BD9610AMUV-E2 Datasheet, PDF (12/30 Pages) Rohm – 60V Synchronous Step-down Switching Regulator(Controller type)

BD9610AMUV
(5)External synchronization(SYNC)
This IC can be synchronized to an external clock through the SYNC pin for noise management and can be
used as a master IC to output clock through the CLKOUT terminal and as a slave IC to input clock through the SYNC
terminal for synchronizing some ICs
SYNC pin is connected to GND when not in use for this function.
GND
treatment
Master　IC
(Free running mode)
SYNC
CLKOUT
RT
RTSS
Slave　IC
（External synchronized mode）
CLK signal
proapagate wave
SYNC
RT
CLKOUT
RTSS
OPEN
treatment
Fig.27 A type of External synchronization circuit
Synchronization occurs on the series three rising edges of the SYNC signal. The clock frequency at the SYNC pin
replaces the master clock generated by the oscillator circuit. Pulling the SYNC pin low programs the BD961A0MUV
to freely run at the frequency programmed by RRT.
◆Input wave conditions into SYNC pin SYNC
The synchronization frequency should be in the range of -10% to +10% equal to its programmed free-run
frequency that is in the range of 50 to 500kHz. The input pulse should be more than 500ns and in the
range of 2.8V to 5.0V needed in H level . The special sequence against VCC or CTL is nothing.
Refer to RRT vs Frequency on the previous page when decided RT resistor fixed input signal frequency
into SYNC.
It recommended to decide if the BD9610AMUV is used at synchronizing function or not before start-up.
If it need to synchronize after start-up, please notice to the fluctuation of the Vout caused by the instability of
oscillation for a while. When the SYNC pin become open, the oscillator state is changed by detecting no eight series
pulses from synchronize mode to free-run mode. The BD9610AMUV freely run at the frequency programmed by RRT
slowly. It depends on the speed to conclude the RTSS voltage equal to 0.5V by charging or discharging CRTSS with
IRTSS (=5uA max.). The frequency changes with RTSS shift.
The RT voltage is fixed almost 0.5V at free-run mode. In synchronizing mode, the RT voltage adjusts freely to the
voltage between 0.25V and 1.0V for the oscillator to be able to output the synchronized frequency. The movement of
the RT voltage is smoothed by the CRTSS. When the capacitance of the CRTSS is too little, the frequency is
fluctuated. But the capacitance is too large, It takes long time to synchronize the frequency. It should be adjusted by
the behavior of your condition.
SYNC
Internal/
External
Synchronized
2.5V
①②③
Internal mode
External Mode (Synchronized CLK )
Internal mode
CT
Rtselect
（RT 1V/0.25V）
①②③④ ⑤ ⑥ ⑦ ⑧
2V
1.5V
The CT amplitude is automatically fitted to the amplitude of the internal mode.
RTSS
（≒RT)
The RTSS voltage is adjusted by (dis-)charging CRTSS(IRTSS=5uAmax.)
Fig.28 timing chart about External Mode
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TSZ22111・14・001
12/27
0.5V
TSZ02201-0Q1Q0AJ00010-1-2
24.OCT.2014 Rev.002