ISL85403 データシートの表示（PDF） - Renesas Electronics

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ISL85403

2.5A Regulator with Integrated High-side MOSFET for Synchronous Buck or Boost Buck Converter

Renesas Electronics 

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ISL85403

2.5A Regulator with Integrated High-side MOSFET for Synchronous Buck or

Boost Buck Converter

FN8631

Rev 1.00

March 13, 2015

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 VIN drops below VOUT, 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 VOUT). 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, VOUT 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

BOOT

VCC

ILIMIT

ISL85403

ISL85403 PHASE

SS

LGATE

EXT_BOOST

FS

SGND

PGND

FB

COMP

FIGURE 1. TYPICAL APPLICATION

VOUT

100

95

6V VIN

90

85

12V VIN

80

75

36V VIN

70

24V VIN

65

60

55

50

0.1m

1m

10m

100m

LOAD CURRENT (A)

1.0 2.5

FIGURE 2. EFFICIENCY, SYNCHRONOUS BUCK, PFM MODE,

VOUT 5V, TA = +25°C

FN8631 Rev 1.00

March 13, 2015

Page 1 of 24

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