Quad Channel Digital Programmable Power Management System with Selectable DrMOS Output


The XR77129 is a quad channel Digital Pulse Width Modulated (DPWM) step down (buck) controller. An extremely wide 6V to 40V input voltage range allows for single supply operation from standard power rails.

With integrated FET gate drivers, two LDOs for standby power and a 105kHz to 1.23MHz independent channel to channel programmable constant operating frequency, the XR77129 reduces overall component count and solution footprint and optimizes conversion efficiencies. A selectable digital Pulse Frequency Mode (DPFM) capable of better than 80% efficiency at light current load and low operating current allow for portable and Energy Star compliant applications. Each XR77129 output channel is individually programmable as low as 0.6V with a resolution as fine as 2.5mV, and configurable for precise soft start and soft stop sequencing, including delay and ramp control.

The XR77129 operation is fully controlled via a SMBus-compliant I2C interface allowing for advanced local and/or remote reconfiguration, full performance monitoring and reporting as well as fault handling.

Built-in independent output Over-Voltage, Over-Temperature, Over-Current and Under-Voltage Lockout protections insure safe operation under abnormal operating conditions.

The XR77129 is offered in a RoHS compliant, "green"/halogen free 44-pin TQFN package.

Read More


  • Quad Channel Step-down Controller
    • Digital PWM 105kHz-1.23MHz Operation
    • Individual Channel Frequency Selection
    • Patented digital PFM with Ultrasonic mode
    • Patented Over Sampling Feedback
  • Pin Compatible to XRP7724 with added features
    • Selectable DrMOS drive capability
    • Additional GPIO configurability
    • Current limit fault options
    • Additional conditional fault options
    • Improved output voltage accuracy
  • 4.75V to 25V Input Voltage
    • 4.75V-5.5V and 5.5V-25V Input Ranges
    • 0.6V to 5.5V Output Voltage
  • SMBus Compliant - I2C Interface
    • Full Monitoring and Reporting
  • 3 x 15V Capable PSIO + 2 x GPIOs
  • Full Start/Stop Sequencing Support
  • Built-in Thermal, Over-Current, UVLO and Output Over-Voltage Protections
  • On Board 5V and 3.3V Standby LDOs
  • On Board Non-volatile Memory
  • Supported by PowerArchitect™ Design and Configuration Software


  • Automotive Infotainment
  • Industrial Control Systems
  • Audio systems
  • Automatic Test Equipment
  • Video Surveillance Systems

Design Tools

Symbols & Footprints
Evaluation Hardware and Software


Pkg Code Details Quantities Dimensions PDF
TQFN44 7x7
  • JEDEC Reference: MO-220
  • MSL Pb-Free: L3 @ 260ºC
  • MSL SnPb Eutectic: n/a
  • ThetaJA: 30.2ºC/W
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: 260
  • Quantity per Reel: 3000
  • Quantity per Tube: n/a
  • Quantity per Tray: 260
  • Reel Size (Dia. x Width x Pitch): 330 x 16 x 12
  • Tape & Reel Unit Orientation: Quadrant 1
  • Dimensions: mm
  • Length: 7.00
  • Width: 7.00
  • Thickness: 0.8
  • Lead Pitch: 0.50

Parts & Purchasing

Part Number Pkg Code RoHS Min Temp Max Temp Status Buy Now Order Samples
XR77129ELB-F TQFN44 7x7 Active
XR77129EVB-DEMO-1 Board Active
XR77129EVB-DEMO-1-KITA Kit Active
XR77XXEVB-XCM-V62 Board Active
Show obsolete parts
Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.

Quality Documents

Part NumberRoHSREACH
Additional Quality Documentation may be available, please contact customersupport@exar.com.
Distribution Date Description File
07/21/2017 Qualification of alternate assembly subcon, ANST. PCN 17-0626-01 ANST-1033.pdf
07/11/2017 Product Discontinuation Notification PDN_17-0623-01-1033.pdf

Frequently Asked Questions

Find the product page of the part that you want to get an evaluation board for and click on Parts & Purchasing. Example:


Find the icons under Buy Now or Order Samples:


Click on the Buy Now icon and see who has stock and click on the Buy button:


Alternatively, you can click on the Order Samples


If the icons are missing, then contact Customer Support.

The best way to determine this is to go to exar.com and type the part into the search function. At or near the top of the results you should see something that looks like

In this example, we looked for XRA1201. When you hover over it, it will turn grey and you can click anywhere in the grey box. This brings you to the product page. For example:


Click on Parts & Purchasing, highlighted in yellow above. The screen changes to:


Notice the status column and the “Show obsolete parts” link:


A legend tells you the definition of the different statuses. Click on the “Show obsolete parts” link to see EOL or OBS part numbers along with the Active part numbers:


Another method to find out if a part is OBS or EOL is to click on SUPPORT:


And then Product Change Notifications


Type the part into the search, and click on one of the part numbers from the drop down menu. Then you can look for the Product Discontinuation Notice, which generally is at the top of the list, for example:


If you see this, it tells you that this particular orderable part has been discontinued and when the last order date is, or was. If you click on the file, then you can view the notice we sent about this if you purchased the part in the recent past. It may also advise of a replacement part. When an orderable part first becomes discontinued, Product Discontinuation Notices are sent are sent to those who have purchased the parts in the recent past, if purchased directly, with a dated opportunity to place a last order.

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