Step-Down DC/DC Converter

XC9267/68 Low Power 36V, 600mA, Buck DC/DC Converter

The XC9267/68 is a synchronous step-down DC/DC with P-Ch High Side Switch to ensure low voltage operation with 100% max duty ratio. It can operate from 3.0V~36.0V and deliver loads up to 600mA making it an ideal replacement for inefficient Linear Regulators used in many industrial applications.

Designed for very high efficiencies at low output loads, with low quiescent current, the XC9267/68 also works with Low ESR ceramic capacitors and comes with a choice of two switching frequencies, adjustable soft start and a power good output.

Available in the ultra-small USP-6C package, measuring only 2.0 x 1.8 x 0.6mm an extremely small DC/DC circuit can be implemented with a minimal number of external components.

The XC9268 includes a fold-back type current limit circuit and the IC will automatically resume normal operation as soon as the over-current condition disappears.

Key Features

Output Current 600mA
N-Ch 0.44Ω (typ)
P-Ch 1.12Ω (typ)
Input Voltage Range 3.0V ~ 36V (Ab. Max 40V)
Surge Voltage Protection 46V (≤400ms)
FB Voltage 0.75V±1.5%
Output Voltage Range 1.0V ~ 25.0V
Switching Frequency 1.2MHz or 2.2MHz
Quiescent Current 12.5µA (1.2MHz)
XC9267 Fixed PWM Control
XC9268 PWM/PFM Automatic Switching
Max Duty Cycle 100%
Protection Circuits Current Limit Fold-back Circuit
Short Circuit Protection
UVLO (2.7V)
Thermal Shutdown
Additional Features Adjustable Soft-start
Optional Power Good Output
Low ESR Ceramic capacitors
Op. Amb. Temperature -40℃ ~ +105℃
Package USP-6C or SOT89-5


Typical Application Circuit

Package Style



Wide 3V to 36V Input Range

Maximum input voltage is defined by the required output voltage, the TON(min) and the FOSC Two FOSC versions are available for optimised performance depending on application. The following diagrams illustrate the recommended VIN vs. VOUT operating conditions. Recommended inductor value is also tuned for different VOUT range.


FOSC= 1.2MHz:     Recommended for Industrial Applications


FOSC= 2.2MHz:     Recommended for Automotive Applications

(XD9267/68 - AEC-Q100 Version Coming Soon)


DC/DC External Coil Selection

External Coil Options

Torex recommends the following coils for use with the XC9267/68 series:

• Coilcraft XEL4030, dimensions: 4.0mm x 4.0mm

•  TDK CLF5030NIT, dimensions: 5.3mm x 5.0mm

Alternatively, different external coils can be also selected following the below guidelines.

How to choose a DC/DC external coil

Inductance Value

Please use only the DC/DC’s recommended inductor values. These values can be found from the above graphs according to VIN/VOUT conditions. Today’s Current Mode -type DC/DCs have a fixed phase compensation internally and non-recommended inductor value may cause unstable or double pulse operation.

Saturation Current

Please choose the coil saturation current (ISAT) versus DC/DC peak coil current (ICOIL,PEAK) following one of the two options below:


• ISAT > ICOIL,PEAK at the maximum IOUT rating of the DC/DC (even if such high currents are not needed)

Small Solution Size:

ISAT > ICOIL,PEAK at maximum IOUT of the DC/DC operating conditions (please note that in this case the current limit protection operation of the DC/DC cannot be guaranteed)


ICOIL,PEAK = ( 1/2 x (VIN - VOUT) x (VOUT/VIN x 1/fOSC) / L + IOUT ) / Efficiency

Voltage Rating

Ensure that coil voltage rating is ≥ 1.3 x VIN,MAX

Many coil datasheets do not specify the coil voltage but there is a chance that it may be < 20V. Therefore, please ask the coil manufacturer about the voltage rating when selecting a coil. As a guideline, ferrite core type coils have a higher rating than metal/multi-layer type coils.

Shielding & Thermal Dissipation

Please also take into account the necessary levels of shielding and thermal dissipation to fit with your system requirements


Want To Find Out More?

For more information on the XC9267 and the XC9268 series, please download the datasheets by clicking on the images below:



Fully populated evaluation boards also available from stock, please contact your local Torex representative for more details.