ISL85403 Datasheet, PDF (1/24 Pages) Intersil Corporation – Non-inverting single inductor buck boost

DATASHEET
2.5A Regulator with Integrated High-side MOSFET for
Synchronous Buck or Boost Buck Converter
ISL85403
The ISL85403 is a 40V, 2.5A synchronous buck or boost buck
controller with a high-side MOSFET and low-side driver
integrated. In buck mode, the ISL85403 supports a wide input
range of 3V to 40V. In boost-buck mode, the input range can
be extended down to 2.5V and output regulation can be
maintained when V_IN drops below V_OUT, enabling sensitive
electronics to remain on in low input voltage conditions.
The ISL85403 has a flexible selection of operation modes of
forced PWM mode and PFM mode. In PFM mode, the
quiescent input current is as low as 180µA (AUXVCC connected
to V_OUT). The load boundary between PFM and PWM can be
programmed to cover wide applications.
The low-side driver can be either used to drive an external low-side
MOSFET for a synchronous buck or left unused for a standard
non-synchronous buck. The low-side driver can also be used to
drive a boost converter as a preregulator followed by a buck
controlled by the same IC, which greatly expands the operating
input voltage range down to 2.5V or lower (Refer to “Typical
Application Schematic III - Boost Buck Converter” on page 6).
The ISL85403 offers the most robust current protections. It uses
peak current mode control with cycle-by-cycle current limiting.
It is implemented with frequency foldback under current limit
condition; also, the hiccup overcurrent mode is also
implemented to guarantee reliable operations under harsh
short conditions.
The ISL85403 has comprehensive protections against various
faults including overvoltage and over-temperature protections,
etc.
Related Literature
• AN1960, “ISL85403DEMO1Z Demonstration Board User
Guide”
• UG010, “ISL85403EVAL2Z Evaluation Board User Guide”
Features
• Buck mode: input voltage range 3V to 40V (refer to “Input
Voltage” on page 15 for more details)
• Boost mode expands operating input voltage lower than
2.5V (refer to “Input Voltage” on page 15 for more details)
• Selectable forced PWM mode or PFM mode
• 300µA IC quiescent current (PFM, no load); 180µA input
quiescent current (PFM, no load, V_OUT tied to AUXVCC)
• Less than 5µA (MAX) shutdown input current (IC disabled)
• Operational topologies
- Synchronous buck
- Non-synchronous buck
- Two-stage boost buck
- Non-inverting single inductor buck boost
• Programmable frequency from 200kHz to 2.2MHz and
frequency synchronization capability
• ±1% tight voltage regulation accuracy
• Reliable overcurrent protection
- Temperature compensated current sense
- Cycle-by-cycle current limiting with frequency foldback
- Hiccup mode for worst case short condition
• 20 Ld 4x4 QFN package
• Pb-free (RoHS compliant)
Applications
• General purpose
• 24V bus power
• Battery power
• _{Point-of-load}
• Embedded processor and I/O supplies
PGOOD
EN
VIN
VIN
MODE
SYNC
AUXVCC
ISL85403
VCC
ISL85403
ILIMIT
SS
BOOT
PHASE
LGATE
EXT_BOOST
FS
SGND
PGND
FB
COMP
FIGURE 1. TYPICAL APPLICATION
March 13, 2015
1
FN8631.1
VOUT
100
95
6V V_IN
90
85
12V V_IN
80
75
36V V_IN
70
24V V_IN
65
60
55
50
0.1m
1m
10m
100m
1.0 2.5
LOAD CURRENT (A)
FIGURE 2. EFFICIENCY, SYNCHRONOUS BUCK, PFM MODE,
V_OUT 5V, T_A = +25°C
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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