isl8120 Intersil Corporation, isl8120 Datasheet - Page 31

• Manufacturer Part Number: isl8120
• Description: Dual/n-phase Buck Pwm Controller With Integrated Drivers
• Manufacturer: Intersil Corporation

on the loading, Channel 1 might drop faster than Channel 2.
To solve this race condition, Channel 2 can either power up
from Channel 1 or bridge the Channel 1 with a high current
Schottky diode. If the system requires to shutdown both
channels when either has a fault, tying EN/FF1 and EN/FF2
will do the job. In DDR mode, Channel 1 delays 60° over
Channel 2.
In Dual mode, depending upon the resistor divider level of
REFIN from VCC, the ISL8120 operates as a dual-PWM
controller for two independent regulators with a phase shift
as shown in Table 2. The phase shift is latched as VCC
raises above POR and cannot be changed on the fly.
MODE
DDR
Dual
Dual
Dual
REFIN RANGE
29% to 45% of
45% to 62% of
<29% of VCC
62% to VCC
DECODING
VOUT (LOCAL)
GND (LOCAL)
VCC
VCC
700mV
VCC
PHASE for CHANNEL
TABLE 2.
2 WRT CHANNEL 1
VSENSE- (REMOTE)
10Ω
10Ω
31
180°
-60°
FIGURE 23. SIMPLIFIED REMOTE SENSING IMPLEMENTATION
90°
0°
VSEN-
C
SEN
R
OS
VSEN+
R
REQUIRED
GAIN=1
FB
VSENSE+ (REMOTE)
37% VCC
53% VCC
REFIN
VCC
0.6V
V
VMON
REF
ISL8120
Z
FB
OV/UV
COMP
k*R
R
VDDQ
FB
FIGURE 24. SIMPLIFIED DDR IMPLEMENTAION
Z
ERROR AMP
COMP
Internal SS
PHASE-SHIFTED
CLKOUT/REFIN
k
=
CLOCK
VDDQ
----------------- - 1
0.6V
COMP
–
PGOOD
0.6V
FB2
PGOOD
VCC
700mV
VSEN2-
MACHINE
March 28, 2008
E/A2
ISL8120
STATE
FN6641.0