In this sixth installment of the series, we will explain the key points to consider when selecting an FPGA power supply from the perspective of FPGA power supply specifications.
Continuing from the previous article, we will look at "Cyclone V (5CSXFC5D)" as an example.
Point 1: Understanding FPGA power specifications
Point 2: Voltage range and accuracy
Point 3: Select a supply current with a margin for the estimated current value.
Point 4: Transient response (transient, PDN listed specifications)
Point 5: Check FPGA startup sequence
Point 6: Waveform at power-on (monotonically increasing)
Point 1: Understand the FPGA power specifications
First, check the required power supply accuracy of the FPGA from the datasheet and pin connection guidelines to correctly understand the power supply specifications required by the FPGA.
Confirmation of FPGA power supply specifications
Check Power Supply Sharing Guide Lines in Pin Connection Guide Lines for voltage and accuracy
Check core (VCC, etc.) voltage and voltage accuracy
Check PLL (VCCA_FPLL, etc.) voltage and voltage accuracy
Check IO voltage and voltage accuracy
Point 2: Voltage range and accuracy
Check the actual voltage range and accuracy of various power supply lines. In the case of the "Cyclone V SX" in this case, the required voltage is 1.1V for VCC, and a range of ±30mV is required.
Check the values in both units.
VCC voltage range is 1.07V to 1.13V, with 1.1V as the center, ±2.72% variation range
VCCA_FPLL voltage range is 2.375V to 2.625V, with 2.5V as the center, ±5% variation range
IO voltage range is 1.71V to 1.89V, with 1.8V as the center, ±5% variation range The range of variation is ±5% when 1.8V is used as the center.
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Point 3: Select a supply current with a margin for the estimated current value.
(*The default value for EPE is +30%.)
Point 4: Transient response (transient, PDN specifications)
In addition to Point 2, another range of transient response is specified for abrupt voltage fluctuations. Since the value differs depending on the device, check the Allowable Ripple of each device in the Introduction sheet of the PDN tool.
(In this case: 5%)
Point 5: Check the FPGA startup sequence
(Refer to the Power-Up Sequence in the device handbook, as each device may have its own boot sequence.
In the case of Cyclone V SX, refer to
Volume 1: Device Interfaces and Integration ⇒ Power Management in Cyclone V Devices in the device handbook.
Point 6: Waveform at power-on (monotonically increasing)
In the case of this example "Cyclone V SX", it is necessary to start up tRamp in the range of [200usec-100msec] minimum.
Cyclone V Device Datasheet
⇒ page 7 Electrical Characatrize
⇒ Operating Conditions
⇒ Recomended Operating Conditions
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In this article, we have explained "Points to Consider When Selecting an FPGA Power Supply" from the FPGA specifications.
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