www.exar.com
48720 Kato Road, Fremont CA 94538, U SA Tel. +1 510 668-7000 – Fax. +1 510 668-7001
GENERAL DESCRIPTION
The XR76117 and XR76121 are synchronous step-down
regulators combining the controller, drivers, bootstrap
diode and MOSFETs in a single package for point-of-load
supplies. The XR76117 has a l oad current rating of 15A and
the XR76121 has a load current rating of 20A. A wide 5V to
22V input vo ltage range allows for s ingle supply operatio n
from ind us try stand ard 5V, 12V a nd 19.6V rails .
With a proprietary emulated current mode Constant On-
Time (COT) control scheme, the XR76117 and XR76121
provide extremely fast line and load transient response
using ceramic output capacitors. They require no loop
compensation, simplifying circuit implementation and
reducing overall component count. The control loop also
provides 0.1% load and 0.1% line regulation and maintains
constant operating frequency. A selectable power saving
mode, allows the user to operate in discontinuous mode
(DCM) at light current loads thereby significantly increasing
the converter ef fici en cy.
A host of prote c tion features , including over-curr e nt, over-
temperature, over-voltage, short-circuit, open feedback
detect and UVLO, help achieve safe operation under
abnor ma l operating conditions.
The XR76117/21 are available in a RoHS-compliant,
green/halogen-free space-saving QFN 5x6mm package.
EVALUATION BOARD MANUAL
FEATURES
• 15A and 20A Step Down Regulators
− 4.5V to 5.5V Low VIN Operation
− 5V to 22V Wide Single Input Voltage
− 3V to 22V operation with external 5V bias
− ≥0.6V Adjustable Output Voltage
• Proprietary Constant On-Time Control
− No L oop Compensation Required
− Ceramic Output Cap. Stable operatio n
− Programmable 70ns-1µs On-Time
− Constant 200kHz-1MHz Freq.
− Selectabl e CCM or CCM/ DCM O p erat ion
• Power-Good Flag with low impedance when power removed
• Precision Enable and Programmable Soft-start
Fig. 1: XR76121 Evaluation Board Schematics
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 2/8 Rev. 1A
PIN ASSIGNMENT
Fig. 2: XR76117/21 Pin Assignment
PIN DESCRIPTION
Name P in Numbe r Description
FB
1
Feedb ack input to feedback comparator.
FCCM
2
Forcing this p in log ic leve l high f or ces CC M oper ation
AGND
3
Signal ground for control circ uitry. Connect to AGND Pad with a short trace .
4
TON
5
Constant on-time programming pin. Connect with a resistor to AGND.
ILIM
6
Over-curre nt prote c ti o n programming. Connect with a resistor to SW.
PGOOD
7
Power-goo d o utp ut. Open drain to AGND . Low Z when IC unpowered.
VSNS
8
Sense pin for output OVP and open FB.
VIN
9
Supply inp ut for the regula to r’s LDO. Normally connec te d to PVI N.
VCC
10
The output of reg ulator’s LDO. It requir es a 4.7uF VCC bypass c apac itor . For operation
using a 5V rail, VCC sho ul d be tied to VIN.
PGND
11
Ground of the power s tage. Inter nall y c onnected to source of the low-side MOSFET.
SW
12
Switch Nod e . Inter nally it connects source of the hig h-sid e MOSF E T to drain of the low -
side MOSFET.
PVIN
13
Input voltage for power stage. Internally co nne c ted to drain of the high-side MOSFET.
BST
14
High-side dr iver supply pin. Connect a 0.1 uF boots trap capacitor between BST and SW.
EN
15
Precis ion enable pin. Pulling this pin above 2V will enable the regulator.
SS
16
Soft-Start pin. Conne c t an external capac itor between SS and AGND to program the
soft-start rate based on the 10uA inter nal so urce curr e nt.
AGN D P AD
17
Signal ground for control circ uitry.
ORDERING INFORMATION
Refer to XR76117/21 datasheet and/or www.exar.com for exact and up to date ordering information.
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 3/8 Rev. 1A
USING THE EVALUATION BOARD
POWERING UP
Connect the VIN+/VIN- with short/thick leads to power
supply. Use test pins T3 and T4 to monitor VIN+ and
VIN- respectively. Connect VOUT+/VOUT- with
short/thick leads to an electronic load. Use test pins T1
and T2 to monitor VOUT+ and VOUT- respectively.
Apply 12V using the power supply. The XR76117/21
EVB should power up and regulate the output at 1.8V.
