W27E020 Datasheet, PDF (3/14 Pages) Winbond – 256K X 8 ELECTRICALLY ERASABLE EPROM

Preliminary W27E020
Standby Mode
The standby mode significantly reduces VCC current. This mode is entered when CE = VIH. In
standby mode, all outputs are in a high impedance state, independent of OE and PGM.
Two-line Output Control
Since EPROMs are often used in large memory arrays, the W27E020 provides two control inputs for
multiple memory connections. Two-line control provides for lowest possible memory power
dissipation and ensures that data bus contention will not occur.
System Considerations
EPROM power switching characteristics require careful device decoupling. System designers are
concerned with three supply current issues: standby current levels (ISB), active current levels (ICC),
and transient current peaks produced by the falling and rising edges of CE. Transient current
magnitudes depend on the device output's capacitive and inductive loading. Two-line control and
proper decoupling capacitor selection will suppress transient voltage peaks. Each device should have
a 0.1 µF ceramic capacitor connected between its VCC and GND. This high frequency, low inherent-
inductance capacitor should be placed as close as possible to the device. Additionally, for every eight
devices, a 4.7 µF electrolytic capacitor should be placed at the array's power supply connection
between VCC and GND. The bulk capacitor will overcome voltage slumps caused by PC board trace
inductances.
TABLE OF OPERATING MODES
VPP = 12V, VPE = 14V, VHH = 12V, VCP = 5V, VCE = 5V, VID = 14V, X = VIH or VIL
MODE
PINS
Read
Output Disable
Standby (TTL)
Standby (CMOS)
Program
Program Verify
Program Inhibit
Erase
Erase Verify
Erase Inhibit
Product Identifier-
manufacturer
CE
OE PGM ^{A0 A9 VCC VPP OUTPUTS}
VIL
VIL
X
X
X VCC VCC DOUT
VIL
VIH
X
X
X VCC VCC High Z
VIH
X
X
X
X VCC VCC High Z
VCC ±0.3V X
X
X
X VCC VCC High Z
VIL
VIH VIL
X
X VCP VPP DIN
VIL
VIL VIH
X
X VCC VPP DOUT
VIH
X
X
X
X VCP VPP High Z
VIL
VIH VIL VIL VID VCE VPE FF (Hex)
VIL
VIL VIH
X
X VCC VPE DOUT
VIH
X
X
X
X VCE VPE High Z
VIL
VIL
X
VIL VHH VCC VCC DA (Hex)
Product Identifier-device
VIL
VIL
X
VIH VHH VCC VCC 85 (Hex)
Publication Release Date: December 1997
-3-
Revision A1