Circuits, devices, methods and systems to secure power-up for battery operating devices even with low current chargers and to execute other performances

1. An electronic circuit comprising:

a powering circuit having an electrical input, a charging output and a voltage output;

a functional electronic circuit coupled to the voltage output and configured to be controlled based on a state of a control signal; and

a safe-start circuit configured to:

when a system voltage at the voltage output drops below a first threshold, deassert the control signal, and cause a crash timer to activate for a first period of time, and

in response to the system voltage increasing above a second threshold during the first period of time, cause the functional electronic circuit to be in a low-power state until detecting a first charging condition based on the charging output.

2. The electronic circuit of claim 1 , wherein the safe-start circuit is configured to:

detect a charger detachment event when the system voltage remains below the second threshold during the first period of time;

in response to detecting the charger detachment event, deassert the control signal; and

after the charger detachment event, and in response to detecting a next charger attachment event, assert the control signal.

3. The electronic circuit of claim 1 , wherein the safe-start circuit is configured to, in response to the system voltage remaining below the second threshold during the first period of time, transition into a circuit state indicative of no-supply.

4. The electronic circuit of claim 1 , further comprising a power management circuit configured to control the functional electronic circuit based on the control signal.

5. The electronic control circuit claimed in of claim 4 , wherein the safe-start circuit is coupled by a control output line to the power management circuit, wherein the control output line is configured to carry the control signal.

6. The electronic circuit of claim 5 , further comprising:

a battery connector;

a first package enclosing the safe-start circuit and the powering circuit; and

a second package enclosing the power management circuit, wherein:

the charging output is coupled to the battery connector, and

the safe-start circuit is coupled to the battery connector.

7. The electronic circuit of claim 1 , wherein the powering circuit is coupled to a USB connector for entry of power from the USB connector via the electrical input into the powering circuit.

8. The electronic circuit of claim 1 , further comprising a battery gauge circuit configured to, in cooperation with the safe-start circuit, control a charging of a battery coupled to the charging output.

9. The electronic circuit of claim 1 , wherein the safe-start circuit comprises a bad-battery detection circuit.

10. The electronic circuit of claim 1 , further comprising a serial data transfer physical layer circuit and a serial data transfer connector coupled to the serial data transfer physical layer circuit, the serial data transfer physical layer circuit coupled to the functional electronic circuit and to the safe-start circuit.

11. The electronic circuit of claim 1 , wherein the low-power state of the functional electronic circuit is a power down state.

12. The electronic circuit of claim 1 , wherein the second threshold is higher than the first threshold.

13. The electronic circuit of claim 1 , wherein detecting the first charging condition comprises detecting a battery voltage at the charging output being higher than a third threshold.

14. The electronic circuit of claim 13 , wherein the third threshold is lower than the second threshold and higher than the first threshold.

15. The electronic circuit of claim 2 , wherein detecting the next charger attachment event comprises detecting the next charger attachment event based on the system voltage.

16. The electronic circuit of claim 1 , wherein the powering circuit comprises:

a DC/DC circuit having an input coupled to the electrical input, and an output coupled to the voltage output; and

a linear charger having an input coupled to the voltage output, and an output coupled to the charging output.

17. The electronic circuit of claim 1 , wherein the safe-start circuit comprises:

a first comparator having a first input coupled to the voltage output, and a second input configured to receive the first threshold; and

a second comparator having a first input coupled to the voltage output, and a second input configured to receive the second threshold.

18. The electronic circuit of claim 17 , wherein the safe-start circuit further comprises a state machine having a first input coupled to an output of the first comparator, a second input coupled to an output of the second comparator, a third input coupled to an output of the crash timer, and an output configured to generate the control signal.

19. The electronic circuit of claim 18 , wherein the safe-start circuit further comprises a third comparator having a first input coupled to the charging output, and an output coupled to the state machine.

20. The electronic circuit of claim 18 , wherein the safe-start circuit further comprises an energy level digital comparator having a first input coupled to the charging output, and an output coupled to the state machine.