Browse Prior Art Database

Regulator ByPass Protection Circuit

IP.com Disclosure Number: IPCOM000105445D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 72K

Publishing Venue

IBM

Related People

Dreibelbis, JH: AUTHOR [+3]

Abstract

A circuit is described that allows semiconductor chips with on-chip regulators to function properly when the regulator has been bypassed either intentionally or unintentionally. The regulator bypass protection circuit assures that TTL data input levels are recognized in either the unbypassed or bypassed regulator modes so that the chip performs properly in either mode.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Regulator ByPass Protection Circuit

      A circuit is described that allows semiconductor chips with
on-chip regulators to function properly when the regulator has been
bypassed either intentionally or unintentionally.  The regulator
bypass protection circuit assures that TTL data input levels are
recognized in either the unbypassed or bypassed regulator modes so
that the chip performs properly in either mode.

      A single regulator bypass protection circuit on each protected
chip is capable of controlling the mode of operation of all the TTL
receivers on a chip.  Fig. 1.  shows a bypass detect circuit
(consisting of NFETs N0, N1, N2, N10, PFETs P0, P4, and CMOS
inverters I0, I1 and I3) that appears only once per chip.  The bypass
detect circuit drives a separate receiver shunt network in each
on-chip TTL receiver via terminal DIFOUT.  Only one receiver and its
shunt network is shown in Fig. 1, but all other TTL receivers are
essentially identical.  In the TTL receiver shown, the shunt network
consists of devices N3 and N11.  All other devices make up one TTL
receiver.

      In the bypass detect portion of Fig. 1, devices P4, N10, N2 and
N0 form a voltage reference to control the transconductance of N1.
P4 and P0 are identical devices to compensate for threshold voltage
shifts attributable to manufacturing variances.  VCC is the off-chip
supply voltage of approximately 5.0 volts.  VDD is the supply voltage
at the output of the on-chip regulator.  ...