Input voltage range is from 5V to 22V. Maximum rated
current for XR76117/21 is 15A and 20A respectively.
JUMPER J1
If the jumper is set to CCM position the Regulator will
operate in “forced CCM”. Note that, as explained in the
datasheet, after power up the regulator will operate in
DCM until a sufficient load is applied to transition the
Regulator to CCM. Once the Regulator transitions to
CCM it will continue operating in CCM regardless of
load magnitude.
If the Jumper is set to DCM/CCM position the
Regulator will operate in DCM at light load.
OPERATION FROM A 5V RAIL (VIN=4.5V-5.5V)
For operation from a 5V rail it is recommended to tie
output of the LDO to VIN by populating R5VIN with a
0Ω resistor. This enhances the operation of the drivers
at VIN<5V. Please remember to remove R5VIN for
operation at higher VIN.
PROGRAMMING THE OUTPUT VOLTAGE
VOUT can be programmed by changing RFB1
according to:
1=2 ×
0.6 1
Where RFB2 has a nominal value of 2kΩ.
RON must be set correspondingly, as explained in the
datasheet, in order to get the desired switching
frequency.
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 4/8 Rev. 1A
EVALUATION BOARD SCHEMATICS
XR76121 EVB Schematics
XR76117 EVB Schematics
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 5/8 Rev. 1A
XR76121EVB BILL OF MATERIAL
XR76117EVB BILL OF MATERIAL
Reference Qty. Manufacturer Manufacturer Size Component
Designator Part Number
PCB 1Exar 146-6725-02 XR76121 Evaluati on B oard
U1 1Exar XR76121EL-F 5mmX6mm Step- Down COT Regulator
L1 1VISHAY/DALE IHLP5050FDERR40M01 12.9x13.2mm Power Induc t or 0.4uH, 44A, 1m Ohm
C5,C6,C7,C8 4MURATA GRM31CR61E226KE15L 1206 CERAMI C CA P. 22uF, 25V, X5R, 10%
C26,C27,C28,C29,C30 5MURATA GRM31CR60J107ME39K 1206 CERAMI C CA P. 100uF , 6. 3V, X5R, 20%
CBST,CIN,C1,C2,C31-C34 8MURATA GRM155R71H104KE14D
0402 CERAMI C CA P. 0.1uF, 50V, X7R, 10%
CVCC 1MURATA GRM188R61A475KE15D
0603 CERAMI C CER , 4. 7uF , 10V, X 5R, 10%
CSS 1MURATA G RM155R71H473KE14D
0402 CERAMI C CA P , 47nF , 50V , X7R, 10%
CFF 1MURATA GRM155R71H471KA01D
0402 CERAMI C CA P. , 470PF, 50V, X7R, 10%
RFB1,RSENS1 2PANASONIC
ERJ- 2RK F 4021X 0402 Resi stor 4.02K Ohm, 1/10W,1% ,S MD
RFB2,RSENS2 2PANASONIC
ERJ- 2RK F 2001X 0402 Resi stor 2.0K Ohm, 1/10W,1% ,S MD
RVIN,RBST,RBODE 3PANASONIC
ERJ- 2GE0R00X 0402 Resi stor 0.00 Ohm , J umper, 1/10W, SMD
RPGOOD, REN1 2PANASONIC
ER J-2RKF1002X 0402 Resi stor 10.0K Ohm, 1/10W,1% ,S MD
REN2 1PANASONIC
ERJ- 2RK F 3831X 0402 Resi stor 3.83K Ohm, 1/10W,1% ,S MD
RLIM 1PANASONIC
ERJ- 2RK F 1821X 0402 Resi stor 1.82K Ohm, 1/10W,1% ,S MD
RFF 1PANASONIC
ERJ- 2RK F 4020X 0402 Resi stor 402 Ohm, 1/10W, 1% ,SMD
RON 1PANASONIC
ERJ- 2RK F 6191X 0402 Resi stor 6.19K Ohm, 1/10W,1% ,S MD
LIN 1VISHAY/DALE
CRCW12100000Z 0EAHP 2010 Resi stor 0.00 Ohm , J umper, 3/4W, SMD
T1-T4,VCC,PGOOD,SS,EN,AGND 9Wurth Elek tronik 61300111121 2.54mm H eader 1 pin
J1 1Wurt h Elekt roni k 61300311121 2.54mm H eader 3 pin
