HIP6020ACB Intersil Corporation, HIP6020ACB Datasheet - Page 7

• Manufacturer Part Number: HIP6020ACB
• Description: Advanced Dual PWM and Dual Linear Power Controller
• Manufacturer: Intersil Corporation

to 1.5V, while a high input turns Q3 on continuously,
providing a DC current path from the input (+3.3V) to the
output (V
DRIVE3 (Pin 18)
Connect this pin to the gate of an external MOSFET. This pin
provides the drive for the 1.5V regulator’s pass transistor.
FB3 (Pin 19)
Connect this pin to the output of the 1.5V linear regulator.
This pin is monitored for undervoltage events.
DRIVE4 (Pin 15)
Connect this pin to the gate of an external MOSFET. This pin
provides the drive for the 1.8V regulator’s pass transistor.
FB4 (Pin 14)
Connect this pin to the output of the linear 1.8V regulator.
This pin is monitored for undervoltage events.
Description
Operation
The HIP6020A monitors and precisely controls 4 output voltage
levels (Refer to Figures 1, 2, and 3). It is designed for
microprocessor computer applications with 3.3V, 5V, and 12V
bias input from an ATX power supply. The IC has 2 PWM and
two linear controllers. The first PWM controller (PWM1) is
designed to regulate the microprocessor core voltage (V
PWM1 controller drives 2 MOSFETs (Q1 and Q2) in a
synchronous-rectified buck converter and regulates the core
voltage to a level programmed by the 5-bit digital-to-analog
converter (DAC). The second PWM controller (PWM2) is
designed to regulate the advanced graphics port (AGP) bus
voltage (V
standard buck converter and regulates the output voltage to a
level of 1.5V or fully on to output 3.3V. Selection of either output
voltage is achieved by applying the proper logic level at the
SELECT pin. The two linear controllers supply the 1.5V GTL
bus power (V
Initialization
The HIP6020A automatically initializes upon receipt of input
power. Special sequencing of the input supplies is not
necessary. The Power-On Reset (POR) function continually
monitors the input supply voltages. The POR monitors the
bias voltage (+12V
(+5V
(+3.3V
equal to +5V
protection). The POR function initiates soft-start operation
after all supply voltages exceed their POR thresholds.
Soft-Start
The POR function initiates the soft-start sequence. Initially, the
voltage on the SS pin rapidly increases to approximately 1V
(this minimizes the soft-start interval). Then an internal 28 A
current source charges an external capacitor (C
IN
IN
) on the OCSET1 pin, and the 3.3V input voltage
) at the VAUX pin. The normal level on OCSET1 is
OUT2
OUT2
OUT3
IN
) of the AGP controller.
). PWM2 controller drives a MOSFET (Q3) in a
less a fixed voltage drop (see over-current
) and the 1.8V memory power (V
IN
) at the VCC pin, the 5V input voltage
4-7
SS
) on the SS
OUT4
OUT1
).
HIP6020A
).
pin to 4.5V. The PWM error amplifiers reference inputs
(+ terminal) and outputs (COMP1 pin) are clamped to a level
proportional to the SS pin voltage. As the SS pin voltage slews
from 1V to 4V, the output clamp allows generation of PHASE
pulses of increasing width that charge the output capacitor(s).
After the output voltage increases to approximately 70% of the
set value, the reference input clamp slows the output voltage
rate-of-rise and provides a smooth transition to the final set
voltage. Additionally both linear regulators’ reference inputs are
clamped to a voltage proportional to the SS pin voltage. This
method provides a rapid and controlled output voltage rise.
Figure 6 shows the soft-start sequence for the typical
application. At T0 the SS voltage rapidly increases to
approximately 1V. At T1, the SS pin and error amplifier
output voltage reach the valley of the oscillator’s triangle
wave. The oscillator’s triangular wave form is compared to
the clamped error amplifier output voltage. As the SS pin
voltage increases, the pulse-width on the PHASE pin
increases. The interval of increasing pulse-width continues
until each PWM output reaches sufficient voltage to transfer
control to the error amplifier input reference clamp. If we
consider the core output (V
occurs at T2. During the interval between T2 and T3, the
error amplifier reference ramps to the final value and the
converter regulates the output a voltage proportional to the
SS pin voltage. At T3 the input clamp voltage exceeds the
reference voltage and the output voltage is in regulation.
0V
0V
0V
VOLTAGES
(0.5V/DIV)
T0
OUTPUT
T1
SOFT-START
FIGURE 3. SOFT-START INTERVAL
PGOOD
(1V/DIV)
T2
OUT1
TIME
) in Figure 6, this time
T3
V
OUT1
V
V
V
OUT3
OUT2
OUT4
(DAC = 2.5V)
( = 1.5V)
( = 3.3V)
( = 1.8V)
T4