Rainbow Electronics br9080af-w - Manual (Page 10)

BR9080AF-W / BR9080ARFV-W / BR9080ARFVM-W /
Memory ICs BR9016AF-W / BR9016ARFV-W / BR9016ARFVM-W
10/12
!
! ! ! Operation notes
(1) Turning the power supply on and off
1) When the power supply is turned on and off, CS should be set to HIGH (=V
CC
).
2) When CS is LOW, the command input reception state (active) is entered. If the power supply is turned on in this state,
erroneous operations and erroneous writing can occur because of noise and other factors. To avoid this, make sure
CS is set to HIGH (=V
CC
) before turning on the power supply.
(Good example) Here, the CS pin is pulled up to V
CC
.
When turning off the power supply, wait at least 10msec before turning it on again. Failing to
observe this condition can result in the internal circuit failing to be reset when the power supply is
turned on.
(Bad example) CS is LOW when the power supply is turned on or off.
In this case, because CS remains LOW, the EEPROM may perform erroneous operations or
write erroneous data because of noise or other factors.
* Please be aware that the case shown in this example can also occur if CS input is HIGH-Z.
V CC
V CC
GND
V CC
GND
CS
Good example Bad example
Fig.9
(2) Noise countermeasures
1) SK noise
If noise occurs at the rise of the SK clock input, the clock is assumed to be excessive, and this can cause malfunction
because the bits are out of alignment.
2) WC noise
During a writing operation, noise at the WC pin can be erroneously judged to be data, and this can cause writing to be
forcibly interrupted.
3) V
CC
noise
Noise and surges on the power supply line can cause malfunction. We recommend installing a bypass capacitor
between the power supply and ground to eliminate this problem.