Part Number: TPS65070
I'm using the TPS65070 as Power-Manager of an IIoT-System. As power-supply I use LiPo or/and AC. After booting the TSP EN_DCDC1 is high and in the CON_CTRL1-Register there is the default setting “01111111” This means after pulling down PB_IN the DCDC1-Converter should start when EN_DCDC1 is high. (While pulling down PB_IN, POWER_ON is set high) The first time after attaching a power supply the TCP boots properly and the DCDC1 supplies the configured voltage. After shutting down with pulling POWER_ON to low a reboot of the TPS doesn't start the DCDC1. How can I fix this problem? Yours sincerely,
In reply to Gordon Varney:
hi, please find below feedback from customer:
I will describe the problem again. I use the TPS65070 as power manager for an IIOT-System. Only one of the three Step-Down Converters is used (DCDC1). For the chip the default settings of power sequencing is 011, this means that DCDC1 should be enabled by pulling EN_DCDC1 high. When AC or USB are used as power supply, pulling PB_IN to GND, POWER_ON to high and EN_DCDC1 to high should start the DCDC1. But this doesn’t happen. DCDC1 is not starting. Only when a battery is used as single power supply this sequence leads to a starting DCDC1, but only for the first time. By a second starting sequence, the same problem occurs as for AC or USB power supplies.
Can you tell me why DCDC1 does not start, even when all starting conditions are set.
In reply to Kamal Najmi:
Can you send me a copy of your schematic for review. As you describe it the DC-DC1 should be starting. Feel free to send the schematic directly to me.
I have been looking at your schematics. I don't see anything obvious, but I do have a few things to check. I colored them blue below.
To start up each converter independently, the device has a separate enable pin for each of the DC-DC
converters. In order to enable any converter with its enable pins, the TPS6507x devices need to be in ON-state
by pulling PB_IN=LOW or POWER_ON=HIGH. The sequencing option programmed needs to be DCDC_SQ[2..0]
If EN_DCDC1, EN_DCDC2, EN_DCDC3 are set to high, the corresponding converter starts up with soft start as
Pulling the enable pin low forces the device into shutdown, with a shutdown quiescent current as defined in the
electrical characteristics. In this mode, the high side and low side MOSFETs are turned-off, and the entire
internal control circuitry is switched-off. If disabled, the outputs of the DC-DC converters are pulled low by
internal 250-Ω resistors, actively discharging the output capacitor. For proper operation the enable pins must be
terminated and must not be left floating.
Optionally, there is internal sequencing for the DC-DC converters and both LDOs available. Bits DCDC_SQ[0..2]
in register CON_CTRL1 define the start-up and shut-down sequence for the DC-DC converters. Depending on
the sequencing option, the signal at EN_DCDC1, EN_DCDC2 and EN_DCDC3 are ignored. For automatic
internal sequencing, the enable signals which are not used should be connected to GND.
Note: If there is a load on the SYS pin the DC-DC's wont go through a soft start.
I have also seen a problem if PB_OUT and POWER_ON are not pulled up with SYS. I see that you are using the +3.3V_FPGA. As a test you might try to pull them up to SYS.
Please take a look at these ideas and let me know what you find. I will continue to look over your information for other suggestions.
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