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Phlip Cornelissen
Phlip Cornelissen
Associate II
January 23, 2017
Solved

L6480 bootstrap charge pump stop after write of configuration register

  • January 23, 2017
  • 2 replies
  • 1029 views
Posted on January 23, 2017 at 11:35

The L6480 controller charge pump frequency stops after a write to the configuration register. A pulse on the reset pin seems to do nothing at all. Is there a proper sequence to restart the charge pump frequency? How can I fix this?

Controller setup:

16Mhz internal clock with no output, OSCOUT, OSCIN disabled

PWM frequency devision factor = 2

PWM frequency multiplication factor = 1

Config register value: 0x2F80

This topic has been closed for replies.
Best answer by Enrico Poli
Posted on February 01, 2017 at 14:16

Ok... This is quite strange.

Lets proceed step by step:

  1. Turn-on the device and check the charge pump: it should be operating.
  2. Clear the STATUS register using GetStatus (UVLO failure is always asserted at power-up) and then read the STATUS register again... UVLO should be no more present.
  3. Change the CONFIG register

    only

    . Is the charge pump still switching?
  4. Clear the STATUS register (GetStatus). Probably a UVLO failure is reported cause the internal regulator takes some time to rise the VCC up to 12 V (above new VCCUVLO  threshold). R

    eading the STATUS register again the UVLO should be no more present.

  5. Reset the device and read the CONFIG register: Is the configuration back to the default (2C88)? Is the charge pump switching?

2 replies

Enrico Poli
Enrico Poli
ST Employee
January 24, 2017
Posted on January 24, 2017 at 17:13

The charge pump is disabled in the following conditions:

  1. Device under reset
  2. Device supply below UVLO
  3. Wrong clock configuration (i.e. setting an external clock source with no actual clock available)

Cases 1 and 2 can be easily checked measuring the supplies and the STBY/RESET input values.

Case 3 should be recovered resetting the device (or through a power cycle), so check if your reset pulse is long enough to actually reset the internal registers.

Phlip Cornelissen
Phlip CornelissenAuthor
Associate II
January 25, 2017
Posted on January 25, 2017 at 06:43

Cases 1 or 2 were not active. I then read the initial boot value to change one setting at a time to figure out which setting stops the charge pump, it was either PWM settings (multiplication or division factors), so a change in PWM frequency stops the charge pump. I tried a 30ms Reset pulse (datasheet recommends 500uS) but it did not sove the problem. Any recommendations?

Enrico Poli
Enrico PoliBest answer
ST Employee
February 1, 2017
Posted on February 01, 2017 at 14:16

Ok... This is quite strange.

Lets proceed step by step:

  1. Turn-on the device and check the charge pump: it should be operating.
  2. Clear the STATUS register using GetStatus (UVLO failure is always asserted at power-up) and then read the STATUS register again... UVLO should be no more present.
  3. Change the CONFIG register

    only

    . Is the charge pump still switching?
  4. Clear the STATUS register (GetStatus). Probably a UVLO failure is reported cause the internal regulator takes some time to rise the VCC up to 12 V (above new VCCUVLO  threshold). R

    eading the STATUS register again the UVLO should be no more present.

  5. Reset the device and read the CONFIG register: Is the configuration back to the default (2C88)? Is the charge pump switching?
Phlip Cornelissen
Phlip CornelissenAuthor
Associate II
February 2, 2017
Posted on February 02, 2017 at 13:32

I did run through the whole sequence and found the problem, a double swop of the MSB and LSB values for the configuration register, instead of writing 2F80 the value written was 802F hex, problem now solved, Thanks!

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