Cypress Semiconductor NoBL CY7C1472V33 Guia do Utilizador descarregar pdf (Página 23)

ZestSC1 User Guide

CONFIDENTIAL Page 23 of 57

2.5W (500mA @ nominal 5V) is available from USB. The following table shows the typical

quiescent power consumption of the board when connected to a USB host. The remaining

power from the USB 2.5W after allowing for 10% loss in the power supplies is available

for operating power and is also shown in the table below.

FPGA and Memory Quiescent Power (W) Available Operating Power

(W)

400 and 1MB 1.35 1.0

1000 and 1MB 1.40 1.0

1000 and 8MB* 1.80 0.6

To minimise power consumption then the following may be done:

• If the SRAM is not required then drive the SRAM clock high or low.

• Do not use internal pull-ups or pull-downs on the FPGA IO pins.

For extra power there are two power connectors for external power supplies to make the

board self-powered. One is J5, which is a 2.5mm power jack for connection to a mains

power wall adapter. This should be switch mode with low ripple and have an output

voltage between 3.5V and 5.5V (nominally 4.5V or 5.0V), an output current of at least

1A, and a female plug inner diameter of 2.5mm. The plug from the wall adapter

should have +5V power on the outside of the pin and ground on the inside of

the pin. When the plug is inserted in the jack, power from USB is disconnected by the

jack.

There are 3 resettable fuses fitted to the board at the following points:

• 5V power input from all sources

• 5V power output to I/O header

• 3.3V power output to I/O header

All the fuses are resettable 1.5A fuses. If a fuse trips then disconnect power, remove the

fault and wait for the fuse to cool down before reconnecting the power.

Power should be switched off when inserting the mains adapter plug and when changing

the position of J6. This is to avoid current surges and voltage ringing in the mains

adapter wire.

The other power connector is a PC hard disk drive power connector for connecting to a

power cable found inside a PC. J6 is used for selecting either this connector or the power

jack/USB power. J6 should be moved only when all power is off. The PC hard disk

drive power connector is intended for use of the board inside a PC and the board should

be mounted securely using the four corner holes and insulating standoffs in a position

where it cannot touch any other items such as chassis, boards or cables.

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 56 57

Sem comentários

Cypress Semiconductor NoBL CY7C1472V33 Guia do Utilizador Página 23