EP0137933A2
Expired / Lapsed
EP
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Signal line precharging tristate drive circuit
Assignee: International Business Machines Corp
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Filing: 1984-08-01
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Granted: —
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Expires: 2004-08-01
Abstract
Abstract The signal line precharging tristate driver circuit quickly and automatically precharges its off-chip signal line to the desired level just before it switches to its tristate or high impedance output condition. This is accomplished by providing precharge circuitry (10) coupled to the driver circuit (4 through 9) and responsive to the tristate control signal for overriding the normal input data signal and causing the driver circuit to commence charging the signal line. There is further provided tristate circuitry (20, 30, 31, 34, 35, 37, 38, 39) coupled to the driver circuit and responsive to its output voltage level for switching the driver circuit to the high impedance output condition when its output voltage and, hence, the signal line voltage reaches a desired predetermined value.
Inventors
- 👤 Wayne Richard Kraft
- 👤 Victor Stewart Moore
- 👤 William Leonard Stahl, Jr.
- 👤 Nandor Gyorgy Thoma
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 12:49
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/01; H03K5/02; H03K5/023; H03K19/00; H03K19/02; H03K19/08; H03K19/094; H03K19/09425; H03K19/09429
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
158 words
A signal line precharging tristate driver circuit formed on an integrated circuit chip for driving a signal line located off the chip including driver circuitry (4 through 9) responsive to an input signal for producing on the signal line an output signal having a value determined by the value of the input signal and tristate circuitry (20, 30, 31, 34, 35, 37, 38, 39) coupled to the driver circuitry and responsive to a control signal for forcing the driver circuitry in a high impedance output condition characterized in that it comprises a precharge circuitry (10) coupled to the driver circuitry and responsive to the control signal for overriding the input signal and causing the driver circuitry to commence charging the signal line and in that the tristate circuitry is responsive to the output voltage level of the driver circuitry for switching the driver circuitry to a high impedance output condition when said output voltage reaches a predetermined level.
Claim 2
Dependent Claim
158 words
A signal line precharging tristate driver circuit formed on an integrated circuit chip for driving a signal line located off the chip including driver circuitry (4 through 9) responsive to an input signal for producing on the signal line an output signal having a value determined by the value of the input signal and tristate circuitry (20, 30, 31, 34, 35, 37, 38, 39) coupled to the driver circuitry and responsive to a control signal for forcing the driver circuitry in a high impedance output condition characterized in that it comprises a precharge circuitry (10) coupled to the driver circuitry and responsive to the control signal for overriding the input signal and causing the driver circuitry to commence charging the signal line and in that the tristate circuitry is responsive to the output voltage level of the driver circuitry for switching the driver circuitry to a high impedance output condition when said output voltage reaches a predetermined level.
Claim 3
Dependent Claim
19 words
A circuit in accordance with claim 1 wherein the driver circuitry (4 through 9) is a push-pull driver circuit.
Claim 4
Dependent Claim
29 words
A circuit in accordance with any preceding claim wherein the input signal is a binary data signal and the output signal is a replica of the binary data signal.
Claim 5
Dependent Claim
44 words
A circuit in accordance with any preceding claim wherein the precharge circuitry (10) is coupled to the input portion (4) of the driver circuitry (4 through 9) and responsive to the control signal for forcing the driver circuitry to produce a high level output.
Claim 6
Dependent Claim
84 words
A circuit in accordance with any preceding claim wherein the tristate circuitry (20, 30, 31, 34, 35, 37, 38, 39) includes voltage sensitive circuitry (20, 34, 35, 37) coupled to the output of the driver circuitry (4 through 9) for forcing the driver circuitry to its high impedance output condition when its output voltage reaches the predetermined level and circuitry (30, 31) responsive to the absence of the control signal for disabling the voltage sensitive circuitry during the normal operation of the driver circuitry.
Claim 7
Dependent Claim
98 words
A circuit in accordance with any preceding claim wherein the tristate circuitry (20, 34, 35, 37) includes a bistable circuit (20) which is maintained in a first state when the control signal is absent and which is operative when the control signal is present to switch to a second state when the output voltage of the driver circuit (4 through 9) reaches the predetermined level and circuitry (37) coupled to the driver circuitry and to the bistable circuit for maintaining the high impedance output condition of the driver circuitry when the bistable circuit is in its second state.
Claim 8
Dependent Claim
60 words
A circuit in accordance with any preceding claim including fast-acting circuitry (38, 39) responsive to the control signal and to the output voltage of the driver circuitry (4 through 9) for rapidly initiating the switching of the driver circuitry to its high impedance output condition when the control signal is present and when said output voltage reaches the predetermined level.
References Cited (Backward Citations)
No citation records indexed.
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