ISL85402 Datasheet, PDF (1/18 Pages) Intersil Corporation – 2.5A Regulator with Integrated High-Side MOSFET for Synchronous Buck or Boost Buck Converter

2.5A Regulator with Integrated High-Side MOSFET for
Synchronous Buck or Boost Buck Converter
ISL85402
The ISL85402 is a synchronous buck controller with a 125mΩ
high-side MOSFET and low-side driver integrated. The ISL85402
supports a wide input voltage range from 3V to 36V. Regarding the
output current capability from the thermal perspective, the
ISL85402 can typically support continuous load of 2.5A under
conditions of 5V V_OUT, V_IN range of 8V to 30V, 500kHz, +85°C
ambient temperature with still air. For any specific application, the
actual maximum output current depends upon the die temperature
not exceeding +125°C with the power dissipated in the IC, which is
related to input voltage, output voltage, duty cycle, switching
frequency, board layout and ambient temperature, etc. Refer to
“Output Current” on page 13 for more details.
The ISL85402 has 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 pre-regulator followed by a buck
controlled by the same IC, which greatly expands the operating
input voltage range down to 3V or lower (Refer to “Typical
Application Schematic III - Boost Buck Converter” on page 5).
The ISL85402 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; besides that, the hiccup overcurrent
mode is also implemented to guarantee reliable operations
under harsh short conditions.
The ISL85402 has comprehensive protections against various faults
including overvoltage and over-temperature protections, etc.
Features
• Ultra Wide Input Voltage Range 3V to 36V
• Optional Mode Operation
- Forced PWM Mode
- Selectable PFM with Programmable PFM/PWM Boundary
• 300µA IC Quiescent Current (PFM, No Load); 180µA Input
Quiescent Current (PFM, No Load, V_OUT Connected to
AUXVCC)
• Less than 3µA Standby Input Current (IC Disabled)
• Operational Topologies
- Synchronous Buck
- Non-Synchronous Buck
- Two-Stage Boost Buck
• 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
BOOT
VCC
ILIMIT
SS
ISL85402 _PHASE
LGATE
PGND
EXT_BOOST
FS
SGND
FB
COMP
FIGURE 1. TYPICAL APPLICATION
September 29, 2011
1
FN7640.0
VOUT
100
95
90
85
80
75
70
65
60
55
50
0.1m
6V V_IN
12V V_IN
24V V_IN
36V V_IN
1m
10m
100m
LOAD CURRENT (A)
1.0 2.5
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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