Wide input voltage range power supply circuit
A wide input voltage power supply circuit for a load includes a first stage and a second stage. The first stage includes a linear regulator circuit configured to maintain an output voltage at a predetermined output voltage level. The linear regulator includes an input for shutting the linear regulator off when an input voltage exceeds a predetermined shut off threshold. The second stage includes a high voltage detection circuit coupled to the input of the linear regulator. The high voltage detection circuit is configured to detect the level of the input voltage and to shut the linear regulator off when the input voltage exceeds the predetermined shut off threshold. An under voltage lockout circuit may be included, the under voltage lockout circuit configured to set a minimum turn-on voltage for the load.
1. A wide input voltage power supply circuit for a load, the circuit comprising:
a first stage comprising a linear regulator circuit configured to maintain an output voltage at a predetermined output voltage level, the linear regulator circuit including an input for shutting the linear regulator off when an input voltage exceeds a predetermined shut off threshold;
a second stage comprising a high voltage detection circuit coupled to the input of the linear regulator circuit, the high voltage detection circuit configured to detect the level of the input voltage and to shut the linear regulator circuit off when the input voltage exceeds the predetermined shut off threshold;
a capacitor snubber circuit coupled to an input of the high voltage detection circuit, the capacitor snubber circuit to divert current from a line inductance when the high voltage detection circuit turns the linear regulator circuit off, and
an under voltage lockout circuit coupled to the power supply circuit, the under voltage lockout circuit configured to set a minimum turn-on voltage for the load and prevent operation of the load until the minimum turn-on voltage is reached.
2. The circuit according to claim 1 ,
wherein the predetermined output voltage level is between 16VDC and 26VDC.
3. The circuit according to claim 1 ,
wherein the predetermined shut off threshold is between 100VDC and 140VDC.
4. The circuit according to claim 1 ,
wherein the linear regulator circuit comprises a FET coupled to a zener diode.
5. The circuit according to claim 1 ,
wherein the DC input voltage range is between 16VDC to 120VDC.
6. The circuit according to claim 1 ,
wherein the AC input voltage range is between 19VAC to 264VAC.
7. The circuit according to claim 1 ,
wherein the load comprises a 24V relay.
8. The circuit according to claim 1 ,
wherein a DC input voltage range ratio is about 1:8.
9. The circuit according to claim 1 ,
wherein an AC input voltage range ratio is about 1:14.
10. A relay assembly comprising:
a relay including a relay coil;
a first stage comprising a linear regulator circuit configured to maintain an input voltage at a predetermined output voltage level between 16VDC and 26VDC, the linear regulator circuit including an input for shutting the linear regulator circuit off when the input voltage exceeds a predetermined shut off threshold of between 100VDC and 140VDC;
a second stage comprising a high voltage detection circuit coupled to the input of the linear regulator circuit, the high voltage detection circuit configured to detect the level of the input voltage and to shut the linear regulator off when the input voltage exceeds the predetermined shut off threshold;
a capacitor snubber circuit coupled to an input of the high voltage detection circuit, the capacitor snubber circuit to divert current from a line inductance when the high voltage detection circuit turns the linear regulator off;
an under voltage lockout circuit coupled to the power supply circuit, the under voltage lockout circuit configured to set a minimum turn-on voltage for the load and prevent operation of the load until the minimum turn-on voltage is reached; and
an LED configured to indicate the conductive state of the relay coil.
11. The relay assembly according to claim 10 ,
wherein the linear regulator circuit comprises a FET coupled to a zener diode.
12. A circuit for a load, the circuit comprising:
a rectifier circuit configured to rectify an AC input line cycle;
a linear regulator configured to shut off during a first portion of the rectified AC input line cycle and to regulate a second portion of the rectified AC input line cycle;
a high voltage detection circuit coupled to the linear regulator, the high voltage detection circuit configured to detect a level of the rectified AC input line cycle and to shut the linear regulator off when the rectified AC input line cycle exceeds a predetermined shut off threshold;
a capacitor snubber circuit coupled between the rectifier circuit and the high voltage detection circuit, the capacitor snubber circuit to divert current from a line inductance when the high voltage detection circuit turns the linear regulator off; and
an under voltage lockout circuit coupled to the power supply circuit, the under voltage lockout circuit configured to set a minimum turn-on voltage for the load and prevent operation of the load until the minimum turn-on voltage is reached.
13. The circuit according to claim 12 ,
further including an LED configured to indicate the conductive state of the load.
14. The circuit according to claim 12 ,
further including a relay, the relay including a relay coil.
15. The circuit according to claim 12 ,
further comprising a signal conditioning circuit configured to regulate the AC input line cycle.
16. The circuit according to claim 12 ,
wherein the linear regulator comprises a FET coupled to a zener diode.