by Dave Roberts [dave.roberts at BTINTERNET.COM]
I found that I could not raise TEST to Vihh ( 13 V ). If I did, it consumed excessive current.
This appeared as a low impedance resistive path to ground from TEST. Devices from different batches exhibited it.
I checked the datasheet, found internal inconsistencies and in the absence of other avenues, doubted the spec.
The answer was that voltage overshoot on the rising edge of TEST killed the chips. My designs use serial programming in the target hardware. Previous designs such as for the 14000 worked fine. This time wiring effects caused the overshoot. Specifically, the rising edge overshot by 3V for about 10 nsec - must use slower circuits in the future !
Also, for reference, the datasheet is in error in the following ways
Programing Datasheet DS30274B dated 1998
Main Device Datasheet DS30289A dated 1998
|file: /Techref/microchip/icsp17c766-dr.htm, 2KB, , updated: 2001/10/18 11:34, local time: 2019/4/25 18:51,
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