BR93L86F-WE2 Rohm Semiconductor, BR93L86F-WE2 Datasheet - Page 36

• Manufacturer Part Number: BR93L86F-WE2
• Description: IC EEPROM 16KBIT 2MHZ 8SOP
• Manufacturer: Rohm Semiconductor

Specifications of BR93L86F-WE2

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 16K (1K x 16)
• Speed: 2MHz
• Interface: Microwire, 3-Wire Serial
• Voltage - Supply: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-SOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: BR93L86F-WE2TR

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BR93L□□-W Series, 93A□□-WM Series, BR93H□□-WC Series
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6) Notes on power ON/OFF
7) Noise countermeasures
・At power ON/OFF, set CS “L”.
○POR citcuit
○LVCC circuit
○VCC noise (bypass capacitor)
○SK noise
When CS is “H”, this IC gets in input accept status (active). At power ON, set CS “L” to prevent malfunction from noise.
(When CS is in “L” status, all inputs are cancelled.) At power decline low power status may prevail. Therefore, at power
OFF, set CS “L” to prevent malfunction from noise.
This IC has a POR (Power On Reset) circuit as a mistake write countermeasure. After POR action, it gets in write
disable status. The POR circuit is valid only when power is ON, and does not work when power is OFF. However, if CS is
“H” at power ON/OFF, it may become write enable status owing to noises and the likes. For secure actions, observe the
follwing conditions.
1. Set CS=”L”
2. Turn on power so as to satisfy the recommended conditions of tR, tOFF, Vbot for POR circuit action.
LVCC (VCC-Lockout) circuit prevents data rewrite action at low power, and prevents wrong write.
At LVCC voltage (Typ.=1.9V) or below, it prevent data rewrite.
When noise or surge gets in the power source line, malfunction may occur, therefore, for removing these, it is
recommended to attach a by pass capacitor (0.1μF) between IC VCC and GND, At that moment, attach it as close to IC
as possible.And, it is also recommended to attach a bypass capacitor between board VCC and GND.
When the rise time (tR) of SK is long, and a certain degree or more of noise exists, malfunction may occur owing to clock
bit displacement.
To avoid this, a Schmitt trigger circuit is built in SK input. The hysteresis width of this circuit is set about 0.2V, if noises
exist at SK input, set the noise amplitude 0.2Vp-p or below. And it is recommended to set the rise time (tR) of SK 100ns
or below. In the case when the rise time is 100ns or higher, take sufficient noise countermeasures. Make the clock rise,
fall time as small as possible.
（Bad example）CS pin is pulled up to Vcc.
In this case, CS becomes “H” (active status), EEPROM may
malfunction or have write error due to noises. This is true even
when CS input is High-Z.
V
CC
0
VCC
CS
VCC
GND
VCC
GND
Fig.52 Timing at power ON/OFF
t
OFF
Bad example
Fig.53 Rise waveform diagram
t
R
Vbot
Good example
36/40
（Good example）It is “L” at power ON/OFF.
When power is turned on without observing this condition,
Set 10ms or higher to recharge at power OFF.
IC internal circuit may not be reset.
Recommended conditions of t
100m s or below 10m s or higher 0.2V or below
10m s or below
t
R
10m s or higher 0.3V or below
t
O FF
R
, t
Technical Note
OFF
2011.02 - Rev.F
, Vbot
V bot