ISL8009AEVAL1Z Datasheet, PDF (1/5 Pages) Intersil Corporation – 1.5A Synchronous Buck Regulator with Integrated MOSFETs

ISL8009AEVAL1Z: 1.5A Synchronous Buck
®
Regulator with Integrated MOSFETs
Application Note
October 9, 2008
AN1388.1
Description
The ISL8009AEVAL1Z kit is intended for use by individuals
with requirements for Point-of-Load applications sourcing
from 2.7V to 5.5V. The ISL8009EVAL1Z evaluation board
demonstrates the performance of the ISL8009A low
quiescent current mode converter.
The ISL8009A is offered in a 2mmx3mm 8 Ld DFN package
with 1mm maximum height. The complete converter
occupies less than 1cm² area.
Key Features
• High Efficiency Synchronous Buck Regulator With up to
95% Efficiency
• 2ms Reset Timer
• Soft Discharge Output Cap During Disable
• 2.7V to 5.5V Supply Voltage
• 3% Output Accuracy Over-Temperature/Load/Line
• 1.5A Guaranteed Output Current
• 17µA Quiescent Supply Current in PFM Mode
• Selectable Forced PWM Mode and PFM Mode
• Less Than 1µA Logic Controlled Shutdown Current
• 90% Maximum Duty Cycle for Lowest Dropout
• Internal Current Mode Compensation
• Internal Digital Soft-Start
• Peak Current Limiting, Short Circuit Protection
• Over-Temperature Protection
• Enable
• Small 8 Ld 2mmx3mm DFN
• Pb-Free (RoHS Compliant)
Recommended Equipment
The following materials are recommended to perform
testing:
• 0V to 10V power supply with at least 5A source current
capability, battery, notebook AC adapter
• Two electronic loads capable of sinking current up to 5A
• Digital Multimeters (DMMs)
• 100MHz quad-trace oscilloscope
• Signal generator
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_OUT
Evaluating the Other Output Voltage
The ISL8009AEVALIZ kit output is preset to 1.8V; however,
output voltages can be adjusted from 0.8V to 3.3V by
following Equations 1 and 2:
V_OUT
=
0.8
⎛
⎜1
⎝
+
RR_{-----12- ⎠⎟⎞}
(EQ. 1)
Let’s set R₁= 124kΩ:
R₂
=
----------⁽--^R-----¹---⁾----------
⎛
⎝
-^V---₀-^O---_.-^U₈----^T--_⎠⎞
–
1
(EQ. 2)
If desired output is 0.8V then short R₁ and open R₂.
Mode Control
The ISL8009A 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 forced PWM mode. The
forced PWM mode remains the fixed PWM frequency at light
load instead of entering the skip mode.
TABLE 1. SWITCH 1 SETTINGS
SW1
SKIP
FUNCTION
1
PWM
Fixed PWM frequency at light load
3
PFM
Force continuous mode
SW2
1
3
ENABLE
OFF
ON
ON/OFF CONTROL
Disable V_OUT
Enable V_OUT
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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