Putting Altera MAX Series in Hibernation Mode Using User Flash Memory

ID 683668
Date 1/14/2016

1.2. External Hardware Circuitry

An external circuitry is used to control the power supply to the supported Altera device, as well as the input to the counter.

Figure 1. External Hardware CircuitryThe VCCINT/VCCIO power supplies are applicable for MAX II and MAX V devices only. The power supplies for MAX 10 single supply devices are VCC_ONE, VCCA, and VCCIO. The power supplies for MAX 10 dual supply devices are VCC, VCCD_PLL, VCCINT, VCCA, VCCA_ADC, and VCCIO.

A P-channel MOSFET is used to control the power supply to the supported Altera device. If the gate of the P-channel MOSFET is at low-voltage level, the transistor is turned on to allow current to flow through from the power supply to the supported Altera device. If the transistor's gate is at a high-voltage level, the transistor is turned off and the supported Altera device is in powered-down state.

The P-channel MOSFET can be steadily turned off with the 1-kΩ pull-up resistor R1. Besides, I/O pins of the device do not drive out when the device is powered down.

To turn on the P-channel MOSFET, press the pushbutton SW1. Pressing pushbutton SW1 causes the voltage level at the transistor's gate to low and allows the transistor to power up the supported Altera device again.

After power-up, the supported Altera device goes into user mode, at the maximum of 450 µs. The supported Altera device drives the P-channel MOSFET's gate low through its Power-Down-Ready output pin to allow continuous operation even though pushbutton SW1 is released. If the supported Altera device detects that the counter is not active for a pre-defined period of time, the device then drives the ouput pin high. Driving the Power-Down-Ready output pin high turns off the P-channel MOSFET, thus self powering down the supported Altera device.

Pushbutton SW1 is also used for incrementing the count value. The system uses a single pushbutton for powering up the device, as well as incrementing the count value, so you do not need to know whether the device is powered down when you want to increment the count.

As the device recognizes a low pulse as the trigger to increment the count value, resistors R1 and R2 are used as a voltage divider. Even though the device forces the P-channel MOSFET's gate low using the Power-Down-Ready output pin, the node N1 that connects to the Count input pin still has a voltage higher than VIH(min) for the input pin to recognize node N1 as high. It also allows count operation when pushbutton SW1 is pressed, because the voltage level must be lower than VIL(max) to be recognized as low.

Use pushbutton SW2 to reset the counter so that it starts from zero.

Note: The external hardware circuitry described uses the same 3.3-V power supply for VCCINT and VCCIO. Modification to the external hardware circuitry is needed for designs that require VCCIO to be at a different level than VCCINT.
Note: To use the hot-socketing feature when the device is powered down, connect the VCCINT and VCCIO pins to ground.