Circuit for in-system programming of memory device

• US 6,404,174 B1
• Filed: 10/27/2000
• Issued: 06/11/2002
• Est. Priority Date: 10/27/2000
• Status: Expired due to Term

• Current Assignee: ADTRAN Incorporated (ADTRAN Holdings, Inc.)
• Original Assignee: ADTRAN Incorporated (ADTRAN Holdings, Inc.)
• Inventors: Robinson, Steven M., Boudreaux, Ralph R. Jr., McGary, John S.
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/697,900
• Time in Patent Office: 592 Days
• Field of Search: 323/273, 323/275, 323/280, 323/282, 323/285, 323/351
• US Class Current: 323/273
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 16/30 Power supply circuits
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 3/155 using semiconductor devices only

Abstract

A programming circuit is coupled to an input/output pin of a device and is operative to generate a selected one of a plurality of electrical stimuli, such as a programming voltage, high and low logic levels, and a high impedance output, to the device in selected electrical state, without affecting normal device operation. The programming circuit includes a switchmode power converter, a linear regulator, and a control circuit. The programming voltage is generated by the switchmode power converter only when required for programming the device. The linear regulator includes a transistor having its collector-emitter path coupled in circuit with the switchmode converter and an output node, as well as to a voltage divider network. The voltage divider network is coupled to the control input of a precision shunt regulator device, which supplies a base reference for the transistor to establish the value of a voltage to be applied provided from the output node to the device. The base of the linear regulator'"'"'s transistor is also controllably coupled to ground through the collector-emitter path of a steering transistor of the control circuit. The regulator'"'"'s output node is also controllably coupled to ground through the collector-emitter path of a steering transistor of the control circuit. The output node is coupled to a programming (I/O) pin of the device.

Claims

1. A circuit for generating a programming voltage to be applied to an electronic circuit device comprising:

an output node to which said programming voltage is coupled for application to said electronic circuit device;

a switchmode power converter having a clock-controlled switching device coupled in circuit with a supply voltage and an auxiliary energy storage circuit, and having a drive terminal coupled to receive a clock signal, said switchmode power converter being operative, in response to application of said clock signal to said drive terminal, to controllably generate a programming voltage that exceeds a normal operating voltage of said electronic circuit device; and

a voltage regulator, coupled in circuit with said switchmode power converter and said output node, and being operative to regulate said programming voltage for application to said output node and thereby to said electronic circuit device.

2. The circuit according to claim 1, further including a control circuit, coupled with and being controllably operative to control the operation of said switchmode power converter and said voltage regulator, so as to cause a selected one of a plurality of different voltages to be provided at said output node for application to said electronic circuit device, and thereby place said electronic circuit device in a selected one of a plurality electrical states.

3. The circuit according to claim 2, wherein said control circuit is controllably operative to control the operation of said switchmode power converter and said voltage regulator, so as to selectively present a selected one of respective high and low logic level voltages and a high impedance to said output node for application to said electronic circuit device.

4. The circuit according to claim 3, wherein, for the case of presenting said high logic level voltage to said output node, said control circuit is controllably operative to selectively cause said high logic level voltage from said switchmode power converter to be coupled through said voltage regulator to said output node.

5. The circuit according to claim 4, further including an auxiliary voltage coupling circuit, coupled with a high logic level voltage coupling path from said supply voltage to said output node, and being operative to compensate for one or more voltage drops from said supply voltage through said switchmode power converter and said voltage regulator to said output node.

6. The circuit according to claim 4, wherein said voltage regulator is configured to provide different regulator set points for said programming voltage and said high logic level voltage.

7. The circuit according to claim 3, wherein said voltage regulator includes a controlled output circuit, coupled in circuit with said switchmode power converter and said output node and wherein, for the case of presenting said high impedance to said output node, said control circuit is controllably operative to selectively place said controlled output circuit in a high impedance state.

8. The circuit according to claim 2, wherein said control circuit is controllably operative to control the operation of said switchmode power converter and said voltage regulator, so as to cause said output node to selectively provide said programming voltage as generated by said switchmode power converter and regulated by said voltage regulator.

9. The circuit according to claim 3, wherein, for the case of presenting said low logic level voltage to said output node, said control circuit is controllably operative to selectively prevent said high logic level voltage from said switchmode power converter from being coupled through said voltage regulator to said output node.

10. A method of generating a programming voltage for application to an electronic circuit device comprising the steps of:

(a) providing a switchmode power converter having a clock-controlled switching device coupled in circuit with a supply, voltage and an auxiliary energy storage circuit, and having a drive terminal that is adapted to receive a clock signal, said switchmode power converter being operative, in response to application of said clock signal to said drive terminal, to controllably generate a programming voltage that exceeds a normal operating voltage of said electronic circuit device;

(b) coupling a voltage regulator with said switchmode power converter and said output node, said voltage regulator being operative to regulate said programming voltage for application to said output node and thereby to said electronic circuit device; and

(c) applying said clock signal to said drive terminal and thereby causing said switchmode power converter to controllably generate said programming voltage that exceeds said normal operating voltage of said electronic circuit device.

11. The method according to claim 10, further including the step (d) of controlling the operation of said switchmode power converter and said voltage regulator, so as to selectively present a selected one of said programming voltage, respective high and low logic level voltages and a high impedance to said output.

12. The method according to claim 10, wherein said clock signal has a fixed duty cycle.