ISL6440A Datasheet, PDF (1/16 Pages) Intersil Corporation – Advanced PWM and Triple Linear Power Controller for Gateway Applications

TM
Data Sheet
ISL6440A
October 2001
File Number 9041
Advanced PWM and Triple Linear Power
Controller for Gateway Applications
The ISL6440A provides the power control and protection for
four output voltages required by microprocessors used in
high-performance, graphics-intensive gateway applications.
The IC integrates a voltage-mode PWM controller and three
linear controllers, as well as the monitoring and protection
functions into a 28 lead SOIC package.
The synchronous rectified buck converter includes an Intel®-
compatible, TTL five-input, digital-to-analog converter (DAC)
that adjusts the core PWM output voltage from 1.3V_DC to
2.05V_DC in 0.05V steps and from 2.1V_DC to 3.5V_DC in 0.1V
increments. The precision reference and voltage-mode
control provide ±1% static regulation. A TTL-compatible
signal applied to the SELECT pin dictates which method of
control is used for the AGP bus power. A low state results in
linear control of the AGP bus to 1.5V, while a high state
transitions the output through a linearly controlled soft-start
to 3.3V, followed by full enhancement of the external
MOSFET to pass the input voltage. The other two linear
regulators provide fixed output voltages of 1.5V GTL bus
power and 1.8V power for the north/south bridge core and/or
cache memory. These levels are user-adjustable by means
of an external resistor divider and pulling the FIX pin low. All
linear controllers can employ either N-Channel MOSFETs or
bipolar NPNs for the pass transistor.
The ISL6440A monitors all the output voltages. A single
power good signal is issued when the core is within ±10% of
the DAC setting and all other outputs are above their under-
voltage levels. Additional built-in overvoltage protection for
the core output uses the lower MOSFET to prevent output
voltages above 115% of the DAC setting. The PWM
controller’s overcurrent function monitors the output current
by using the voltage drop across the upper MOSFET’s
r_DS(ON).
Ordering Information
PART NUMBER
ISL6440ACB
TEMP.
RANGE (^oC)
PACKAGE
0 to 70 28 Ld SOIC
PKG.
NO.
M28.3
Features
• Provides four regulated voltages
- Microprocessor core, AGP bus, memory, and GTL bus
power
• Drives N-Channel MOSFETs
• Linear regulator drives compatible with both MOSFET and
bipolar series pass transistors
• Fixed or externally resistor-adjustable linear outputs
• Simple single-loop control design
- Voltage-mode PWM control
• Fast PWM converter transient response
- High-bandwidth error amplifier
- Full 0–100% duty ratio
• Excellent output voltage regulation
- Core PWM output: ±1% over temperature
- Other outputs: ±3% over temperature
• TTL-compatible 5-bit DAC core output voltage selection
- Shutdown feature removed when all inputs high
- Wide range 1.3V_DC to 3.5V_DC
• Power-good output voltage monitor
• Overvoltage and overcurrent fault monitors
- Switching regulator does not require extra current
Sensing element, uses upper MOSFET’s r_DS(ON)
• Small converter size
- Constant frequency operation
- 200kHz free-running oscillator; programmable from
50kHz to over 1MHz
- Small external component count
Applications
• Power regulation for gateway processors
Pinout
ISL6440A (SOIC)
TOP VIEW
DRIVE2 1
FIX 2
VID4 3
VID3 4
VID2 5
VID1 6
VID0 7
PGOOD 8
SD 9
VSEN2 10
SELECT 11
SS 12
FAULT/RT 13
VSEN4 14
28 VCC
27 UGATE
26 PHASE
25 LGATE
24 PGND
23 OCSET
22 VSEN1
21 FB
20 COMP
19 VSEN3
18 DRIVE3
17 GND
16 VAUX
15 DRIVE4
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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