Notebook CPU Step-Down Controller for Intel
-
Mobile Voltage Positioning (IMVP II)
3.3V
R
R
R
R
R = 100kΩ
R
R
R
R
R
VID4
VID3
VID2
VID1
VID0
CPU
MAX1718
ZMODE
3.3V
3.3kΩ
1nF
MAX1609
ADD0
ADD1
ADDRESS
0
1
0
1
0
1
1
1
1
1
DATA
SMBUS
CLOCK
SMBSUS
GMUXSEL
Figure 14. Using the ZMODE Multiplexer
voltage. If the output is more than 2V, OVP is triggered
and the circuit shuts down. The DL low-side gate-driver
output is then latched high until SKP/SDN is toggled or
Output Undervoltage Shutdown
The output UVP function is similar to foldback current
limiting, but employs a timer rather than a variable cur-
rent limit. If the MAX1718 output voltage is under 70% of
the nominal value, the PWM is latched off and won’t
V
power is cycled below 1V. This action turns on the
CC
synchronous-rectifier MOSFET with 100% duty and, in
turn, rapidly discharges the output filter capacitor and
forces the output to ground. If the condition that caused
the overvoltage (such as a shorted high-side MOSFET)
persists, the battery fuse will blow. DL is also kept high
restart until V
power is cycled or SKP/SDN is tog-
CC
gled. To allow startup, UVP is ignored during the under-
voltage fault-blanking time (the first 256 cycles of the
slew rate after startup).
continuously when V
UVLO is active, as well as in
CC
UVP can be defeated through the NO FAULT test mode
(see the NO FAULT Test Mode section).
shutdown mode (Table 6).
Overvoltage protection can be defeated with a logic
high on OVP or through the NO FAULT test mode (see
the NO FAULT Test Mode section).
______________________________________________________________________________________ 23
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
