7

Maxim Integrated

Digitally-Programmed, Dual

2nd-Order Continuous Lowpass Filter

MAX270/MAX271

Pin Description (continued)

MAX271

X = Pin has no function in this mode.

Note: All digital input levels are TTL and CMOS compatible, unless otherwise noted.

PIN

NAME

FUNCTION, FP MODE (MODE = GND OR V-)

FUNCTION, FP MODE (MODE = GND OR V+)

1

T/H OUT

Track-and-Hold Output

2

V+

Positive Supply Voltage

3

OUTA

Filler A Signal Output

4

SHDN

—

SHUTDOWN Control. A low level disconnects outputs

and places device into shutdown mode

5

INA

Filter A Signal Input

6

V-

Negative Supply Voltage

7

INB

Filter B Signal Input

8

MODE

Selects FP mode when connected to GND or V- and pin-strap mode when connected to V+.

9

OUTB

Filter B Signal Output

10

GND

Ground

11

T/H A/B

—

Track-and-Hold Input Control. A high/low level internally

connects OUTNOUTB to input of Track-and-Hold

12

WR

WRITE Control Input. A low level writes data

D0-D6 program memory addressed by A1, A0

(or performs function as described for address

inputs). High level latches data.

—

13

T/H EN

X

Track-and-Hold Output Control. Low level disconnects

T/H OUT. Connect pin high for normal operation

14

CS

Chip Select Input. Must be low for WR input to

be recognized.

—

15, 16

A1, A0

Address and FP Control Inputs.

0, 0 Programs fC, filter A

0, 1 Programs fC, filter B

1,0 Controls T/H functions:

D0 performs T/H En pin function

D1 performs T/H A/B pin function.

1,1 Controls device shutdown:

D0 performs SHDN pin function

Note: The WR pin must be strobed low to initiate

a program/function (Figure 2).

—

17-23

D0–D6

7-bit Data Inputs. Allows programming of

128 cutoff frequencies (also performs control

functions as described above).

7-bit Data Inputs. Program memory latches are trans-

parent in this mode. Connect pins high or low to

program filters A and B simultaneously to the same fC.

24

T/H

Track-and-Hold Control. Low level causes T/H OUT to track selected filter output. Filter output level held at

T/H OUT synchronous with T/H rising transition.