User Manual
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V 1.0
2021-08-25
XDPP1100 technical reference manual
Digital power controller
Flux balance (FBAL)
•
fbal_dcm_thresh
, which sets the current threshold at which the flux balance function is disabled due to the
DCM operation; a setting of 63 disables this feature (not recommended)
•
fbal_dcm_dis_cnt
, which defines the number of consecutive current samples (at F
switch
rate) below
fbal_dcm_thresh
required to disable the flux balance function; a higher setting helps to reduce jitter near
the DCM boundary
•
fbal_dcm_ena_cnt
defines the number of consecutive current samples (at F
switch
rate) above
fbal_dcm_thresh
required to enable the flux balance function; a higher setting will help reduce jitter near
the DCM boundary
•
fbal_dcm_0out_duty_adj
defines what action is taken with the
fbal_duty_adj
output on DCM disable,
either freeze or reset to 0
12.5
Flux balance fault detection
If the flux balance circuit is unable to achieve balance between half-cycles, it can be configured to declare a
fault. Flux balance fault detection diagram is shown in
Figure 95
Flux balance fault detection block diagram
The following methods are provided to detect a flux balance fault:
•
Absolute volt-second error
•
Accumulated integrator error
In order to declare a flux balance fault, these error methods compare:
•
For absolute error, a low-pass filtered version of the PI filter input to a specified register value in
flux_bal_thresh
•
For accumulated error, a PI filter integral term accumulated error to a specified register value in
fbal_integ_thresh
.
A setting of 0 on
flux_bal_thresh
disables the absolute error fault method and, correspondingly, a setting of 0
on
fbal_integ_thresh
disables the accumulated error method.
0
1
vbal_mode_sel
kp_fbal
ki_fbal
vdt_plus_tdv
vdiff
integ_accum
abs()
abs()
0
1
fbal_delta_abs_en
error
abs()
fbal_lpf_kpshift
0
1
+
-
+
-
flux_bal_thresh
fbal_integ_thresh
fbal_fault
PI Filter
LPF
