Dear BU,
Could you pls check whether the TPS61178 couldn't achieve sync via the FPGA input 500KHZ. Customer test the SW PIN and FREQ PIN.
The Yellow waveform is CLK in FREQ PIN is 500Khz.
The Blue waveform is FREQ PIN is just 800K~1Mhz.
The circuit design of the TPS61178 is based on the design in TIDA-010057
Device pin1 is connected to a 360K resistor
The synchronous CLK signal (500KHz, 3.3V, 50% duty cycle) was input from the C243 position, but when measuring the SW pin of the device (pin7), it was found that the operating waveform frequency of the device was jitter around 340-390 KHZ.
The Yellow waveform is SW PIN.
The Blue waveform is CLK in FREQ PIN is 500Khz.
1, try to disconnect C243, the device switching frequency can be measured at about 495KHz
The Yellow waveform is SW PIN.
2, restore C243, disconnect the resistance at the R139 position, the device switching frequency is more than 900 KHz, can not be synchronized to the input 500KHz
The C243 is changed to direct connection, and the D17 and R139 are removed - this state has been tested, and it is also unable to synchronize the operating frequency of the TPS61178 device to 500KHz
The 500KHz sync clock of the FPGA output could be measured on the input side of the C243 position, but the 61178 device was never able to synchronize to this frequency.
Does the TPS61178 not support external synchronization and can only be automatically PFM performed by the IC?
Can TPS611781 support external synchronization?
