ISL6364 Datasheet, PDF (40/44 Pages) Intersil Corporation – Dual 4-Phase + 1-Phase PWM Controller for VR12/IMVP7 Applications

ISL6364
TABLE 14. PIN DESIGN AND/OR LAYOUT CONSIDERATION
(Continued)
NOISE
PIN NAME SENSITIVITY
DESCRIPTION
VR_RDY
No
Open drain and high dv/dt pin. Avoid its
pull-up higher than VCC. Tie it to ground
when not used.
IMONS
Yes
Referring to GND, not RGNDS. Place R and
C in general proximity to the controller. The
time constant of RC should be sufficient,
typically 1ms, as an average function for
the digital IOUT of VR1.
VR_HOT#
No
Open drain and high dv/dt pin during
transitions. Avoid its pull-up rail higher
than VCC. 30 mils spacing from other
traces.
HFCOMPS/D
Yes
Connect an R in similar value (equal or
VCS
slight higher) of the feedback resistor. If
programmed to be used as DVCS, Connect
an RC to FBS from this pin. Placing the
compensation network in close proximity
to the controller.
VR_RDYS
No
Open drain and high dv/dt pin. Avoid its
pull-up higher than VCC. Tie it to GND when
not used.
COMPS
Yes
Placing the compensation network in close
proximity to the controller. Typically use a
68pF or higher across FBS to COMPS
depending upon the noise coupling of the
layout.
FBS
Yes
Pairing up with the negative rail of remote
sensing line that connected to RGNDS, and
routing them to the load sensing points.
Reserve an RC from FBS to GND to
compensate the output lagging from DAC
during DVID transitions.
VSENS
No
Used for Overvoltage protection sensing
only, and it has 1µs internal filter.
Decoupling is NOT needed. Add a series
impedance to be compatible with
ISL6364A.
RGNDS
Pairing up with the positive rail remote
sensing line that connected to FB resistor,
and routing them to the load sensing
points.
FSS_DDRS
Yes
Placing the R in close proximity to the
controller. Avoid using decoupling
capacitor on this pin. Must tie GND or VCC
via 1MΩ depending upon the desired
ADDRESS offset when VR1 is not in use.
Don’t use decoupling capacitor on this pin.
To minimize the effect of cross coupling
between regulators, select operating
frequencies of VR0 and VR1 at least 50kHz
apart.
TABLE 14. PIN DESIGN AND/OR LAYOUT CONSIDERATION
(Continued)
NOISE
PIN NAME SENSITIVITY
DESCRIPTION
TMS
Placing NTC in close proximity to the
output inductor of VR1 and to the output
rail, not close to MOSFET side (see Figure
23); the return trace should be 25 mils
away from other traces. Place 1k pull-up
and decoupling capacitor (typically 0.1µF)
in close proximity to the controller. The
pull-up resistor should be exactly tied to
the same point as VCC pin, not through an
RC filter. If not used, connect this pin to TM
or 1MΩ/2MΩ resistor divider, but DON’T
tie it to VCC or GND. Place the NTC in
proximity to the output rail, not close to
MOSFET side.
ISENS+
Yes Connect to the output rail side of the
output inductor or current sensing resistor
pin with Isen resistor and decoupling
capacitor (27ns) placed in close proximity
to the controller.
ISENS-
Yes Connect to the phase node side of the
output inductor or resistor pin with L/DCR
or ESL/R_SEN matching network in close
proximity to the ISENS±- pins of the
controller. Differential pair with ISENS+
routing back to the controller.
PWMS
No
Avoid the routing across or under other
phase’s power trains and DCR sensing
network. Don’t make them across or under
external components of the controller. At
least 30mils away from any other traces.
ADDR_XX;
NPSI_XX;
BT_XX;
BTS_XX
No
Register setting is locked prior to soft start.
Since the external resistor-divider ratio
compares with the internal resistor ratio of
the VCC, their rail should be exactly tied to
the same point as VCC pin, not through an
RC filter. DON’T use decoupling capacitors
on these pins.
TM
Placing NTC in close proximity to the
output inductor of VR0’s Channel 1 and to
the output rail, not close to MOSFET side
(see Figure 23); the return trace should be
25 mils away from other traces. Place 1k
pull-up and decoupling capacitor (typically
0.1µF) in close proximity to the controller.
The pull-up resistor should be exactly tied
to the same point as VCC pin, not through
an RC filter. If not used, connect this pin to
TMS or 1M Ω/2M Ω resistor divider, but
DON’T tie it to VCC or GND.
SICI
No
Program SI (standard-inductor, tied to
GND) and CI (coupled inductor, tied to
VCC). It is reserved for IAUTO in ISL6364A
and will be noise sensitive; SI and CI are
still programmable with this pin.
RSET
Yes
Placing the R in close proximity to the
controller. DON’T use decoupling capacitor
on this pin.
40
FN6861.0
December 22, 2010