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PDF ISL6430CR Data sheet ( Hoja de datos )
| Número de pieza | ISL6430CR | |
| Descripción | Single Sync Buck PWM Controller for Broadband Gateway Applications | |
| Fabricantes | Intersil Corporation | |
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®
Data Sheet
July 2003
ISL6430
FN9017.2
Single Sync Buck PWM Controller for
Broadband Gateway Applications
The ISL6430 provides complete control and protection for a
DC-DC converter optimized for high-performance broadband
gateway applications. It is designed to drive two N Channel
MOSFETs in a synchronous-rectified buck topology. The
ISL6430 integrates all of the control, output adjustment,
monitoring and protection functions into a single package.
The output voltage of the converter can be precisely
regulated to as low as 1.27V, with a maximum tolerance of
±1% over temperature and line voltage variations.
The ISL6430 provides simple, single feedback loop, voltage-
mode control with fast transient response. It includes a
200kHz free-running triangle-wave oscillator that is
adjustable from below 50kHz to over 1MHz. The error
amplifier features a 15MHz gain-bandwidth product and
6V/µs slew rate which enables high converter bandwidth for
fast transient performance. The resulting PWM duty ratio
ranges from 0% to 100%.
The ISL6430 protects against over-current conditions by
inhibiting PWM operation. The ISL6430 monitors the current
by using the rDS(ON) of the upper MOSFET which eliminates
the need for a current sensing resistor.
Ordering Information
TEMP.
PART NUMBER RANGE (oC)
PACKAGE
PKG. DWG. #
ISL6430CB
0 to 70 14 Ld SOIC
M14.15
ISL6430CR
0 to 70 16 Ld QFN
L16.5x5B
Add -T suffix to either option for tape and reel packaging.
Pinout
ISL6430 (SOIC)
TOP VIEW
RT 1
OCSET 2
SS 3
COMP 4
FB 5
EN 6
GND 7
14 VCC
13 PVCC
12 LGATE
11 PGND
10 BOOT
9 UGATE
8 PHASE
Features
• Drives Two N-Channel MOSFETs
• Operates From +5V or +12V Input
• Simple Single-Loop Control Design
- Voltage-Mode PWM Control
• Fast Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Ratio
• Excellent Output Voltage Regulation
- 1.27V Internal Reference
- ±1% Over Line Voltage and Temperature
• Over-Current Fault Monitor
- Does Not Require Extra Current Sensing Element
- Uses MOSFETs rDS(ON)
• Small Converter Size
- Constant Frequency Operation
- 200kHz Free-Running Oscillator Programmable from
50kHz to Over 1MHz
• 14-Lead SOIC and 16-Lead QFN
Applications
• Cable Modems, Set-Top Boxes and DSL Modems
• DSP and Core Communications Processor Supplies
• High-Power 5V Input DC-DC Regulators
• Low-Voltage Distributed Power Supplies
ISL6430 (QFN)
TOP VIEW
16 15 14 13
NC 1
COMP 2
FP 3
EN 4
12 PVCC
11 LGATE
10 PGND
9 BOOT
5678
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 registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2003. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL6430
Functional Description
Initialization
The ISL6430 automatically initializes upon receipt of power.
Special sequencing of the input supplies is not necessary.
The Power-On Reset (POR) function continually monitors
the input supply voltages and the enable (EN) pin. The POR
monitors the bias voltage at the VCC pin and the input
voltage (VIN) on the OCSET pin. The level on OCSET is
equal to VIN Less a fixed voltage drop (see over-current
protection). With the EN pin held to VCC, the POR function
initiates soft start operation after both input supply voltages
exceed their POR thresholds. For operation with a single
+12V power source, VIN and VCC are equivalent and the
+12V power source must exceed the rising VCC threshold
before POR initiates operation.
The Power-On Reset (POR) function inhibits operation with
the chip disabled (EN pin low). With both input supplies
above their POR thresholds, transitioning the EN pin high
initiates a soft start interval.
Soft Start
The POR function initiates the soft start sequence. An internal
10µA current source charges an external capacitor (CSS) on
the SS pin to 4V. Soft start clamps the error amplifier output
(COMP pin) and reference input (+ terminal of error amp) to
the SS pin voltage. Figure 3 shows the soft start interval with
CSS = 0.1µF.
