AD8450ASTZ datasheet(35/42 Pages) AD

35 / 42 page

AD8450

Data Sheet

Rev. B | Page 34 of 41

EVALUATION BOARD

INTRODUCTION

Figure 61 is a photograph of the AD8450-EVALZ. The evaluation

board is a convenient standalone platform for evaluating the

major elements of the AD8450 (such as the PGIA and PGDA).

The circuit architecture is particularly suitable for evaluating

PID loop compensation when connected within an operating

charge/discharge system. Four separate loop dynamic networks are

available for constant current charge and discharge, and constant

voltage charge and discharge. The network subcircuits are shown

on the right hand side of the board schematic (Figure 62).

SMA connectors provide shielded access to the highly sensitive

programmable gain instrumentation amplifier (PGIA) and the

programmable gain difference amplifier (PGDA). SMA connectors

ISET and VSET are the constant current and constant voltage

control inputs. The ISMEA and VCTRL outputs, current and

voltage alarm references, and trigger voltages are accessible for

testing. The MODE switch selects either the charge or discharge

option. Figure 62 is a schematic of the AD8450-EVALZ. Table 8

lists and describes the various switches and their functions and

lists the SMA connector I/O.

FEATURES AND TESTS

The AD8450-EVALZ contains many user friendly features to

facilitate evaluation of the AD8450 performance. Numerous

connectors, test loops, and points facilitate the attachment of

scope probes and cables, and I/O switches conveniently exercise

various device options.

TESTING THE AD8450-EVALZ

The schematic item abbreviation TP signifies a test loop. Prior

to testing, install Jumpers TST1 through TST5 and move the

Shunts RUN1 through RUN5 to a single pin to open the

connection. Connect +25 V at AVCC, −5 V at AVEE, and

+5 V at DVCC.

PGIA and Offset

PGIA Gain Test

Apply 10 mV dc across TPISVP and TPISVN. For bench testing,

connect ISVN to ground using an external jumper. Use the

ISGN switch to select the desired PGIA gain option, and measure

the output voltage at TPISMEA or TPIMAX (referenced to

ground). For gains of 26, 66, 133, and 200, the output voltages

are 260 mV, 660 mV, 1.33 V, and 2 V, respectively. Subtract any

residual offset voltages from the output reading before

calculating the gain.

Figure 61. Photograph of the AD8450-EVALZ

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