Cmod A7 Reference Manual

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Page 3 of 10

Net

name

Upstream

net name

Power IC

Type

Power

IC

Label

Min/Typ/Max

Voltage

Max.

Current

Major Devices

and Connectors

VCC1V0

VU

Switching

PS

IC10

0.95V/1.00V/1.05V

1.2A

FPGA Core and

Block RAM

VCC1V8

VU

Switching

PS

IC10

1.71V/1.80V/1.89V

0.6A

FPGA AUX

and ADC, USB

Core

VCC3V3

VU

Switching

PS

IC10

3.135V/3.30V/3.465V

0.6A

SRAM, USB

Controller,

PMOD, LEDS,

Buttons, FPGA

USER I/O

Table 1.1. Power Rail Characteristics.

1.1

Power Input Options

It is possible to power the Cmod A7 from either USB or from an external power supply attached to pins 24 and 25

of the DIP connector, labeled “VU” and “GND”, respectively. The required characteristics of a power source

attached to either of these two options is outlined in Table 1.1.1.

Connector Type

Connector Label

Schematic net name

Min/Rec/Max Voltage

USB

J3

USB5V0

4.5/5/5.5

DIP

J1 (Pin 24)

VU

3.32/5/5.5

Table 1.1.1. Power source options.

The minimum external voltage that can be applied to VU depends on the amount of current drawn from the

VCC3V3 rail via the Pmod header. With 0mA drawn from the Pmod header, the minimum external voltage is 3.32V.

With 100mA drawn from the Pmod header, the minimum external voltage is 3.38V. With 250mA drawn from the

Pmod header, the minimum external voltage is 3.48V.

When the Cmod A7 is being powered by the USB connector, the voltage from the USB device is driven onto the VU

pin. This allows users to power an external circuit from the USB host in addition to the Cmod A7. The VU pin is

driven via a schottky diode, so a small voltage drop will occur, but it should be assumed the voltage present on VU

will be close to 5V.

Warning: When a USB host is attached to the Micro-USB connector, the VU pin on the DIP connector (pin 24) is

driven to the voltage being provided by the USB host (typically between 4.5V-5.5V). If you have a power source

attached to the VU pin, you must disconnect it before attaching a USB host, or risk damaging it. This can be

particularly dangerous if the power source is a battery.