ir3092 International Rectifier Corp., ir3092 Datasheet - Page 11

• Manufacturer Part Number: ir3092
• Description: 2 Phase Opteron, Athlon, Or Vr10.x Control Ic
• Manufacturer: International Rectifier Corp.

The RSFF is reset dominant allowing both phases to go to zero duty cycle within a few tens of nanoseconds in response
to a load step decrease. Phases can overlap and go to 100% duty cycle in response to a load step increase with turn-on
gated by the clock pulses. An Error Amplifier output voltage greater than the common mode input range of the PWM
comparator results in 100% duty cycle regardless of the voltage of the PWM ramp. This arrangement guarantees the
Error Amplifier is always in control and can demand 0 to 100% duty cycle as required. It also favors response to a load
step decrease which is appropriate given the low output to input voltage ratio of most systems. The inductor current will
increase much more rapidly than decrease in response to load transients.
This control method is designed to provide “single cycle transient response” where the inductor current changes in
response to load transients within a single switching cycle maximizing the effectiveness of the power train and minimizing
the output capacitor requirements.
Page 11 of 37
CDAC
RDAC
RFB
CCOMP
RCOMP
CSC2
RSC2
RDRP
ROSC
VDAC
VOSNS-
EAOUT
SCOMP
ROSC
FB
VDRP
VDAC
IROSC
80mV
U39
VDRP BUFFER
OSCBLOCK
+
-
IROSC
ERROR AMPLIFIER
CLK1
CLK2
+
-
CLK2
Share Adjust Error Amp
0.55V
+
-
BB DISABLE
-
+
0% DUTY CY CLE
PWM COMPARATOR
Figure 2 – PWM Block Diagram
+
-
0 TO IROSC*3/4
PWM COMPARATOR
-
+
-
+
CLK2
10p
RESET DOMINANT
10p
S
R
RESET DOMINANT
RSFF
S
R
RSFF
QB
IROSC/2
QB
IROSC
VDAC
VDAC
0.7V
0.7V
X24.5
X24.5
+
+
-
-
GATEH1
GATEL1
GATEH2
GATEL2
CSINP2
CSINM
CSINP1
VIN
VIN
1
RCS2
1
CCS2
RCS1
2
06/25/04
CCS1
2
IR3092
COUT
VOUT SENSE+
VOUT+
VOUT-
VOUT SENSE-