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PDF ISL6432CB Data sheet ( Hoja de datos )
| Número de pieza | ISL6432CB | |
| Descripción | PWM and Triple Linear Power Controller for Home Gateway Applications | |
| Fabricantes | Intersil Corporation | |
| Logotipo |  |
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TM
Data Sheet
ISL6432
June 2001
File Number 9019
PWM and Triple Linear Power Controller
for Home Gateway Applications
The ISL6432 provides the power control and protection for
four output voltages for use with high-performance
microprocessor and embedded controller based
communications chip sets. The IC integrates a voltage-mode
PWM controller and three linear controllers, as well as
monitoring and protection functions into a 16-lead SOIC
package. The PWM controller is intended to regulate the
microprocessor memory core voltage with a synchronous-
rectified buck converter. The linear controllers can be
configured to generate DSP power, as well as upstream and
downstream voltages. Both the switching regulator and
linear voltage references provide ±2% of static regulation
over line, load, and temperature ranges. All outputs are user-
adjustable by means of an external resistor divider. All linear
controllers employ bipolar NPNs for the pass transistors.
The ISL6432 monitors all the output voltages. The PWM
controller’s adjustable overcurrent function monitors the
output current by using the voltage drop across the upper
MOSFET’s rDS(ON). The linear regulator outputs are
monitored via the FB pins for undervoltage events.
Ordering Information
PART NUMBER TEMP. RANGE (oC) PACKAGE
PKG.
NO.
ISL6432CB
0 to 70
16 Ld SOIC M16.15
ISL6432EVAL1 Evaluation Board
Applications
• Low-Power Distributed DC-DC Conversion
• Cable Modem and DSL Modem Power Regulation
• High Performance Memory Applications
Features
• Provides 4 Regulated Voltages
- Memory Core, Embedded Controller/DSP, Tuner
• Drives Bipolar Linear Pass Transistors
• Externally Resistor-Adjustable Outputs
• Simple Single-Loop Control Design
- Voltage-Mode PWM Control
• Fast PWM Converter Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Ratio
• Excellent Output Voltage Regulation
- All Outputs: ±2% Over Temperature
• Overcurrent Fault Monitors
- Switching Regulator Does Not Require Extra Current
Sensing Element, Uses MOSFET’s rDS(ON)
• Small Converter Size
- 300kHz Constant Frequency Operation
- Small External Component Count
• ACPI Compatible
• Voltage Sequencing
Pinout
ISL6432 (SOIC)
TOP VIEW
DRIVE2 1
FB2 2
FB 3
COMP 4
GND 5
PHASE 6
BOOT 7
UGATE 8
16 FB3
15 DRIVE3
14 FB4
13 DRIVE4
12 OCSET
11 VCC
10 LGATE
9 PGND
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil and Design is a trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2001, All Rights Reserved
1 page  
ISL6432
Functional Pin Descriptions
VCC (Pin 11)
Provide a well decoupled 5V bias supply for the IC to this
pin. This pin also provides the gate bias charge for the lower
MOSFET controlled by the PWM section of the IC, as well as
the base current drive for the linear regulators’ external
bipolar transistors. The voltage at this pin is monitored for
Power-On Reset (POR) purposes.
GND (Pin 5)
Signal ground for the IC. All voltage levels are measured with
respect to this pin.
PGND (Pin 9)
This is the power ground connection. Tie the synchronous
PWM converter’s lower MOSFET source to this pin.
BOOT (Pin 7)
Connect a suitable capacitor (0.47µF recommended) from
this pin to PHASE. This bootstrap capacitor supplies UGATE
driver the energy necessary to turn and hold the upper
MOSFET on.
OCSET (Pin 12)
Connect a resistor from this pin to the drain of the upper
PWM MOSFET. This resistor, an internal 40µA current
source (typical), and the upper MOSFET’s on-resistance set
the converter overcurrent trip point. An overcurrent trip
cycles the soft-start function.
The voltage at this pin is monitored for power-on reset (POR)
purposes and pulling this pin below 1.25V with an open
drain/collector device will shutdown the switching controller.
PHASE (Pin 6)
Connect the PHASE pin to the PWM converter’s upper
MOSFET source. This pin is used to monitor the voltage
drop across the upper MOSFET for overcurrent protection.
UGATE (Pin 8)
Connect UGATE pin to the PWM converter’s upper MOSFET
gate. This pin provides the gate drive for the upper MOSFET.
