User Manual
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V 1.0
2021-08-25
XDPP1100 technical reference manual
Digital power controller
Voltage control
𝑣𝑐_𝑣𝑎𝑣𝑝_𝑟𝑙𝑙_𝑛𝑒𝑔 =
𝑀𝐹𝑅_𝑅𝐷𝑅𝑂𝑂𝑃_𝑅𝐿𝐿_𝑁𝐸𝐺∗𝑉𝑂𝑈𝑇_𝑆𝐶𝐴𝐿𝐸_𝐿𝑂𝑂𝑃
2
(𝑦+9)
(5.12)
𝑦 = −1 ∗ 𝐿𝐼𝑁𝐸𝐴𝑅11 𝑒𝑥𝑝𝑜𝑛𝑒𝑛𝑡 𝑜𝑓 𝑀𝐹𝑅_𝑅𝐷𝑅𝑂𝑂𝑃_𝑅𝐿𝐿_𝑁𝐸𝐺
(5.13)
It should be noted that the
vc_vavp_rll_xxx
registers are relative to VSEN while the PMBus droop commands
are relative to the output voltage. The block diagram of the droop voltage computation is shown in
Figure 43
Multi-segment droop block diagram
The current thresholds between the segments are defined through the following registers:
•
vc_vavp_ithr_seg2
for SEG1/SEG2
•
vc_vavp_ithr_seg3
for SEG2/SEG3
They are programmed via PMBus commands MFR_RDROOP_ITHR_SEG2 and MFR_RDROOP_ITHR_SEG3,
respectively. The output current used for the droop computation,
tlm_iout_fs
, comes from the telemetry
module. It is the switching-cycle averaged, unfiltered representation of I
OUT
. The FW can add an offset to the
measured output current via register
vc_vavp_itot_delta
. In addition, the FW can completely override the
measured I
OUT
for use in the droop computation through registers
vc_vavp_itot_uc
and
vc_vavp_itot_uc_sel
.
In order to determine in which current segment the XDPP1100 is operating, the current itot_mux is compared
to the segment current thresholds. The computed droop voltages in each of the four segments are described in
. The negative and SEG1 droop voltage (output on vdroop_hibw) is computed independently from the
SEG2/SEG3 droop voltage (output on vdroop_lobw). Segments 2 and 3 typically have higher droop resistance
requiring lower BW filtering to prevent output voltage oscillation.
gt_seg2
S12.3
vdroop_hibw[14:0]
vc_vavp_itot_delta[12:0]
S9.4
tlm_iout_fs[12:0]
S9.4
vc_vavp_itot_uc[12:0]
S9.4
vc_vavp_itot_uc_sel
vc_vavp_rll_neg[10:0]
LSB=16m/2048
vc_vavp_rll[10:0]
LSB=16m/2048
vc_vavp_rll_seg2[9:0]
LSB=0.5m
vc_vavp_rll_seg3[9:0]
LSB=0.5m
vc_vavp_ithr_seg2[9:0]
U8.1
vc_vavp_ithr_seg3[9:0]
U8.1
U11.3
vdroop_lobw[13:0]
S
+
+
0
1
A
B
C
S10.4
itot_mux[13:0]
A < 0
A > B
A > C
neg
gt_seg3
0
1
0
1
X
Clamp
0
1
0
1
0
1
0
0
X
X
S
+
+
Clamp
S
-
+
vdroop_seg1
vdroop_seg2
vdroop_seg3
S
-
+
