ISL68134_16 Datasheet, PDF (17/50 Pages) Intersil Corporation – Digital Dual Output, 7-Phase Configurable PWM

ISL68134
these paths affect PWM activity on a cycle-by-cycle basis. The
characteristics of each path are easily set in PowerNavigator™.
In addition to total output current, the ISL68134 provides an
individual phase peak current limit that will act on PWM in a
cycle-by-cycle manner. This means that if a phase current is
detected to exceed the OC threshold, the phase PWM signal will
be inverted to move current away from the threshold. In addition
to limiting positive or negative peak current on a cycle-by-cycle
basis, individual phase OC can be configured to limit current
indefinitely or to declare a fault after a programmable number of
consecutive OC cycles. This feature is useful for applications
where a fault shutdown of the system would not be acceptable,
however, some ability to limit phase currents is desired.
Figures 21 and 22 depict this operation. If configured for
indefinite current limit, the converter will act as a current source
and V_OUT will not remain at its regulation point. It should be
noted that in this case, V_OUT OV or UV protection action may
occur, which could shut the regulator down.
PH1 CURRENT
SYNTHESIZER
PHN CURRENT
SYNTHESIZER
ISUM


TOTAL OUTPUT CURRENT FAULT
FAST SUM OC
FILTER COMPARE
TIMER
ACT
FILTER LIMIT
TIMER
DELAY
TO
FAULT
BLOCK
SLOW SUM OC
FILTER COMPARE
TIMER
ACT
FILTER LIMIT
TIMER
DELAY
TO
FAULT
BLOCK
PHASE PEAK CURRENT LIMITING AND FAULT
IPHASEn
COMPARE
+PEAK
LIMIT
COMPARE
-PEAK
LIMIT
COUNT
fSW
CLK
Switching
Period
Count
May be set
for indefinite
limiting but
no fault
assertion
OCCOUNT
POSITIVE PEAK
LIMITING
COUNT
fSW
CLK
Switching
Period
Count
May be set
for indefinite
limiting but
no fault
assertion
UCCOUNT
NEGATIVE PEAK
LIMITING
ACT
TO
FAULT
BLOCK
PULSE BY
PULSE
LIMIT
ACT
TO
FAULT
BLOCK
PULSE BY
PULSE
LIMIT
FIGURE 18. OCP FUNCTIONAL DIAGRAM
Example OCP_Fast and OCP_Slow waveforms are shown in
Figures 19 and 20.
OCP_FAST_THRESHOLD
OCP_SLOW_THRESHOLD
PLACEHOLDER
FILTER TIME CONSTANT
OCP_SLOW COUNTER
PWM
PGOOD
FIGURE 20. OCP_Slow
POSITIVE_CURRENT_LIMITING_PER_PHASE
PWM
PGOOD
TWARN
FIGURE 21. POSITIVE PEAK PHASE CURRENT LIMITING
NEGATIVE_CURRENT_LIMITING_PER_PHASE
PWM
OCP_FAST_THRESHOLD
OCP_SLOW_THRESHOLD
PLACEHOLDER
FILTER TIME CONSTANT
OCP_FAST COUNTER
PWM
PGOOD
TWARN
FIGURE 22. NEGATIVE PEAK PHASE CURRENT LIMITING
PGOOD
FIGURE 19. OCP_Fast
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FN8817.0
September 28, 2016