MAX1460 Просмотр технического описания (PDF) - Maxim Integrated

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MAX1460

Low-Power, 16-Bit Smart ADC

Maxim Integrated 

MAX1460

Low-Power, 16-Bit Smart ADC

Table 4. Test System Commands

COMMAND

Write a calibration coefficient into a DSP register.

Block-Erase the entire EEPROM (writes “0” to all 128 bits).

Write “1” to a single EEPROM bit.

NOOP (NO-OPeration)

Start Conversion command. The registers are not updated with EEPROM values.

SDIO and SDO are enabled as DSP outputs.

Start Conversion command. The registers are updated with EEPROM values. SDIO

and SDO are enabled as DSP outputs.

Start Conversion command. The registers are not updated with EEPROM values.

SDIO and SDO are disabled.

Start Conversion command. The registers are updated with EEPROM values. SDIO

and SDO are disabled.

Reserved

HEX CODE

1 hex

4 hex

2 hex

0 hex

8 hex

C3 C2 C1 C0

0001

0100

0010

0000

1000

A hex

1010

C hex

1100

E hex

1110

3, 5, 6, 7, 9, B, D, F hex - - - -

Table 5. DSP Calibration Coefficient Registers

COEFFICIENT

Gain

G1

G2

Of0

Of1

Of2

DOFF

REGISTER

ADDRESS

1

2

3

4

5

6

7

FUNCTION

Gain correction

Linear TC gain

Quadratic TC gain

Offset correction

Linear TC offset

Quadratic TC offset

Output midscale pedestal

RANGE

-32768 to +32767

-1.0 to +0.99997

-1.0 to +0.99997

-1.0 to +0.99997

-1.0 to +0.99997

-1.0 to +0.99997

-32768 to +32767

FORMAT

Integer

Fraction

Fraction

Fraction

Fraction

Fraction

Integer

Writing to the DSP Registers

Command 1 hex writes calibration coefficients from the

test system directly into the DSP registers. Tester com-

mands 8 hex and C hex cause the MAX1460 to start a

conversion using the calibration coefficients in the reg-

isters. This direct use of the registers speeds calibration

and compensation because it does not require EEPROM

write-access time. Bringing RESET low clears the DSP

registers, so the test system should always write to the

registers and start a conversion in a single command tim-

ing sequence.

As shown in Table 5, seven registers hold the calibration

coefficients of the characteristic equation [DOUT = Gain

(1+G1T + G2T2) (Signal + Of0 + Of1T + Of2T2) + DOFF]

implemented by the MAX1460 DSP. All of th registers are

16-bit, two’s complement coding format. When a register

is interpreted as an integer, the decimal range is from

-32768 (8000 hex) to +32767 (7FFF hex). Fractional

coefficient values range from -1.0 (8000 hex) to +0.99997

(7FFF hex).

The register at address 0 is called the Configuration

Register. It holds the coarse offset, PGA gain, Op Amp

Power-Down, temperature-sensor offset, repeat mode,

and reserved bits, as shown in Table 6. The functionality

of the coarse offset, PGA gain, and temperature-sensor

bits are described in the Analog Front End section.

The Op Amp Power-Down bit enables the uncommitted

op amp when set. The repeat-mode bit is tested by the

last instruction of the DSP microcode, and, if set, imme-

diately initiates another conversion cycle. The Maxim

reserved bits should not be altered.

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