ANALOG DEVICES UG-219 Service Manual

Evaluation Board User Guide

One Technology Way • P. O . Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel : [phone] • Fax : [phone] • www.analog.com

UG-219

Evaluating the ADP2370/ADP2371 Buck Regulators

FEATURES

Buck regulator input voltage range: 3.2 V to 15 V
Buck regulator output current: 800 mA
Operating temperature range: −40°C to +125°C

EQUIPMENT NEEDED

Voltage meters, current meters, power supply
Resistive or electronic loads

DOCUMENTS NEEDED

ADP2370/ADP2371 data sheet
UG-220 user guide

DIGITAL PICTURE OF THE EVALUATION BOARD

GENERAL DESCRIPTION

The ADP2370/ADP2371 evaluation boards (ADP2370CP-EVALZ
and ADP2371CP-EVALZ) are used to demonstrate the function­ality of the ADP2370/ADP2371 buck regulators.

Basic electrical performance measurements, such as line and load
regulation, efficiency, and ground current, can be demonstrated
with a few voltage supplies, voltage meters, current meters, and
load resistors.

Complete information about the ADP2370/ADP2371 buck regu­lators is available in the ADP2370/ADP2371 data sheet, which
should be consulted in conjunction with this user guide when
using the evaluation board.

PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.

Figure 1.

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UG-219 Evaluation Board User Guide

TABLE OF CONTENTS

Features .............................................................................................. 1

Equipment Needed ........................................................................... 1

Documents Needed .......................................................................... 1

General Description ......................................................................... 1

Digital Picture of the Evaluation Board ......................................... 1

Revision History ............................................................................... 2

Evaluation Board Hardware and Schematic ................................. 3

Evaluation Board Configuration ................................................ 3

Output Voltage Accuracy Measurements ...................................... 4

REVISION HISTORY

4/12—Revision 0: Initial Version

Line Regulation Measurements ...................................................5

Load Regulation Measurements ..................................................5

Efficiency Measurements .................................................................6

Calculating the Efficiency ............................................................7

Quiescent Current Measurements ..................................................8

Quiescent Current Consumption ...............................................9

Ordering Information .................................................................... 10

Bill of Materials ........................................................................... 10

Related Links ............................................................................... 10

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Evaluation Board User Guide UG-219

ADJ only (5V )

ADJ only (5V )

PG

SW

VOUT

VIN

FSEL

EN

SYNC

VOUT

TB4

U1

ADP2370/ADP2371

VIN

1

FSEL

2

EN

3

PG

6

SW

7

PGND

8

SYNC

4

FB

5

TP4

1

TP9

1

JP2

EN

1

1

2

2

3

3

TP5

1

GND

TB2

R1

10K

TP6

1

JP3

Freq

1

1

2

2

3

3

TP7

1

R2

422K

JP1

Sync

1

1

2

2

3

3

TP1

1

C2

10UF

VIN

TB1

PG

TB3

GND

TB5

R3

80.6K

TP2

1

L1

6.8uH
J1

1 2

TP8

1

C1

10UF

TP3

1

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R1

Pull-up resistor

10 kΩ pull-up resistor for power good (PG).

EVALUATION BOARD HARDWARE AND SCHEMATIC

EVALUATION BOARD CONFIGURATION

The ADP2370/ADP2371 evaluation boards ship with all the
components necessary to perform basic electrical performance
measurements, including the input and output capacitors, buck
inductor, and power-good pull-up resistor. The placement of
the critical components for the buck regulator (inductor and
capacitors) has been optimized for low noise and the smallest
possible footprint.

Figure 2 shows the schematic of the evaluation board configu­ration. Tab le 1 describes the hardware components.

For complete information about the ADP2370/ADP2371 buck
regulators, see the ADP2370/ADP2371 data sheet.

Figure 2. Evaluation Board Schematic

Table 1. Evaluation Board Hardware Components

Component Function Description

U11 Buck regulator ADP2370 or ADP2371 buck regulator.
C1 Input capacitor 10 μF input bypass capacitor required for transient performance.
C2 Output capacitor 10 μF output capacitor required for stability and transient performance.
L12 Inductor 6.8 μH inductor for 3.3 V output at 1.2 MHz.

R2 Resistor 422 kΩ, 1% resistor. With R3, sets the output voltage to 5 V (adjustable version only).
R3 Resistor 80.6 kΩ, 1% resistor. With R2, sets the output voltage to 5 V (adjustable version only).
JP1 Jumper When JP1 is connected to VIN, forced PWM mode is enabled. When JP1 is connected to GND,

JP2 Jumper When JP2 is connected to VIN, the output is enabled. When JP2 is connected to GND, the output

JP3 Jumper When JP3 is connected to VIN, 1.2 MHz operation is selected. When JP3 is connected to GND,

J1 Jumper Connects the FB pin to the buck regulator output (fixed output version only).

1

Component varies depending on the evaluation board model ordered.

2

Inductor value varies depending on the output voltage.

auto mode is enabled. When JP1 is connected to SYNC, an external clock can be used to set the
operating frequency.

is disabled.

600 kHz operation is selected.

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UG-219 Evaluation Board User Guide

OUTPUT VOLTAGE ACCURACY MEASUREMENTS

Figure 3 shows how to connect the evaluation board to a voltage
source and a voltage meter (voltmeter) for basic output voltage
accuracy measurements. A resistor can be used as the load for the
buck regulator. Ensure that the resistor has a power rating adequate
to handle the power that is expected to be dissipated across it. An
electronic load can be used as an alternative. In addition, ensure
that the voltage source can supply enough current for the expected
load levels.

Follow these steps to connect the evaluation board to a voltage
source and voltage meter:

1. Connect the negative terminal (−) of the voltage source

to the GND pad (TB2) on the evaluation board.

2. Connect the positive terminal (+) of the voltage source

to the VIN pad (TB1) on the evaluation board.

3. Connect a load between the VOUT pad (TB4) and one

of the GND pads on the evaluation board.

4. Connect the negative terminal (−) of the voltmeter to one

of the GND pads on the evaluation board.

5. Connect the positive terminal (+) of the voltmeter to the

VOUT pad (TP7) on the evaluation board.

6. Connect a jumper between Pin 1 and Pin 2 of JP2 to enable

the buck regulator.

7. Connect a jumper between Pin 3 and Pin 2 of JP1 to enable

auto mode.

8. Connect a jumper between Pin 1 and Pin 2 of JP3 to enable

1.2 MHz operation.

9. Turn on the voltage source.

If the load current is large, connect the voltage meter as close to
TB4 as possible to reduce the effects of IR drops.

LOAD

VOLTMETER

1.99711

–

+

VOLTAGE SOURCE

–

Figure 3. Buck Regulator Output Voltage Regulation Measurement Setup

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+

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