TLC04/MF4A-50, TLC14/MF4A-100

BUTTERWORTH FOURTH-ORDER LOW-PASS

SWITCHED-CAPACITOR FILTERS

SLAS021A – NOVEMBER 1986 – REVISED MARCH 1995

2

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

functional block diagram

6

AGND

8

FILTER OUT

5

φ2

φ1

Butterworth

Fourth-Order

Low-Pass Filter

Nonoverlapping

Clock Generator

2

CLKR

1

CLKIN

3

LS

Level Shift

FILTER IN

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

AGND

6

I

Analog ground. The noninverting input to the operational amplifiers of the Butterworth fourth-order low-pass filter.

CLKIN

1

I

Clock in. CLKIN is the clock input terminal for CMOS-compatible clock or self-clocking options. For either option,

LS is at VCC – . For self-clocking, a resistor is connected between CLKIN and CLKR and a capacitor is connected

from CLKIN to ground.

CLKR

2

I

Clock R. CLKR is the clock input for a TTL-compatible clock. For a TTL clock, LS is connected to midsupply and

CLKIN can be left open, but it is recommended that it be connected to either VCC+ or VCC – .

FILTER IN

8

I

Filter input

FILTER OUT

5

O

Butterworth fourth-order low-pass filter output

LS

3

I

Level shift. LS accommodates the various input clocking options. For CMOS-compatible clocks or self-clocking,

LS is at VCC – and for TTL-compatible clocks, LS is at midsupply.

VCC+

7

I

Positive supply voltage terminal

VCC –

4

I

Negative supply voltage terminal