Intersil ISL8014AEVAL2Z Application Note

ISL8014AEVAL2Z: 4A Low Quiescent Current 1MHz
High Efficiency Synchronous Buck Regulator

Description

The ISL8014AEVAL2Z kit is intended for use by
individuals with requirements for Point-of-Load
applications sourcing from 2.7V to 5.5V. The
ISL8014AEVAL2Z evaluation board demonstrates the
performance of the ISL8014A low quiescent current
mode converter.
The ISL8014A is offered in a 4mmx4mm 16 Ld QFN
package with 1mm maximum height. The ISL8014A is
pin-to-pin compatible to the ISL8013A. The complete
converter occupies less than 0.4in

Key Features

• High Efficiency Synchronous Buck Regulator with up
to 95% Efficiency
• Power-Good (PG) Output with 1ms Delay
• 2.7V to 5.5V Supply Voltage
• 3% Output Accuracy Over-Temperature/Load/Line
• 4A Guaranteed Output Current
• Start-up with Pre-biased Output
• Internal Digital Soft-Start - 1ms
• Soft-Stop Output Discharge During Disabled
• 35µA Quiescent Supply Current in PFM Mode
• Selectable Forced PWM Mode and PFM Mode
• External Synchronization up to 4MHz
• Less than 1µA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle for Lowest Dropout
• Internal Current Mode Compensation
• Peak Current Limiting and Hiccup Mode Short Circuit
Protection
• Over-Temperature Protection

Recommended Equipment

The following materials are recommended to perform
testing:
• 0V to 10V Power Supply with at least 5A Source
Current Capability or 5V Battery
• Electronic Loads Capable of Sinking Current Up to 5A
• Digital Multimeters (DMMs)
• 100MHz Quad-trace Oscilloscope
• Signal Generator
December 16, 2009
AN1366.3
2
area.
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774

Application Note 1366

Quick Setup Guide

1. Ensure that the circuit is correctly connected to the
supply and loads prior to applying any power.
2. Connect the bias supply to VIN. Plus terminal to P4
(VIN) and negative return to P5 (GND).
3. Verify that position is ON for SW1.
4. Turn on the power supply.
5. Verify the output voltage is 1.8V for V

Evaluating the Other Output Voltage

The ISL8014AEVAL2Z kit output is preset to 1.8V;
however, output voltages can be adjusted from 0.8V to
3.3V using Equations 1 and 2:
⎛ ⎞
R
1
⎜ ⎟
------ -
V = 0.8 1 +
OUT
⎝ R ⎠
2
Let's set R = 124kΩ
1
( )
R
1
R ------------------------------ -
=
2
V
⎛ ⎞
OUT
--------------- -
– 1
⎝ ⎠
0.8
Note: If desired output is 0.8V, then short R
R .
2

Mode Control

The ISL8014A has a SKIP pin that controls the operation
mode. When the SKIP pin is driven to low or shorted to
ground, the regulator operates in a PFM mode. Set SKIP
pin high forced PWM mode. The controller remains in the
fixed PWM frequency at light load instead of entering the
skip mode. In an application where situations require the
ISL8014A regulator to sink more than 2A valley inductor
current, it is recommended to operate in PFM to avoid
any possible over stress.
TABLE 1. SWITCH 1 SETTINGS
SW1 ENABLE
1 OFF
3 ON
SW2 SKIP
1 PWM
3 PFM
|
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2007, 2008, 2009. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
OUT
(EQ. 1)
(EQ. 2)
and open
1
ON/OFF CONTROL
Disable V
OUT
Enable V
OUT
FUNCTION
Fixed PWM frequency at light load
Force continuous mode