# Circuits to Implement Power Supply Sequences Using General-Purpose Power Supply ICs　ーSummaryー

2023.04.12

This concludes our discussion of “Circuits to Implement Power Supply Sequences Using General-Purpose Power Supply ICs,” which has extended over 11 articles. In this section we have presented two circuit examples that employ general-purpose power supply ICs to constitute three-output power supply circuits provided with sequencing functions. In order to provide a power supply circuit with sequencing functions, a number of methods can be used, including opting for power supply ICs that have sequence functions or using sequencer ICs. Here, we have achieved sequence functions by combining power supply ICs having enable functions with power-good ICs and comparator ICs. In actual design, the optimum method should be chosen taking into comprehensive consideration the details of the control needed, the circuit configuration (complexity, number of components, and so on), the board area, cost, and other factors.

Below are summaries of the key points of the articles, with links to the articles themselves.

Circuits to Implement Power Supply Sequences Using General-Purpose Power Supply ICs　―Introduction―

・For ICs and electronic equipment requiring multiple power supplies, in some cases ordered turn-on and turn-off, or sequence control, is needed.

・In these articles, examples are presented in which general-purpose power supplies and external circuits are used to implement sequence control, without using sequence control ICs or power supply ICs with sequence support functions.

Power Supply Sequence Specification ①: Power Supply Sequence Specifications and Control Block Diagrams

・In sequence ①, power supplies with three supply voltages are turned on in order, and are shut off in the reverse order.

・For design purposes, the function blocks needed to obtain the target operations are considered.

・To achieve sequence ①, three DCDC ICs, four Power Good circuits, and three discharge circuits are used.

Power Supply Sequence Specification ①: Sequence Operation at Power Turn-on

・In Sequence ①, power supplies with three supply voltages are turned on in order, and are shut off in the reverse order.

・In order to aid understanding of the sequence operation, the operations for turn-on of the three power supply systems were presented separately.

Power Supply Sequence Specification ①: Sequence Operation at Power Shutoff

・In sequence ①, power supplies with three supply voltages are turned on in order, and shut off in the reverse order.

・In order to facilitate understanding of sequence operations, the operations at power shutoff for each of the three power supply systems were illustrated in terms of three stages.

Power Supply Sequence Specification①： Example of Actual Circuit and Component Value Calculations

・A circuit to realize the power supply sequence ① consists of 3 DCDC ICs, 4 Power Good circuits, 3 discharge circuits, and diodes.

Power Supply Sequence Specification①: Example of Actual Operations

・Confirm the specifications, circuit operations, and waveforms for power supply sequence ①.

Power Supply Sequence Specification②: Power Supply Sequence Specifications and Control Block Diagrams

・The specifications of the power supply sequence ② are confirmed.

・A function block diagram to represent the specifications is created.

Power Supply Sequence Specification②: Sequence Operation at Power Turn-on

・In sequence ②, three power supply systems are turned on in order, and are shut off in the same order.

・In order to aid understanding of sequence operation, the operation at the time of turn-on of each of the three power supply systems is shown separately.

Power Supply Sequence Specification②: Sequence Operation at Power Shutoff

・In sequence ②, three power supply systems are turned on in order, and are shut off in the same order.

・In order to aid understanding of sequence operation, the operation at the time of shutoff of each of the three power supply systems is shown separately.

Power Supply Sequence Specification②: Example of Actual Circuit and Component Value Calculations

・A circuit to realize the power supply sequence ② consists of 3 DCDC ICs, 2 Power Good circuits, and 3 discharge circuits.

Power Supply Sequence Specification②: Example of Actual Operations

・The power supply sequence ② specifications, circuit operation, and waveforms are confirmed