ISL85403 データシートの表示（PDF） - Intersil

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ISL85403

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

Intersil 

ISL85403

Functional Pin Descriptions (Continued)

PIN NAME PIN #

DESCRIPTION

SYNC

12 This pin can be used to synchronize two or more ISL85403 controllers. Multiple ISL85403s can be synchronized with their SYNC

pins connected together. 180° phase shift is automatically generated between the master and slave ICs.

The internal oscillator can also lock to an external frequency source applied on this pin with square pulse waveform (with frequency

10% higher than the IC’s local frequency, and pulse width higher than 150ns). Range: 0V to 5.5V.

This pin should be left floating if not used.

LGATE

13 In synchronous buck mode, this pin is used to drive the lower side MOSFET to improve efficiency. A 5.1k or smaller value resistor

has to be added to connect LGATE to ground to avoid falsely turn-on of LGATE caused by coupling noise.

In non-synchronous buck when a diode is used as the bottom side power device, this pin should be connected to VCC through a

resistor (less than 5k) before IC start-up to have the low-side driver (LGATE) disabled.

In boost mode, it can be used to drive the boost power MOSFET. The boost control PWM is same with the buck control PWM.

PGND 14 This pin is used as the ground connection of the power flow including driver. Connect it to large ground plane.

BOOT

15 This pin provides bias voltage to the high-side MOSFET driver. A bootstrap circuit is used to create a voltage suitable to drive the

internal N-channel MOSFET. The boot charge circuitries are integrated inside of the IC. No external boot diode is needed. A 1µF

ceramic capacitor is recommended to be used between BOOT and PHASE pin.

VIN 16, 17 Connect the input rail to these pins that are connected to the drain of the integrated high-side MOSFET as well as the source for the

internal linear regulator that provides the bias of the IC. Range: 3V to 40V.

With the part switching, the operating input voltage applied to the VIN pins must be under 40V. This recommendation allows for

short voltage ringing spikes (within a couple of ns time range) due to switching while not exceeding “Absolute Maximum Ratings”

on page 7.

SGND 18 This pin provides the return path for the control and monitor portions of the IC. Connect it to a quiet ground plane.

VCC

19 This pin is the output of the internal linear regulator that supplies the bias for the IC including the driver. A minimum 4.7µF

decoupling ceramic capacitor is recommended between VCC to ground.

AUXVCC

20 This pin is the input of the auxiliary internal linear regulator, which can be supplied by the regulator output after power-up. With

such configuration, the power dissipation inside of the IC is reduced. The input range for this LDO is 3V to 20V.

In boost mode operation, this pin works as boost output overvoltage detection pin. It detects the boost output through a resistor

divider. When voltage on this pin is above 0.8V, the boost PWM is disabled; and when voltage on this pin is below 0.8V minus the

hysteresis, the boost PWM is enabled.

Range: 0V to 20V.

PAD

- Bottom thermal pad. It is not connected to any electrical potential of the IC. In layout it must be connected to PCB ground copper

plane with area as large as possible to effectively reduce the thermal impedance.

Ordering Information

PART NUMBER

(Notes 1, 2, 3)

PART

MARKING

TEMP.

RANGE (°C)

PACKAGE

(RoHS Compliant)

PKG. DWG. #

ISL85403FRZ

85 403FRZ

-40 to +105

20 Ld 4x4 QFN

L20.4x4C

ISL85403DEMO1Z

Compact size demo board for SYNC buck

ISL85403EVAL2Z

Evaluation Board for non-inverting buck-boost configuration

NOTES:

1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.

2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte

tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil

Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.

3. For Moisture Sensitivity Level (MSL), please see product information page for ISL85403. For more information on MSL please see techbrief TB363.

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FN8631.1

March 13, 2015

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