SOFT-START
(1V/DIV)
OUTPUT
VOLTAGE
0V (1V/DIV)
0V
t1 t2
t3
TIME (5ms/DIV)
FIGURE 3. SOFT-START INTERVAL
Initially the clamp on the error amplifier (COMP pin) controls
the converter’s output voltage. At t1 in Figure 3, the SS
voltage reaches the valley of the oscillator’s triangle wave.
The oscillator’s triangular waveform is compared to the
ramping error amplifier voltage. This generates PHASE
pulses of increasing width that charge the output capacitor(s).
This interval of increasing pulse width continues to t2. With
sufficient output voltage, the clamp on the reference input
controls the output voltage. This is the interval between t2 and
t3 in Figure 3. At t3 the SS voltage exceeds the reference
voltage and the output voltage is in regulation. This method
provides a rapid and controlled output voltage rise.
4V
2V
0V
15A
10A
5A
0A
TIME (20ms/DIV)
FIGURE 4. OVER-CURRENT OPERATION
Over-Current Protection
The over-current function protects the converter from a
shorted output by using the upper MOSFETs on-resistance,
rDS(ON) to monitor the current. This method enhances the
converter’s efficiency and reduces cost by eliminating a
current sensing resistor.
The over-current function cycles the soft-start function in a
hiccup mode to provide fault protection. A resistor (ROCSET)
programs the over-current trip level. An internal 200µA
(typical) current sink develops a voltage across ROCSET that
is reference to VIN. When the voltage across the upper
MOSFET (also referenced to VIN) exceeds the voltage
across ROCSET, the over-current function initiates a soft-
start sequence. The soft-start function discharges CSS with
a 10µA current sink and inhibits PWM operation. The soft-
start function recharges CSS, and PWM operation resumes
with the error amplifier clamped to the SS voltage. Should an
overload occur while recharging CSS, the soft start function
inhibits PWM operation while fully charging CSS to 4V to
complete its cycle. Figure 4 shows this operation with an
overload condition. Note that the inductor current increases
to over 15A during the CSS charging interval and causes an
over-current trip. The converter dissipates very little power
with this method. The measured input power for the
conditions of Figure 4 is 2.5W.
The over-current function will trip at a peak inductor current
(IPEAK) determined by:
IPEAK
=
I--O-----C----S----E----T-----•----R----O-----C----S----E----T--
rDS(ON)
where IOCSET is the internal OCSET current source (200µA
- typical). The OC trip point varies mainly due to the
MOSFETs rDS(ON) variations. To avoid over-current tripping
5
5 Page 
ISL6430
Quad Flat No-Lead Plastic Package (QFN)
Micro Lead Frame Plastic Package (MLFP)
L16.5x5B
16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
(COMPLIANT TO JEDEC MO-220VHHB ISSUE C)
SYMBOL
A
A1
A2
A3
b
D
D1
MILLIMETERS
MIN NOMINAL MAX
0.80 0.90 1.00
- - 0.05
- - 1.00
0.20 REF
0.28 0.33 0.40
5.00 BSC
4.75 BSC
NOTES
-
-
9
9
5, 8
-
9
D2 2.95 3.10 3.25 7, 8
E
5.00 BSC
-
E1
4.75 BSC
9
E2 2.95 3.10 3.25 7, 8
e
0.80 BSC
-
k
0.25 -
--
L 0.35 0.60 0.75 8
L1 - - 0.15 10
N 16 2
Nd 4 3
Ne 4 3
P - - 0.60 9
θ - - 12 9
Rev. 1 10/02
NOTES:
1. Dimensioning and tolerancing conform to ASME Y14.5-1994.
2. N is the number of terminals.
3. Nd and Ne refer to the number of terminals on each D and E.
4. All dimensions are in millimeters. Angles are in degrees.
5. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
6. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.
7. Dimensions D2 and E2 are for the exposed pads which provide
improved electrical and thermal performance.
8. Nominal dimensions are provided to assist with PCB Land Pattern
Design efforts, see Intersil Technical Brief TB389.
9. Features and dimensions A2, A3, D1, E1, P & θ are present when
Anvil singulation method is used and not present for saw
singulation.
10. Depending on the method of lead termination at the edge of the
package, a maximum 0.15mm pull back (L1) maybe present. L
minus L1 to be equal to or greater than 0.3mm.
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ISL6430CR.PDF ] | |
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