J2 1Wurt h Elekt roni k 61300211121 2.54mm H eader 2 pin
VIN-, VIN+, VOUT-, VOUT+ 4Wurt h Elekt roni k 7471287 M ountin Tab WA-M TAB
J1-Jumper 1Wurth Elekt roni k 60900213421 2.54mm Header Jumper
Reference Qty. Manufacturer Manufacturer Size Component
Designator Part Number
PCB 1Exar 146-6725-02 XR76117 Evaluati on B oard
U1 1Exar XR76117EL-F 5mmX6mm Step- Down COT Regulator
L1 1VISHAY/DALE IHLP4040DZERR36M01 10.3x10.92mm Power Induc t or 0.36uH, 31.5A, 1.3mOhm
C5,C6,C7,C8 4MURATA GRM31CR61E226KE15L 1206 CERAMI C CA P. 22uF, 25V, X5R, 10%
C26,C27,C28 3MURATA GRM31CR60J107ME39K 1206 CER AMI C CAP. 100uF, 6. 3V, X5R, 20%
CBST,CIN,C1,C2,C31-C34 8MURATA GRM155R71H104KE14D
0402 CERAMI C CA P. 0.1uF, 50V, X7R, 10%
CVCC 1MURATA GRM188R61A475KE15D
0603 CERAMI C CER , 4. 7uF , 10V, X 5R, 10%
CSS 1MURATA G RM155R71H473KE14D
0402 CERAMI C CA P , 47nF , 50V , X7R, 10%
CFF 1MURATA GRM155R71H471KA01D
0402 CERAMI C CA P. , 470PF, 50V, X7R, 10%
RFB1,RSENS1 2PANASONIC
ERJ- 2RK F 4021X 0402 Resi stor 4.02K Ohm, 1/10W,1% ,S MD
RFB2,RSENS2 2PANASONIC
ERJ- 2RK F 2001X 0402 Resi stor 2.0K Ohm, 1/10W,1% ,S MD
RVIN,RBST,RBODE 3PANASONIC
ERJ- 2GE0R00X 0402 Resi stor 0.00 Ohm , J umper, 1/10W, SMD
RPGOOD, REN1 2PANASONIC
ER J-2RKF1002X 0402 Resi stor 10.0K Ohm, 1/10W,1% ,S MD
REN2 1PANASONIC
ERJ- 2RK F 3831X 0402 Resi stor 3.83K Ohm, 1/10W,1% ,S MD
RLIM 1PANASONIC
ERJ- 2RK F 3161X 0402 Resi stor 3.16K Ohm, 1/10W,1% ,S MD
RFF 1PANASONIC
ERJ- 2RK F 4020X 0402 Resi stor 402 Ohm, 1/10W, 1% ,SMD
RON 1PANASONIC
ERJ- 2RK F 6191X 0402 Resi stor 6.19K Ohm, 1/10W,1% ,S MD
LIN 1VISHAY/DALE
CRCW12100000Z 0EAHP 2010 Resi stor 0.00 Ohm , J umper, 3/4W, SMD
T1-T4,VCC,PGOOD,SS,EN,AGND 9Wurth Elek tronik 61300111121 2.54mm H eader 1 pin
J1 1Wurt h Elekt roni k 61300311121 2.54mm H eader 3 pin
J2 1Wurt h Elekt roni k 61300211121 2.54mm H eader 2 pin
VIN-, VIN+, VOUT-, VOUT+ 4Wurt h Elekt roni k 7471287 M ountin Tab WA-M TAB
J1-Jumper 1Wurth Elekt roni k 60900213421 2.54mm Header Jumper
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 6/8 Rev. 1A
EVALUATION BOARD LAYOUT
Fig. 3: Assembly Top
Fig. 4: Assembly Bottom
Fig. 5: Top
Fig. 6: Bottom
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 7/8 Rev. 1A
Fig. 7: Layer 2
Fig. 8: Layer 3
Fig. 9: Layer 4
Fig. 10: Layer 5
XR76117/21
PowerBlox 15A and 20A Synchronous Step Down COT
Regulator
© 2016 Exar Cor por ation 8/8 Rev. 1A
DOCUMENT REVISION HISTORY
Revision Date Description
1A 11/16 Initial release of document
BOARD REVISION HISTORY
Board Revision Date Description
REV 2.0
2/16
Initial release of evaluation board
FOR FURTHER ASSISTANCE
Email: customersupport@exar.com
powertechsupport@exar.com
Exar Technical Documentation: http://www.exar.com/TechDoc/
EXAR CORPORATION
HEADQUARTERS AND SALES OFFICES
48720 Kato Road
Fremont, CA 94538 – USA
Tel.: +1 (510) 668-7000
Fax: +1 (510) 668-7030
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 herein 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.
