THS1041

SLAS289C − OCTOBER 2001 − REVISED OCTOBER 2004

27

www.ti.com

PRINCIPLES OF OPERATION

digital control registers

The THS1041 contains two clamp registers and a control register for user programming of THS1041 operation.

Binary data can be written into these registers by using pins I/O0 to I/O9 and the WR and OE pins (see the

previous section). In input mode, the two I/O bus MSBs are address bits, 00 addressing clamp register 1, 01

clamp register 2, and 10 the control register. The clamp registers and control registers are write only registers,

and stored values cannot be read on the I/O data bus.

Table 2. Register Map

ADDRESS

DESCRIPTION

DEF

W

BIT

ADDRESS

I/O[9:8]

DESCRIPTION

DEF

(HEX)

W

B7

B6

B5

B4

B3

B2

B1

B0

00

Clamp register 1

00

W

DAC[7]

DAC[6]

DAC[5]

DAC[4]

DAC[3]

DAC[2]

DAC[1]

DAC[0]

01

Clamp register 2

00

W

DAC[9]

DAC[8]

10

Control register

01

W

CLDIS

TWOC

CLINT

PDWN

PGA[2]

PGA[1]

PGA[0]

11†

Reserved†

† Do not write to register 11

Table 3. Register Contents

REGISTER

BIT NO

BIT NAME(S)

DEFAULT

DESCRIPTION

2:0

PGA[2:0]

001

PGA gain:

000 = 0.5

001 = 1.0 (default value)

010 = 1.5

011 = 2.0

100 = 2.5

101 = 3.0

110 = 3.5

111 = 4.0

Control register

I/O[9:8] = 10

3

PDWN

0

Power down

0 = THS1041 powered up

1 = THS1041 powered down

I/O[9:8] = 10

4

CLINT

0

Clamp voltage internal/external

0 = external analog clamp voltage from CLAMPIN pin

1 = from onboard DAC (see clamp register)

5

TWOC

0

Output format

0 = unsigned binary

1 = twos complement

6

CLDIS

0

CLAMPOUT pin disable (for power saving)

0 = Enable

1 = Disable

7

Unused

Clamp register 1

I/O[9:8] = 00

7:0

DAC[7:0]

0

Clamp DAC voltage

(DAC[0] = LSB.)

DAC[9:0] = 00h: Clamp voltage = REFB

DAC[9:0] = 3Fh: Clamp voltage = REFT

Clamp register 2

7:2

Unused

Clamp register 2

I/O[9:8] = 01

1:0

DAC[9:8]

0

Clamp DAC voltage

(DAC[9] = MSB)