Datasheet

t – Time
V
HDRV
V
SYNC
Master Mode (SYNC as an output pin)
t – Time
V
HDRV
V
SYNC
Slave 180 Mode (SYNC as an input pin)
t – Time
V
HDRV
V
SYNC
Slave 0 Mode (SYNC as an input pin)
UDG-09206
TPS40170
www.ti.com SLUS970A –MARCH 2011–REVISED NOVEMBER 2013
Frequency Synchronization
The TPS40170 has three modes.
• Master mode: In this mode the master/slave selector pin, (M/S) is connected to VIN. The SYNC pin emits a
stream of pulses at the same frequency as the PWM switching frequency. The pulse stream at the SYNC pin
is of 50% duty cycle and the same amplitude as V
VBP
. Also, the falling edge of the voltage on SYNC pin is
synchronized with the rising edge of the HDRV.
• Slave-180° mode: In this mode the M/S pin is connected to GND. The SYNC pin of the TPS40170 accepts a
synchronization clock signal, and the HDRV is synchronized with the rising edge of the incoming
synchronization clock.
• Slave-0° mode: In this mode, the M/S pin is left open. The SYNC pin of the TPS40170 accepts a
synchronization clock signal, and the HDRV is synchronized with the falling edge of the incoming
synchronization clock.
The two slave modes can be synchronized to an external clock through the SYNC pin. They are shown in
Figure 24. The synchronization frequency should be within ±30% of its programmed free running frequency.
Figure 24. Frequency Synchronization Waveforms in Different Modes
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