4A, 18V, 500kHz, ACOT^® Step-Down Converter

RT6254A/RT6254B

The RT6254A/B is a high-performance, synchronous step-down DC-DC converter that can deliver up to 4A output current from a 4.5V to 18V input supply. The device integrates low R_DS(ON) power MOSFETs, accurate 0.6V reference and an integrated diode of bootstrap circuit to offer a very compact solution.
The RT6254A/B adopts Advanced Constant On-Time (ACOT^®) control architecture that provides ultrafast transient response and further reduces the external-component count. In steady states, the ACOT^® operates in nearly constant switching frequency over line, load and output voltage ranges and makes the EMI filter design easier.
The device offers Independent enable control input pin and power good indicator (TSOT-23-8 only) for easily sequence control. To control the inrush current during the startup, the device provides a fixed 1.5ms soft-start up. Fully protection features are also integrated in the device including the cycle-by-cycle current limit control, UVP, input UVLO and OTP.
The RT6254A/B is available in the TSOT-23-6 (FC) and TSOT-23-8 (FC) package.

Applications

Set Top Box
Portable TV
Access Point Router
DSL Modem
LCD TV

Key Spec.

	RT6254A	RT6254B
Status	Active	Active
Vin (min) (V)	4.5	4.5
Vin (max) (V)	18	18
Number of Outputs	1	1
Vout (min) (V)	0.6	0.6
Vout (max) (V)	5	5
Output Adj. Method	Resistor	Resistor
Iout (max) (A)	4	4
Current Limit (typ) (A)	6.2	6.2
Freq (typ) (kHz)	500	500
Ext Sync	No	No
Ron_HS (typ) (mOhm)	48	48
Ron_LS (typ) (mOhm)	25	25
Iq (typ) (mA)	0.115	0.115
Features	ACOT Control;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;OTP;PSM;Power Good;SCP;Stable with Ceramic Capacitor;UVP	ACOT Control;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;OTP;PSM;Power Good;SCP;Stable with Ceramic Capacitor;UVP
Package Type	TSOT-26(FC);TSOT-28(FC)	TSOT-26(FC);TSOT-28(FC)

Features

4.5V to 18V Input Voltage Range
4A Output Current
Constant-on-Time Mode to Enables Fast Transient Response
Low Output Ripple and Allows Ceramic Output Capacitor
500kHz Switching Frequency
High Efficient Internal Power MOSFET Switch Optimized for Lower Duty Cycle Applications
Integrated 48mΩ/25mΩ MOSFETs
Internal Soft-Start (1.5ms typ.)
Built-In UVP/OTP
Power Good Indicator (90%)
Input Under Voltage Lockout
TSOT-23-6 (FC) and TSOT-23-8 (FC) Packages