LGATE (Pin 10)
Connect LGATE to the PWM converter’s lower MOSFET
gate. This pin provides the gate drive for the lower MOSFET.
COMP and FB (Pins 4, 3)
COMP and FB are the available external pins of the PWM
converter error amplifier. The FB pin is the inverting input of the
error amplifier. Similarly, the COMP pin is the error amplifier
output. These pins are used to compensate the voltage-mode
control feedback loop of the synchronous PWM converter.
DRIVE2, 3, 4 (Pins 1, 15, 13)
Connect these pins to the base terminals of external bipolar
NPN transistors. These pins provide the base current drive
for the regulator pass transistors.
FB2, 3, 4 (Pins 2, 16, 14)
Connect the output of the corresponding linear regulators to
these pins through properly sized resistor dividers. The
voltage at these pins is regulated to 0.8V. These pins are
also monitored for undervoltage events.
Quickly pulling and holding any of these pins above 1.25V
(using diode-coupled logic devices) shuts off the respective
regulators. Releasing these pins from the pull-up voltage
initiates a soft-start sequence on the respective regulator.
Description
Operation
The ISL6432 monitors and precisely controls 4 output
voltage levels (Refer to Block and Simplified Power System
Diagrams, and Typical Application Schematic). The IC has a
synchronous PWM controller and three linear controllers.
The PWM controller drives 2 MOSFETs (Q1 and Q2) in a
synchronous-rectified buck converter configuration and
regulates the output voltage to a level programmed by a
resistor divider. The linear controllers are designed to
regulate three more of the communication chip set
voltages. All linear controllers are designed to employ
external NPN bipolar pass transistors.
Initialization
The ISL6432 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 bias supply voltage. The POR monitors
the bias voltage at the VCC pin. The POR function initiates
soft-start operation after the bias supply voltage exceeds its
POR threshold.
Soft-Start
The POR function initiates the soft-start sequence. The
PWM error amplifier reference input is clamped to a level
proportional to the soft-start voltage. As the soft-start voltage
slews up, the PWM comparator generates PHASE pulses of
increasing width that charge the output capacitor(s).
Similarly, all linear regulators’ reference inputs are clamped
to a voltage proportional to the soft-start voltage. The ramp-
up of the internal soft-start function provides a controlled
output voltage rise.
Overcurrent Protection
All outputs are protected against excessive overcurrents.
The PWM controller uses the upper MOSFET’s
on-resistance, rDS(ON) to monitor the current for protection
against shorted output. All linear controllers monitor their
respective FB pins for undervoltage events to protect against
excessive currents.
A sustained overload (undervoltage on linears or overcurrent
on the PWM) on any output results in an independent
shutdown of the respective output, followed by subsequent
individual re-start attempts performed at an interval equivalent
to 3 soft-start intervals. Figure 1 describes the protection
feature. At time T0, an overcurrent event sensed across the
switching regulator’s upper MOSFET (rDS(ON) sensing)
triggers a shutdown of the VOUT1 output. As a result, its
internal soft-start initiates a number of soft-start cycles. After a
5
5 Page 
ISL6432
ISL6432 DC-DC Converter Application Circuit
Figure 8 shows an application circuit. For detailed information
on the circuit, including a Bill-of-Materials and circuit board
description, please refer to the Power Management Home
Gateway section on Intersil’s web page (www.intersil.com)
+5V
GND
+3.3VIN
VOUT2
Q3
FZT649
(2.5V)
C8 +
330µF
+3.3V
VOUT3
(1.8V)
Q4
2SD1802
+ C10
1000µF
VOUT4
(1.5V)
Q5
2SD1802
+ C2
1000µF
C1 +
R2
12.7K
DRIVE2
1
FB2
2
R3
5.90K
R4
9.09K
DRIVE3
15
FB3 16
R5
7.15K
R9
7.50K
DRIVE4
13
FB4
14
R10
8.45K
VCC
11
C4
1µF C5
1000pF
12
OCSET
7
BOOT
R1
12K
C6
1µF
D1
MA732
8 UGATE
6
PHASE
U1
ISL6432
10 LGATE
PGND
9
C7
0.47µF
L2
Q1,2
HUF76129D3S
2.5µH
C9 +
FB
3
COMP
4
C14
10pF
5
GND
C3 R7
22nF 45.3K
R6
1.50K
R8
698
VOUT1
(2.5V)
FIGURE 8. POWER SUPPLY APPLICATION CIRCUIT FOR A MICROPROCESSOR COMPUTER SYSTEM
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ISL6432CB.PDF ] | |
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