ir3084a International Rectifier Corp., ir3084a Datasheet - Page 22

• Manufacturer Part Number: ir3084a
• Description: Xphase Tm Vr 10/11 Control Ic
• Manufacturer: International Rectifier Corp.

System Reference Voltage (VBIAS)
The IR3084A supplies a 6.9V/6mA precision reference voltage from the VBIAS pin. The oscillator ramp trip points
are based on the VBIAS voltage so it should be used to program the Phase ICs phase delay to minimize phase
errors.
Phase IC Gate Driver Bias Regulator / VRHOT Comparator
An internal amplifier can be configured as a gate driver bias regulator to provide programmable gate driver
voltage for phase ICs (Figure 12a), or a thermal monitor to provide VRHOT/VRFAN signal as required in VR11
(Figure 12b).
The internal current source IREGSET whose value is programmed by the switching frequency going through the
external RSET resistor sets the gate driver voltage or the VRHOT/VRFAN threshold voltage. An NTC thermistor
is used to monitor the temperature on the VRM/VRD.
Page 22 of 45
R2
100K
CVGDRV
10nF
Figure 12a – IR3084A Bias Regulator configured for Gate Driver Bias Regulator
R1
10K
R3
3K
RH2
36K
Figure 12b – IR3084A Bias Regulator configured for VRHOT# Function
C1
1nF
RVGDRV
97.6K
REGSET
REGFB
IR3084 CONTROL IC
VBIAS
REGSET
IR3084 CONTROL IC
VCC
RH1
1.1MEG
IREGSET
+
-
VCC
IREGSET
REGDRV
+
-
REGDRV
REGFB
R4
2K
R5
1K
C2
10nF
+12V
+
RPU
1ohm / 1206
Q1
CJD200
C3
10uF
+3.3V
RPU1
2K
VGDRIVE
Q5
2N7002
VRHOT#
IR3084A
10/30/2006