Texas Instruments SN75494 aka SN27423, SN27914


The SN75494 provides the same basic function as the SN75492 but with some key differences:

* Operates from lower Vcc voltages, as low as 3.2V
* The SN75494 provides access to the predriver collectors via the Vcc pin to allow good saturation of the output transistors
* An enable input is provided to allow display blanking

The SN75494 is preferred on designs running on 3 batteries and is typically found in early designs with additional segment drivers (TMS0120).


SR-10 and other early LED calculators

Technical Specification

Item Min Typ Max Unit Comments
VDD -8.1 -7.2 -6.6 V  
VCC 3.2   -3.2 V referenced to VSS
IL  250     mA VI=6.5 V, VO=3.5 V
IL       mA  
VI-VD       V  
VI-VD       V  


The SN75494 uses a standard DIP-16 package.

Pin Description

Pin IO Function Pin IO Function
1 V VSS 16 V VCC
2 I Digit input 1 15 O Digit output 6
3 O Digit output 1 14 I Digit input 6
4 O Digit output 2 13 O Digit output 5
5 I Digit input 2 12 I Digit input 5
6 O Digit output 3 11 O Digit output 4
7 I Digit input 3 10 I Digit input 4
8 V VDD 9 I Enable drivers


If you have additions to the above datasheet please email:

Joerg Woerner, February 02, 2001. No reprints without written permission.