218 Analog Measurement Processor

Refer to Figure 2-2 for an overall picture of the Analog Measurement Processor chip and its peripheral circuits. Table 2-1 describes Analog Measurement Processor chip signal names.

The Analog Measurement Processor (A1U1) is a 68-pin CMOS device that, under control of the Main Processor (A1U6), performs the following functions:

• Input signal routing

• Input signal conditioning

• Range switching

• Active filtering of dc-type measurements. The active filter is disabled for fast reading rate measurements.

• Support for direct volts, direct current, true rms alternating volts, true rms alternating current, ohms, frequency, and continuity/diode test functions.

Two separate signal paths are used, one for dc/ohms and one for ac. For dc, the 3 V range and below are coupled directly to the a/d converter; higher voltages are attenuated. For ohms, the dc circuitry is augmented with an internal ohms source voltage regulator controlled through an extra set of switches. For ac, inputs are routed through the ac buffer, with attenuation being controlled by the a/d converter.

The a/d converter uses a modified dual-slope minor cycle method. The basic measurement unit, a minor cycle, consists of a fixed time integrate period for the unknown input, a variable reference integrate period, a variable hold period, and various short transition periods. A minor cycle period equals 25 ms.

3"

cd 3

Frequency Counter

RRS = Reference Resistor Sence

RMS Converter

Frequency Counter

RRS Lo

RRS Hi RRS Lo

Active Filter

UlAnalog Measurement Processor*

Digital Section

RRS = Reference Resistor Sence

A/D Ref

Not all U1 switches are shown here. Refer to the schematic diagram in Chapter 8.

DIGR

■ Serial Communication 1

Table 2-1. Analog Measurement Processor Pin Name Description

Pin

Name

Description

1

VDD

+5 V supply

2

ACBO

AC buffer output

3

AIN

Amps input

4

AGND2

Analog ground #2

5

ACR4

AC buffer range 4

6

ACR3

AC buffer range 3

7

ACR2

AC buffer range 2

8

ACR1

AC buffer range 1

9

VSSACR

-5 V supply for AC ranging

10

(not used)

11

LO

A/D converter low input

12

GRD

Guard

13

RRS

Reference resistor sense for ohms

14

V4

Tap #4 on the DCV input divider/ohms reference network

15

V3

Tap #3 on the DCV input divider/ohms reference network

16

V1

Tap #1 on the DCV input divider/ohms reference network

17

GRD

Guard

18

V2F

Tap #2 active filter input on the DCV input divider/ohms reference network

19

V2

Tap #2 on the DCV input divider/ohms reference network

20

GRD

Guard

21

V0

Tap #0 on the DCV input divider/ohms reference network

22

GRD

Guard

23

OVS

Ohms and volts sense input

24

GRD

Guard

25

AGND1

Analog ground #1

26

(not used)

27

DGND

Digital ground

28

FC0

Function control #0

29

FC1

Function control #1

30

FC2

Function control #2

31

FC3

Function control #3

32

FC4

Function control #4

33

FC5

Function control #5

34

FC6

(not used)

35

FC7

(not used)

36

OSCIN

Crystal oscillator input

37

OSCO

Crystal oscillator output

38

MRST

Master reset

39

AS

Analog send

40

AR

Analog receive

41

SK

Serial clock

42

CS

Chip select

43

BRS

Baud rate select

44

VSS

-5 V

45

INT

Integrator output

46

SUM

Integrator summing node

47

B.1

Buffer output, 100 mV range

48

B.3

Buffer output, 300 mV range

49

B1

Buffer output, 1000 mV range

50

B3

Buffer output, 3 V range

Table 2-1. Analog Measurement Processor Pin Name Description (cont)

Pin

Name

Description

51

VREF+

A/D reference plus

52

VREF-

A/D reference minus

53

RAO

A/D reference amplifier output

54

RA+

A/D reference amplifier noninverting input

55

RA-

A/D reference amplifier inverting input

56

AFO

Active filter output

57

MOF

Megohms filter

58

AFI

Active filter input

59

FAI

Filter amplifier inverting input

60

FAO

Filter amplifier output

61

RMSF

RMS output, filtered

62

ARTN

Analog return

63

(not used)

64

RMSO

RMS converter output

65

BIAS2

Bias input

66

VSSF

-5 V dc, filtered

67

BIAS1

Bias input

68

RMSI

RMS converter input

DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

Get My Free Ebook


Post a comment