–100 µA Maximum Standby
– 50 mA Maximum Active at 5 MHz
• Wide Selec tion of JEDEC Standard Packages
– 40-Lead 600 mil PDIP
– 40-Lead SOIC (SOP)
– 48-Lead TSOP (12 mm x 20 mm)
• 5V ± 10% Power Supply
• High Reliability CMOS Technology
– 2,000V ESD Protection
– 200 mA Latchup Immunity
• Rapid
• CMOS and TTL Compatible Inputs and Outputs
• Integrated Product Identification Code
• Commercial and Industrial Temperature Ranges
™
Programming Algorithm - 50 µs/word (typical)
AT27C400
4-Megabit
(256K x 16 or
512K x 8) OTP
EPROM
Description
The AT27C400 is a low-power, high-performance 4,194,304-bit one-time programmable read only memory (OTP EPROM) organized as either 256K by 16 or 512K by 8
bits. It requires a single 5 V power supply in normal r ead mode oper ation. Any word
can be accessed in less than 70 ns, elimi nating the need for speed-re ducing WAIT
states. The by-16 organization makes this part ideal for high-performance 16- and 32bit microprocessor systems.
The AT27C400 can be organized as either word-wide or
byte-wide. The organization is selected v ia the BYTE
pin. When BYTE/VPP is asserted high (VIH), the word-wide
organization is s elected and the O15/A-1 p in is use d for
O15 data output. When BYTE
byte-wide organization is selected and the O15/A-1 pi n is
used for the address pin A-1. When the AT27C400 is logically regarded as x1 6 (word-wide ), but read in the by tewide mode, then with A-1 = V
word are s el ec ted a nd wi th A- 1 = V
16-bit word are selected.
In read mode, the AT27C400 typically consumes 15 mA.
Standby mode supply current is typically less than 10
The AT27C400 i s available in industry s tandard
JEDEC-approved one-time programmable (OTP) PDIP,
SOIC (SOP), and TSOP packages. The device features
two-line control (CE
high-speed systems.
With high density 25 6K word or 512K byte storage capability, the AT27C400 allows firmware to be stored reliably and
to be accessed by the s ystem withou t the delay s of mass
storage media.
Atmel’s AT27C400 has additional features that ensure high
quality and efficient production use. The Rapid
ming Algori thm reduc es the tim e requi red to pro gram the
part and guarantees reliable programming. Programming
time is typically only 50
Identification Code electronically identifies the device and
manufacturer. This feature is used by industry standard
programming eq uipme nt to sel ect the pro per prog ramming
algorithms and voltages.
(Continued)
/VPP is asserted low (VIL), the
the lower 8 bits of the 16-bit
IL
, OE) to eliminate bus contention in
s/word. The Integrated Product
the upper 8 bits of the
IH
™
Program-
/V
PP
.
A
System Considerations
Switching between active and standby conditions via the
Chip Enable pin may produce tr ans ie nt v olta ge e xcur sion s.
Unless accommodated by the system design, these transients may exceed data sheet limits, resulting in device
non-conforman ce. At a mi nimum, a 0.1
low inherent inductance, ceramic capacitor should be utilized for each device. This capacitor shoul d be connected
between the V
close to the device as possible. Additionally, to stabilize the
supply voltage level on printed circuit boards with large
EPROM arrays, a 4.7
be utilized, agai n connec ted betwe en the V
terminals. This capacitor should be positioned as close as
possible to the point where the power supply is connected
to the array.
and Ground terminals of the device, as
CC
F bulk electrolytic capacitor should
F high frequency,
and Ground
CC
2
AT27C400
Block Diagram
Absolute Maximum Ratings*
AT27C400
Temperature Under Bias ......................-55°C to +125°C
Storage Temperature............................-65°C to +150°C
Voltage on Any Pin with
Respect to Ground ..............................-2.0V to +7.0V
Voltage on A9 with
Respect to Ground ...........................-2.0V to +14.0V
VPP Supply Voltage with
Respect to Ground ............................-2.0V to +14.0V
Integrated UV Erase Dose...................7258 W •sec/cm
*NOTICE:Stresses beyond those listed under “Absolute Maxi-
mum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional
operation of the device at these or any other conditions beyond those indicated in the operational sec-
(1)
tions of this specification is not implied. Exposure to
absolute maximum rating conditions for extended
periods may affect device reliability.
(1)
Note:1.Minimum voltage is -0.6V dc which undershoot to -
2.0V for pulses of less than 20 ns. Maximum output
(1)
2
(1)
X
(1)
X
(1)
X
(1)
X
(1)
X
AiV
AiV
(1)
X
(3)
A9 = V
H
A0 = VIH or V
A1 - A17 = V
pin voltag e is V
+7.0V for pulses of less than 20 ns.
PP
V
IH
V
IL
V
IL
XHigh Z
(5)
X
PP
PP
V
PP
V
IL
IL
IH
+ 0.75V dc which may ov ersho ot t o
CC
Outputs
O0 - O
D
OUT
D
OUT
D
OUT
7
O8 - O
14
D
OUT
High ZV
High ZV
High Z
D
IN
D
OUT
High Z
Identificatio
n
Code
O15/A-1
D
OUT
IH
IL
Notes:1.X can be VIL or VIH.
2.Refer to the programming characteristics tables in this data sheet.
= 12.0 ± 0.5V.
3.V
H
4.Two identifier words may be selected. All inputs are held low (VIL), except A9, which is set to VH, and A0, which is toggled
low (V
) to select the Manufacturer’s Identification word and high (VIH) to select the Device Code word.
IL
5.Standby VCC current (ISB) is specified with VPP = VCC. VCC > VPP will cause a slight increase in ISB.
3
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