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TPS55288EVM-045: Evaluation Module Boost Mode Output

Part Number: TPS55288EVM-045
Other Parts Discussed in Thread: USB2ANY

Hi there, 

I wonder what needs to be taken into account when using the TPS55288EVM-045 evaluation board.

At the moment using TPS55288EVM-045, USB2ANY and TPS55288EVM GUI in following configuration:


Input Voltage: +3.6V standard Lithium Ion Battery 18650, how ever in this case a Bench PSU is used with 4A current capability.

Software/Register Setup:

Operating Mode: Boost

System Settings: Internal

Frequency Oscillation: Double

Hiccup: Enabled

Short Circuit protection: Disabled

Feedback: Internal

Discharge: Disable

Load: 150 OHm

Vout: 5V -> 20V

Hardware Setup:

Cable Lead Load: 100mm x 2 

Enable: set High

Feedback: Internal

VCC: Jumper Removed

Dithering: Jumper set to AGND

It seems that on Enable the systems starts at 5V so far so good, however it is impossible to set the output at 20V without the chip resetting or browning out, it seems that the output rises but then suddenly falls down in a matter of one second. It is possible to set the output to +20V by steadily increasing the output, i.e., set output enable then increase the reference voltage by a dozen millivolts at the time until it reaches 1200mV, while maintaining the feedback at 0.0564. 

The procedure shown above seems to able to set output to +20V, however it is impossible to set the output at the target +20V and then enable the chip without the browning out where the output is drops to 0V.