Range Decoder - HP 8112A Operating, Programming And Servicing Manual

Note
10.3-22 Servicing the Timing and
Slope Generators
5. Verify that the voltages at U301 pins 11/15 are at REF voltage
(typ. +1.85 V)
6. Verify that the voltage at U301 pin 13 is at TTL LOW level (typ.

Range Decoder

1. Check the range decoder against Table 10.3-16.
Table 10.3-16. Range Decoder Truth Table
U
Slope Range Transition Time
5.5
1 ns - 99.9 ns
2 50
ns - 999 ns
3
4
5 5 0 ps - 999 ps
6 0.5 ms - 9.99 ms
7 50
ms - 99.9 ms
Area
Only in Self-Test
LEE and TRE must be in the same range. See transition modes
operating section)
2. Should values of LEE and TRE be selected that overlay in an
overlap region, the microprocessor selects the nearer range.
Example. If LEE and TRE are changed from 100 ns to 750ns, Range
2 will be selected and if they are changed from 100 11s to 750 ns,
Range 3 will be selected.
9
2 5 6
R2 R3
Ext
H
L H H
H
H L H
H
H L L
H L L L
H L L L
H L
L L
L
H L L
1 0
12 15 16 19
R4 R5 R6
L
H H
L
H H
L
H H
L
H H
L
L H
L
L L
L
L L
1 3
H