The KTB8400 is a precision and unique OptiCompTM buck-switching regulator with class-leading accuracy, transient response, efficiency, and solution size optimized for mobile and non-mobile application. It is I2C programmable for output voltages in the 0.6V to 3.345V range. It features soft-start and DVS with multiple programmable ramp rates. Versions with various default settings can be ordered. The features and performance make the KTB8400 suitable for a variety of applications including CPU/GPU core, DSP and baseband, DDR memory, VIO, and sensor/analog power.

The KTB8400 is available in RoHS and Green compliant 15-bump 1.340mm x 2.045mm x 0.6mm wafer-level chip-scale package (WLCSP).


  • 2.5 to 5.5V Input Voltage Range
  • Fixed Output Voltage = 1.3V
  • 0.6 to 3.345V Programmable Option for Vout
    • 6.25mV steps below 1.39375V
    • 15mV steps above 1.44V
  • 3.0A Output Current
  • ±1% Accuracy at TA = +25°C
    • ±2.5% over line/load/temp/setting
  • Fast Transient Response
  • Fast PLL Loop with accurate Switching frequency over load changes
  • Dynamic Voltage Scaling (DVS) with 8 ramp rates
  • 90% Peak Efficiency at Vout = 1.136V
  • 2.4MHz with Auto-Skip at light loads
    • Programmable forced-PWM mode
  • 46uA typ. No-Load Supply Current in Skip Mode
  • Tiny External Components
    • L = 330 or 470nH (2012 or 2016 metric size)
    • Cin = 10µF (0402), Cout = 2×22µF (2×0402)
  • Soft Start, Over-Current, Short-Circuit, Under/Over VIN, and Thermal Shutdown Protections
  • 1MHz I2C Interface
  • -40°C to 85°C Operating Temperature Range
  • 15-bump Pb-free WLCSP (0.4mm pitch)
    • 1.340 x 2.045mm (0.6mm height)
    • Pin/Register Compatible with FAN53527


  • CPU, GPU, AP, DSP, FPGA, I/O, XCVR Power
  • HDD, LPDDR3, LPDDR4 Memory Power
  • Tablets, Netbooks, Ultra-Books
  • Smartphones, Mobile Internet Devices, IoT
  • DSC, Drones, Gaming Consoles, Accessories

Packaging Information

Package Dimensions Bumps Package Code
WLCSP35-15 1.340mm x 2.045mm x 0.620mm 15 DAA


Vin (min)  Vin (max)  Switching Frequency (MHz) Max Current (A)
2.5V 5.5V 2.4 3.0

Technical Documentation

Description Documents Type
Package Outline DrawingWLCSP35-15 DAA PODPDF


Part Number Marking Default Output Voltage & Mode 7-bit I2C Slave Address Package
(VSEL = 1) (VSEL = 0)
KTB8400AEDAA-TR TRXXYYZZZZ 1.3V Forced-PWM 1.3V Auto-Skip 1100 000=0x60h WLCSP35-15
Purchase Options
Buy from Digi-Key
Buy from Mouser