The RT2805A is a current mode asynchronous step-down converter that achieves excellent load and line regulation. Over a wide input voltage range from 5.5V to 36V and supports output current up to 5A. The Current mode operation provides fast transient response and eases loop stabilization. An adjustable soft-start reduces the stress on the input source at start up. In shutdown mode, the regulator draws only 25μA of supply current. The RT2805A requires a minimum number of readily available external components, providing a compact solution. The RT2805A provides protection functions inducing input under voltage lockout, cycle-by-cycle current limit, short circuit protection and thermal shutdown protection. The RT2805A is available in the SOP-8 (Exposed Pad) package.
•Distributive Power Systems
•Pre-regulator for Linear Regulators
•5A Output Current
•Wide Operating Input Range 5.5V to 36V
•Adjustable Output Voltage from 1.222V to 26V
•High Efficiency up to 90%
•Internal Compensation Minimizes External Parts Count
•110mΩ Internal Power MOSFET Switch
•25μA Shutdown Mode
•Fixed 500kHz Frequency
•Cycle-by-Cycle Current Limit
•Available In an SOP-8 (Exposed Pad) Package
•RoHS Compliant and Halogen Free
Please carefully inspect the EVB IC and external components, comparing them to the following Bill of Materials, to ensure that all components are installed and undamaged. If any components are missing or damaged during transportation, please contact the distributor or send e-mail to email@example.com
The EVB is provided with the test points and pin names listed in the table below.
Comment (expected waveforms or voltage levels on test points)
Input voltage range = 5.5V to 36V
Output voltage = 2.4V
Chip Enable Operation
The EN pin is externally pulled to High by adding a 100kΩ resistor (R4) from the VIN pin in this EVB setting. For another enable operation, the converter is turned on when the EN pin is higher than 1.4V and turned off when the EN pin is lower than 0.4V.
1. Connect input power (5.5V < VIN < 36V) and input ground to VIN and GND pins respectively.
2. Connect positive end and negative end of load to VOUT and GND of output pins respectively.
3. The output voltage of (VOUT) can be set by R1 and R2.
VOUT = VREF * (1 + R1 / R2)
where VREF = 1.222V (typ.)
Input Voltage Range
C3, C6, C11
6.8μH, 6A, ±20%, DCR = 23.3mΩ
10 x 10 x 3.8mm
R1, R2, R4
PCB Layout (1st layer)
PCB Layout (2nd layer)
PCB Layout (3rd layer)
PCB Layout (4th layer)