Method and apparatus for rapidly and dynamically adjusting current limiting in a portable communication device

• US 10,468,872 B1
• Filed: 02/28/2019
• Issued: 11/05/2019
• Est. Priority Date: 07/30/2018
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Bartels, Peter J., Alfaro, Javier, Garcia, Hugo, Alonso, Kevin, Glass, Stephen C.
• Primary Examiner(s): Vuong, Quochien B
• Application Number:
  US16/289,207
• Time in Patent Office: 250 Days
• Field of Search: 455 902, 4555561, 455557, 455574
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: H02H 1/0007 concerning the detecting means in general G01R or other subclasses of G01; reed switches H01H71/2445
• CPC Class Codes: H02H 9/02 responsive to excess current current limitation for voltage regulators G05F1/573; disconnection after limiting H02H3/025
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/183 with semiconductor devices only
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/3833 Hand-held transceivers
• CPC Class Codes: H04B 1/401 for selecting or indicating operating mode

Abstract

A battery operated portable communication device provides converged functionality while avoiding resets to the device. Composite logic circuitry formed of at least one comparator and a logic interface controls current limiting to a primary load formed of high power land mobile radio (LMR) devices and programming to secondary loads formed of non-LMR peripherals. At least one current limit control signal is used to control current to the primary load under high current mode operations. Another control signal provides an interruption alert to a slave processor for controlled programming of the secondary loads during the high current operations of the primary load. Current to the primary load is restored while the secondary load is interrupted. Operation of secondary load processes is resumed when the primary load ceases high power operation.

Claims

1. A portable communication device, comprising:

a battery;

a push-to-talk (PTT) button for asserting a transmit event signal;

a master processor for controlling current limiting of primary loads of the portable communication device;

a slave processor for controlling secondary loads;

a finite state machine (FSM) defining a plurality of current limit operating states for the portable communication device based on a battery profile of the battery;

a comparator programmed by the master processor with a reference voltage based on the battery profile, the comparator comparing the reference voltage to a current sense output voltage sensed at the slave processor and the secondary loads, the comparator generating a comparator output signal for input to the finite state machine; and

wherein

the finite state machine (FSM) receives the comparator output signal and the transmit event signal and determines a discrete operating state of the plurality of current limit operating states, the FSM generating a plurality of current limit control signals in response thereto for controlling the primary and secondary loads in accordance with the determined discrete operating state.

2. The portable communication device of claim 1, wherein the plurality of current limit operating states comprise at least:

a normal operating state without current limiting;

a moderate current limit operating state; and

a maximum current limit operating state.

3. The portable communication device of claim 2, wherein in the normal operating state the portable communication device operates as a converged device providing both land mobile radio (LMR) functionality along with non-LMR processes, the non-LMR processes being controlled by the slave processor.

4. The portable communication device of claim 3, wherein the maximum current limit operating state and the moderate current limit operating state control current limiting of the LMR functionality and non-LMR processes in response to a transmit event, which would otherwise result in an over current condition.

5. The portable communication device of claim 3, wherein the LMR functionality is provided by a Tx RFPA and a transmit audio PA, and wherein the maximum current limiting state is configured to:

assert a transmit radio frequency power amplifier (Tx RFPA) current limit;

assert a transmit audio power amplifier (Tx Audio PA) current limit; and

assert a slave processor interrupt.

6. The portable communication device of claim 5, wherein the moderate current limiting state is configured to:

deassert the Tx RFPA current limit;

keep the Tx audio PA current limited; and

keep the slave processor interrupt asserted.

7. The method of claim 6, wherein the normal operating state is configured to:

keep the Tx RFPA current limit deasserted;

deassert the Tx audio PA current limiting; and

deassert the slave processor interrupt.

8. A portable communication device, comprising:

a battery having a battery profile;

a master processor for controlling primary loads;

a slave processor for controlling secondary loads, and wherein primary load operations and secondary load processes operate in parallel during a normal mode state;

a current sensor for sensing current of the slave processor and slave processor secondary loads;

a comparator coupled to the master processor, the comparator being programmed with a voltage threshold based on the battery profile, the comparator comparing the voltage threshold to a current sense voltage of the slave processor and slave processor secondary loads; and

a finite state machine (FSM) coupled to the comparator, the finite state machine (FSM) receiving the comparator output signal and a transmit event signal and determining a discrete operating state of the plurality of operating states, the FSM generating a plurality of current limit control signals in response thereto for controlling the primary and secondary loads in accordance with the determined discrete operating state.

9. The portable communication device of claim 8, further comprising:

a preprogrammed delay timer for maintaining an enabled current limit state for a predetermined delay time.

10. The portable communication device of claim 8, wherein the primary load comprises at least:

a land mobile radio (LMR) radio frequency power amplifier (RFPA); and

an audio PA.

11. The portable communication device of claim 10, wherein the secondary load comprises at least one of:

a long term evolutions (LTE) feature;

a WiFi feature; and

a GPS feature.

12. The portable communication device of claim 8, wherein a maximum current limit state is initiated in response to a PTT assertion, and the maximum current limit state remains enabled until the comparator trips indicating that the slave processor and secondary loads have decreased current draw, as sensed at the current sensor, enough to allow for full power primary load operation.

13. The portable communication device of claim 12, wherein the finite state machine transitions from the maximum current limiting state to a moderate current limiting state in response to an output of the comparator output tripping, and a preprogrammed delay timer expiring.

14. The portable communication device of claim 13, wherein the finite state machine transitions from the moderate current limiting state back to the maximum current limiting in response to the comparator output tripping again indicating an increase in current draw.

15. The portable communication device of claim 8, wherein the state machine only transitions back to a normal operating state once the transmit event has concluded.

16. The portable communication device of claim 8, wherein the current limit control signals control a switched resistive network for current limiting the primary loads.

17. The portable communication device of claim 8, wherein the current limit control signals control a digital signal processor (DSP) for current limiting the primary loads.