Subscriber line interface circuit with intra-operational state selectable supply
View Patent ↗A method of generating a plurality of supply voltages for a plurality of subscriber line channels includes generating a first target VBAT value for a first associated linefeed driver from a first VBAT control. A second target VBAT value for a second associated linefeed driver is generated from a second VBAT control. A selected target VBAT value is generated based upon the first and second target VBAT values. A magnitude of the selected target VBAT value is not less than any maximum of a magnitude of the first and second target VBAT values. A switching regulator is controlled to provide a first generated VBAT corresponding to the selected target VBAT value, wherein the switching regulator provides a second generated VBAT having a pre-determined proportional relationship (p) to the first generated VBAT.
1. A method of generating a plurality of supply voltages for a plurality of subscriber line channels, comprising:
a) generating a first target VBAT value for a first associated linefeed driver from a first VBAT control;
b) generating a second target VBAT value for a second associated linefeed driver from a second VBAT control;
c) generating a selected target VBAT value based at least in part on the first and second target VBAT values, wherein a magnitude of the selected target VBAT value is not less than any maximum of a magnitude of the first and second target VBAT values; and
d) controlling a switching regulator to provide a first generated VBAT corresponding to the selected target VBAT value, wherein the switching regulator provides a second generated VBAT having a pre-determined proportional relationship (p) to the first generated VBAT.
2. The method of claim 1 wherein the switching regulator comprises a transformer having a primary winding and a plurality of secondary windings including an N1 turn secondary winding providing the first generated VBAT and an N2 turn secondary winding providing the second generated VBAT, wherein the pre-determined proportional relationship p=second generated VBAT/first generated
VBAT
=
N
1
N
2
.
3. The method of claim 1 wherein the first and second VBAT controls are implemented within an integrated circuit signal processor.
4. The method of claim 1 wherein the first generated VBAT supplies a first linear regulator having an output node coupled to the first associated linefeed driver, wherein the output node is diode-coupled to receive the second generated VBAT.
5. The method of claim 1 wherein the selected target VBAT value is a selected one of the first and second target VBAT values having a greatest magnitude.
6. The method of claim 1 wherein p≦½.
7. The method of claim 6 wherein p≦⅓.
8. A method of generating a plurality of supply voltages for a plurality of subscriber line linefeed drivers, comprising:
a) generating a first target VBAT value for a first associated linefeed driver from a first VBAT control;
b) generating a second target VBAT value for a second associated linefeed driver from a second VBAT control;
c) generating a selected target VBAT value from the first and second target VBAT values, wherein a magnitude of the selected target VBAT value is not less than any maximum of a magnitude of the first and second target VBAT values if the first and second linefeed drivers have a same operational state, wherein the selected target VBAT value is
1
p
times the one of the first and second target VBAT values having the lowest magnitude if the first and second linefeed drivers have different operational states, wherein p<1; and
d) controlling a switching regulator to provide a first generated VBAT corresponding to the selected target VBAT value, wherein the switching regulator provides a second generated VBAT having a pre-determined proportional relationship (p) to the first generated VBAT.
9. The method of claim 8 wherein the switching regulator comprises a transformer having a primary winding and a plurality of secondary windings including an N1 turn secondary winding providing the first generated VBAT and an N2 turn secondary winding providing the second generated VBAT, wherein the pre-determined proportional relationship p=second generated VBAT/first generated
VBAT
=
N
1
N
2
.
10. The method of claim 8 wherein the first and second VBAT controls are implemented within an integrated circuit signal processor.
11. The method of claim 8 wherein the first generated VBAT supplies a first linear regulator having an output node coupled to the first associated linefeed driver, wherein the output node is diode-coupled to receive the second generated VBAT.
12. The method of claim 8 wherein the linefeed drivers have a same operational state, wherein the selected target VBAT value is a selected one of the first and second target VBAT values having a greatest magnitude.
13. An apparatus for providing a plurality of supply levels to a plurality of subscriber line linefeed drivers, comprising:
a switching regulator providing a first generated VBAT corresponding to a selected target VBAT value, wherein the switching regulator provides a second generated VBAT having a pre-determined proportional relationship (p) to the first generated VBAT;
a linear regulator receiving the first generated VBAT, wherein an output of the linear regulator is coupled to a node supplying a first linefeed driver; and
a diode coupling the node to the second generated VBAT;
wherein the switching regulator comprises a transformer having a primary winding and a plurality of secondary windings including an N1 turn secondary winding providing the first generated VBAT and an N2 turn secondary winding providing the second generated VBAT, wherein the pre-determined proportional relationship p=second generated VBAT/first generated
VBAT
=
N
1
N
2
.