Circuit for detecting a level or a variation of an input direct voltage

• US 5,864,219 A
• Filed: 02/28/1997
• Issued: 01/26/1999
• Est. Priority Date: 03/01/1996
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Fink, Helmut
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US08/808,593
• Time in Patent Office: 697 Days
• Field of Search: 302/125, 302/132, 302/134, 302/136, 302/139, 302/163, 302/147, 302/138, 302/DIG. 21, 302/155
• US Class Current: 320/132
• CPC Class Codes: G01R 19/16576 comparing DC or AC voltage with one threshold G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient
• CPC Class Codes: H03M 1/504 using pulse width modulation

Abstract

A circuit for detecting a level of an input direct voltage comprises a comparator for comparing the input direct voltage with a reference signal, which by means of an integrator is derived from pulses whose charge quantity is variable in dependence on a comparator direct voltage. The reference voltage has a d.c. component and an a.c. component. The comparator supplies comparator pulses of a given pulse duration when the d.c. component of the reference voltage is substantially equal to the input direct voltage. The level of the input direct voltage is determined from the charge quantity of the pulses and from the pulse duration of the comparator pulses.

Claims

1. A circuit for detecting a level or a level variation of an input direct voltage, comprising:

an input terminal, to which the input direct voltage can be applied,

a comparator having a first input, a second input and an output, which first input is connected to the input terminal, which second input is arranged to receive a reference signal, and on which output a comparator signal is available,

a control information generation device by means of which control information corresponding to the comparator signal of the comparator can be generated,

a controllable pulse generator for generating pulses having charge quantities, which pulses are available on an output of the pulse generator and which are variable with respect to their charge quantity by means of said control information which is applied to the pulse generator, and,

an integrator having an input connected to the output of the pulse generator and having an output connected to the second input of the comparator and provided to form the reference signal, the reference signal having a d.c. component corresponding to the instantaneous charge quantity of the pulses of the pulse generator, and having an a.c. component superposed on the d.c. component;

characterized in that

the integrator is adapted to form a reference signal in which the frequency of the a.c. component corresponds to the frequency of the pulses of the pulse generator,

the comparator has its output connected to a detection device by means of which the presence of a comparator direct voltage and the presence of comparator pulses can be detected and by means of which the control information generation device can be controlled in such a manner that, upon a detection of the presence of a comparator direct voltage, the control information for the pulse generator can be generated, and, after a detection of the occurrence of comparator pulses, the generation of control information for the pulse generator can be terminated, and,

the comparator further has its output connected to a time measuring device by means of which, after termination of the generation of the control information for the pulse generator, time information about the duration of the comparator pulses or the comparator pulse spacings can be derived, and,

the circuit further comprises a logic device which detects a level or a level variation of the input direct voltage in dependence upon the charge quantity of the pulses of the pulse generator, and said time information.

2. A circuit as claimed in claim 1, characterized in that the integrator is adapted to form a reference signal whose a.c. component is a sawtooth signal superposed on the d.c. component of the reference signal.

3. A circuit as claimed in claim 1, characterized in that the detection device and the time measuring device are implemented by means of a single counting device.

4. A circuit as claimed in claim 1, characterized in that the detection device and the control information generation device and the pulse generator and the time measuring device and the logic device are implemented by means of a microcomputer.

5. A circuit as claimed in claim 1, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

6. A circuit as claimed in claim 5, characterized in that in the circuit arrangement for charging it serves to detect a decrease in level of the charging voltage.

7. A circuit as claimed in claim 2, characterized in that the detection device and the time measuring device are implemented by means of a single counting device.

8. A circuit as claimed in claim 2, characterized in that the detection device and the control information generation device and the pulse generator and the time measuring device and the logic device are implemented by means of a microcomputer.

9. A circuit as claimed in claim 3, characterized in that the detection device and the control information generation device and the pulse generator and the time measuring device and the logic device are implemented by means of a microcomputer.

10. A circuit as claimed in claim 7, characterized in that the detection device and the control information generation device and the pulse generator and the time measuring device and the logic device are implemented by means of a microcomputer.

11. A circuit as claimed in claim 2, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

12. A circuit as claimed in claim 3, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

13. A circuit as claimed in claim 4, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

14. A circuit as claimed in claim 7, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

15. A circuit as claimed in claim 8, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

16. A circuit as claimed in claim 9, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

17. A circuit as claimed in claim 10, characterized in that the circuit forms part of a circuit arrangement for charging at least one rechargeable battery and in this circuit arrangement serves to detect a level or a level variation of the charging voltage appearing across the battery during a charging process.

18. A circuit as claimed in claim 4, characterized in that in the circuit arrangement for charging it serves to detect a decrease in level of the charging voltage.

19. A circuit as claimed in claim 11, characterized in that in the circuit arrangement for charging it serves to detect a decrease in level of the charging voltage.

20. A circuit as claimed in claim 17, characterized in that in the circuit arrangement for charging it serves to detect a decrease in level of the charging voltage.