2.5MHz, Synchronous Boost Regulator with Bypass Mode


Update Alert Share

The RT4805B allows systems to take advantage of new battery chemistries that can supply significant energy when the battery voltage is lower than the required voltage for system power ICs. By combining built-in power transistors, synchronous rectification, and low supply current; this IC provides a compact solution for systems using advanced Li-Ion battery chemistries.

The RT4805B is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery, even when the battery voltage is below system minimum. In boost mode, output voltage regulation is guaranteed to a maximum load current of 2A. Quiescent current in Shutdown Mode is less than 1μA, which maximizes battery life. The regulator transitions smoothly between Bypass and normal Boost Mode. The device can be forced into Bypass Mode to reduce quiescent current.

The RT4805B is available in the WL-CSP-16B 1.67x1.67 (BSC) package.


  • Single-Cell Li-Ion, LiFePO4 Smart-Phones or Tablet
  • 2.5G/3G/4G Mini-Module Data Cards
Key Spec.
Status Active
Vin (min) (V) 1.8
Vin (max) (V) 5
Vout (min) (V) 2.85
Vout (max) (V) 4.4
Output Adj. Method Digital
Iq (typ) (mA) 0.055
SW Current Limit (typ) (A) 4
Freq (typ) (kHz) 2500
Freq (min) (kHz) 2000
Freq (max) (kHz) 3000
Ron (typ) (Ohm) 0.04;0.06
Features Adjustable Current Limit;Current Mode Control;Cycle-by-Cycle Current Limit;Enable Input;Internal Compensation;OCP;OVP;Power Good;UVP
Package Type WL-CSP1.67x1.67-16(BSC)
  • 4 Few External Components : 0.47μH Inductor and 0603 Case Size Input and Output Capacitors
  • Input Voltage Range : 1.8V to 5V
  • Output Range from 2.85V to 4.4V
    ► VSEL = L 3.15V
    ► VSEL = H 3.6V
  • Maximum Continuous Load Current : 2A at VIN > 2.65V Boosting VOUT to 3.35V
  • Up to 96% Efficient
  • True Bypass Operation when VIN > Target VOUT
  • Internal Synchronous Rectifier
  • True Load Disconnect when Shut Down
  • Forced Bypass Mode
  • VSEL Control to Optimize Target VOUT
  • Short-Circuit Protection
  • I2C Controlled Interface
  • Ultra Low Operating Quiescent Current
  • Small WL-CSP 16B Package
TitleLast UpdateShareDownload
2.5MHz, Synchronous Boost Regulator with Bypass Mode2017/02/23
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT4805BWSCWL-CSP1.67x1.67-16(BSC)3000 Request Buy from Distributor