4

ML6633

FUNCTIONAL DESCRIPTION

The ML6633 accepts ECL input signals and generates a

high speed, high accuracy output current which is

independent of supply voltage variations. The output

current is programmable up to 82mA.

The ECL input stage is a standard NPN differential pair

with a common mode range of between 1V and 4.5V with

a +5V supply. With this common mode range it is possible

to convert the ECL inputs into TTL. If the ECLN input is

biased up to the TTL switching level, the ECLP pin can be

driven by a TTL or CMOS output. Figure 1b shows a circuit

implementing this technique. This circuit may degrade

pulse width distortion and should be checked for

acceptable performance in this configuration.

Output current to the LED is set by connecting the

appropriate resistance from RTSET to ground. The high

level output voltage at RTSET will be 2.0V. The current in

the external resistor will be equal to the current through

the LED. The output current with RTSET set to 26.1Wwill

be:

IHIGH

V

RTSET

2

(1)

IHIGH

V

mA

.

==

2

26 1

75

Ω

Figure 1. Typical Applications

RTSET

GND

5V

VIN+

VIN–

ECLP

ECLN

b) ECL-to-TTL Conversion

5V

5V

NC

NC

RTSET

GND

5V

TTLIN

ECLP

ECLN

5V

NC

NC