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Número de pieza | ISL78225 | |
Descripción | 4-Phase Interleaved Boost PWM Controller | |
Fabricantes | Intersil Corporation | |
Logotipo | ||
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4-Phase Interleaved Boost PWM Controller with Light
Load Efficiency Enhancement
ISL78225
The ISL78225 4-phase controller is targeted for applications
where high efficiency (>95%) and high power are required. The
multiphase boost converter architecture uses interleaved timing
to multiply channel ripple frequency and reduce input and output
ripple. Lower ripple results in fewer input/output capacitors and
therefore lower component cost and smaller implementation
area.
The ISL78225 has a dedicated pin to initiate the phase dropping
scheme for higher efficiency at light load by dropping phases
based on the load current, so the switching and core losses in the
converter are reduced significantly. As the load increases, the
dropped phase(s) are added back to accommodate heavy load
transients and improve efficiency.
Input current is sensed continuously by measuring the voltage
across a dedicated current sense resistor or inductor DCR. This
current sensing provides precision channel-current balancing,
and per-phase overcurrent protection. A separate totalizing
current limit function provides overcurrent protection for all the
phases combined. This two-stage current protection provides
maximum performance and circuit reliability.
The ISL78225 can also provide for input voltage tracking via the
VREF2 pin. The comparison reference voltage will be the lower of
the VREF2 pin or the internal 2V reference. By using a resistor
network between VIN and VREF2 pin, the output voltage can track
input voltage to limit the output power during automotive cranking
conditions.
The ISL78225 can output a clock signal for expanding operation to
8 phases, which offers high system flexibility. The
threshold-sensitive enable input is available to accurately
coordinate the start-up of the ISL78225 with any other voltage rail.
Features
• Peak current mode PWM control with adjustable slope
compensation
• Precision resistor/DCR current sensing
• 2-, 3- or 4-phase operation
• Adjustable phase dropping/diode emulation/pulse skipping
for high efficiency at light load
• Phase dropping facilitated with companion FET driver
ISL78420 (featuring tri-level input control)
• Adjustable switching frequency or external synchronization
from 75kHz up to 1MHz per phase
• Over-temperature/overvoltage protection
• 2V 1.0% internal reference
• Pb-free 44 Ld 10x10 EP-TQFP (RoHS compliant)
• -40°C to +125°C operating temperature range
• AEC-Q100 qualified
Applications
• Automotive power supplies
- Start/stop DC/DC converter
- Electronic power steering systems (EPAS)
- Fuel pumps
- Injection system
• Audio trunk amplifier power supplies
• Telecom and industrial power supplies
0.98
WITH PHASE DROPPING
0.93
WITHOUT PHASE DROPPING
0.88
0.83
0.78
16V INPUT, 36V OUTPUT
SYNCHRONOUS BOOST
0.73
0 1 2 3 4 5 6 7 8 9 10
OUTPUT CURRENT (A)
FIGURE 1. EFFICIENCY vs OUTPUT CURRENT vs PHASE DROPPING MODE
September 5, 2014
FN7909.4
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2011, 2013, 2014. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
1 page Typical Application 1: 4-Phase Synchronous Boost Converter with Sense Resistor Current
Sensing
VIN
+
VOUT_SEN
VCC EN UGATE
PHASE
DRIVER
PWM1 PWM
LGATE
FS
SS
COMP
FB
VCC VREF2
GND
SLOPE
PLL_COMP
SYNC
CLK_OUT
PWM_INV
PWM_TRI
ISL78225
VIN
NC
NC
ISEN4P
ISEN4N
ISEN2P
ISEN2N
NC
NC
ISEN3P
ISEN3N
ISEN1P
ISEN4P
ISEN4N
ISEN2P
ISEN2N
ISEN3P
ISEN3N
EN
ISEN2P
ISEN2N
PWM2
EN
ISEN3P
ISEN3N
PWM3
EN
ISEN4P
ISEN4N
PWM4
VCC
ISEN1P
ISEN1N
Note: Please see ISL78420 for an Automotive Qualified 100V synchronous boost driver.
Phase 1
Phase 2
Phase 3
Phase 4
VOUT
LOAD
+
5 Page ISL78225
Typical Performance Curves (Continued)
C1 = PWM1, 5V/DIV
C1 = PWM1, 5V/DIV
C2 = PWM2, 5V/DIV
C2 = PWM2, 5V/DIV
C3 = PWM3, 5V/DIV
C4 = CLK_OUT, 5V/DIV
C3 = PWM3, 5V/DIV
C4 = CLK_OUT, 5V/DIV
1µs/DIV
FIGURE 8. WAVEFORMS WITH PWM_INV = GND
1µs/DIV
FIGURE 9. WAVEFORMS WITH PWM_INV = VCC
C1 = PWM1, 5V/DIV
C3 = PWM3, 5V/DIV
C4 = PWM4, 5V/DIV
16V INPUT, 36V AT 10A OUTPUT
C2 = IL1, 5A/DIV
1µs/DIV
FIGURE 10. FULL LOAD WAVEFORMS
C1 = EN, 2V/DIV
C2 = VCC, 5V/DIV
C3 = PGOOD, 5V/DIV
10V INPUT, 36V AT 1A OUTPUT
C4 = VOUT, 20V/DIV
1µs/DIV
FIGURE 11. ENABLE/DISABLE WAVEFORMS
10V INPUT, 10A OUTPUT
C1 = VREF2, 1V/DIV
C4 = VOUT, 20V/DIV
20ms/DIV
FIGURE 12. MODULATING VREF2 INPUT
Submit Document Feedback 11
FN7909.4
September 5, 2014
11 Page |
Páginas | Total 22 Páginas | |
PDF Descargar | [ Datasheet ISL78225.PDF ] |
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