ISL78220ANEZ Datasheet, PDF (1/22 Pages) Intersil Corporation – 6-Phase Interleaved Boost PWM Controller with Light Load Efficiency Enhancement

6-Phase Interleaved Boost PWM Controller with Light
Load Efficiency Enhancement
ISL78220
The ISL78220 6-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 ISL78220 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 by 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 ISL78220 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 ISL78220 can output a clock signal for expanding
operation to 12 phases, which offers high system flexibility.
The threshold-sensitive enable input is available to accurately
coordinate the start-up of the ISL78220 with any other voltage
rail.
Features
• Peak current mode PWM Control with adjustable slope
compensation
• Precision resistor/DCR current sensing
• 2-, 3-, 4- or 6-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 package (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
Related Literature
• See AN1726, “ISL78220EVAL1Z: 6-Phase Interleaved
Synchronous Boost Converter”
0.98
WITH PHASE DROPPING
0.97
0.96
WITHOUT PHASE DROPPING
0.95
0.94
0.93
0.92
0.91
0.90
6V INPUT, 12V OUTPUT
0.89
SYNCHRONOUS BOOST
0.88
0
5
10
15
20
25
30
OUTPUT CURRENT (A)
FIGURE 1. EFFICIENCY vs OUTPUT CURRENT vs PHASE DROPPING MODE
December 24, 2013
1
FN7688.3
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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