ISL90843UIU1027Z 데이터 시트보기 (PDF) - Intersil

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ISL90843UIU1027Z

Low Noise, Low Power, I2C® Bus, 256 Taps

Intersil 

ISL90843

Typical Performance Curves (Continued)

1.50

1.00

0.50

5.5V

0.00

2.7V

-0.50

-1.00

-1.50

-40

-20

0

20

40

60

80

TEMPERATURE (°C)

FIGURE 7. END TO END RTOTAL % CHANGE vs

TEMPERATURE

20

10

0

-10

-20

32

82

132

182

232

TAP POSITION (DECIMAL)

FIGURE 8. TC FOR VOLTAGE DIVIDER MODE IN ppm

Signal at Wiper (Wiper Unloaded)

SCL

Wiper Movement Mid Point

From 80h to 7fh

FIGURE 9. MIDSCALE GLITCH, CODE 80h TO 7Fh (WIPER 0)

Principles of Operation

The ISL90843 is an integrated circuit incorporating four

DCPs with their associated registers, and an I2C serial

interface providing direct communication between a host

and the potentiometers.

DCP Description

Each DCP is implemented with a combination of resistor

elements and CMOS switches. The physical ends of each

DCP are equivalent to the fixed terminals of a mechanical

potentiometer (RH and RL pins). The RW pin of each DCP is

connected to intermediate nodes, and is equivalent to the

wiper terminal of a mechanical potentiometer. The position

of the wiper terminal within the DCP is controlled by an 8-bit

volatile Wiper Register (WR). Each DCP has its own WR.

When the WR of a DCP contains all zeroes (WR<7:0>: 00h),

its wiper terminal (RW) is closest to its “Low” terminal (RL).

When the WR of a DCP contains all ones (WR<7:0>: FFh),

its wiper terminal (RW) is closest to its “High” terminal (RH).

7

Signal at Wiper

(Wiper Unloaded Movement

From ffh to 00h)

FIGURE 10. LARGE SIGNAL SETTLING TIME

As the value of the WR increases from all zeroes (00h) to all

ones (255 decimal), the wiper moves monotonically from the

position closest to RL to the closest to RH. At the same time,

the resistance between RW and RL increases monotonically,

while the resistance between RH and RW decreases

monotonically.

While the ISL90843 is being powered up, all four WRs are

reset to 80h (128 decimal), which locates RW roughly at the

center between RL and RH.

The WRs can be read or written directly using the I2C serial

interface as described in the following sections. The I2C

interface Address Byte has to be set to 00hex, 01hex,

02hex, and 03hex to access the WR of DCP0, DCP1, DCP2,

and DCP3 respectively.

I2C Serial Interface

The ISL90843 supports a bidirectional bus oriented protocol.

The protocol defines any device that sends data onto the

FN8095.2

March 29, 2006

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