Rainbow Electronics MAX17008 - Manual (Page 25)

Additional load current can slow down the output volt-
age change during a positive REFIN1 voltage change,
and can speed up the output voltage change during a
negative REFIN1 voltage change.
Automatic Fault Blanking (SMPS1)
When the MAX17007A/MAX17008 detect that the inter-
nal target and REFIN1 are more than ±50mV (typ)
apart, the controller automatically blanks PGOOD1,
blanks the UVP protection, and sets the OVP threshold
to max REF + 300mV. The blanking remains until 1) the
internal target and REFIN1 are within ±50mV of each
other, and 2) an edge is detected on the error amplifier
signifying that the output is in regulation. This prevents
the system or internal fault protection from shutting down
the controller during transitions. Figure 11 shows the
dynamic REFIN1 transition (SKIP = GND) and Figure 12
shows the dynamic REFIN1 transition (SKIP = REF).
MAX17007A/MAX17008
Dual and Combinable QPWM Graphics
Core Controllers for Notebook Computers
______________________________________________________________________________________ 25
INTERNAL
PWM CONTROL
REFIN1
BLANK HIGH-Z
SKIP
LX1
SET TO REF + 300mV
V
OUT1
INTERNAL TARGET1
ACTUAL V OUT1
BLANK HIGH-Z
DYNAMIC REFIN1 WINDOW
TARGET1 + 300mV
-50mV
PGOOD1 LOWER
THRESHOLD + UVP1
PGOOD1 UPPER
THRESHOLD + OVP1
NO PULSES: V OUT1 > V TARGET1
Figure 11. Dynamic REFIN1 Transition (SKIP = GND)
INTERNAL
PWM CONTROL
V OUT1
REFIN1
BLANK HIGH-Z
SKIP
LX1
REF + 300mV
INTERNAL TARGET1 = ACTUAL V OUT1
BLANK HIGH-Z
SKIP
200 μs 200 μs
+50mV
-50mV
PGOOD1 LOWER
THRESHOLD + UVP1
PGOOD1 UPPER
THRESHOLD + OVP1
PWM PWM
TARGET1 + 300mV TARGET1 + 300mV
DYNAMIC REFIN1 WINDOW
Figure 12. Dynamic REFIN1 Transition (SKIP = REF)