BD9D321EFJ Datasheet, PDF (11/28 Pages) Rohm – 4.5V to 18V Input, 3.0A Integrated MOSFET 1ch Synchronous Buck DC/DC Converter

BD9D321EFJ
Datasheet
Function Explanations
1 Basic Operation
1-1 Constant On Time Control
BD9D321EFJ is a single synchronous buck switching regulator employing a constant on-time control system.
It controls the on-time by using the duty ratio of VOUT /VIN inside IC so that a switching frequency becomes 700 kHz.
Therefore it runs with the frequency of 700 kHz under the constant on-time decided with VOUT / VIN.
1-2 SLLM^TM Control
BD9D321EFJ utilizes switching operation in PWM (Pulse Width Modulation) mode for heavier load, while it utilizes
SLLM (Simple Light Load Mode) control for lighter load to improve efficiency.
① SLLM^TM Control
② PWM Control
Output Current IOUT[A]
Figure 21. Efficiency (SLLM^TM Control and PWM Control)
①SLLM^TM Control
VOUT
20mV/div
SW
5V/div
②PWM Control
VOUT
20mV/div
SW
5V/div
10µsec/div
Figure 22. SW Waveform (①SLLM^TM control)
(VIN = 12V, VOUT = 1.8V, IOUT = 30mA)
1µsec/div
Figure 23. SW Waveform (②PWM control)
(VIN = 12V, VOUT = 1.8V, IOUT = 3A)
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TSZ22111•15•001
11/25
TSZ02201-0J3J0AC00490-1-2
07.Aug.2013 Rev.001