HT27LC020 Просмотр технического описания (PDF) - Holtek Semiconductor
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HT27LC020 Datasheet PDF : 15 Pages
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HT27LC020
Functional Description
Operation Mode
All the operation modes are shown in the table following.
Mode
CE
OE PGM A0
Read
Output Disable
Standby (TTL)
VIL
VIL
X (2)
X
VIL
VIH
X
X
VIH
X
X
X
Standby (CMOS)
Program
Program Verify
Product Inhibit
Manufacturer Code (3)
Device Code (3)
VCC±0.3V
X
X
X
VIL
VIH
VIL
X
VIL
VIL
VIH
X
VIH
X
X
X
VIL
VIL
X
VIL
VIL
VIL
X
VIH
A1
A9
VPP
X
X
VCC
X
X
VCC
X
X
VCC
X
X
VCC
X
X
VPP
X
X
VPP
X
X
VPP
VIH
VH (1) VCC
VIH
VH (1) VCC
Notes: (1) VH = 12.0V±0.5V
(2) X=Either VIH or VIL
(3) For Manufacturer Code and Device Code, A1=VIH, When A1=VIL, both codes will read 7F
Output
Dout
High Z
High Z
High Z
DIN
DOUT
High Z
1C
02
Programming of the HT27LC020
When the HT27LC020 is delivered, the chip has all
2048K bits in the ²ONE², or HIGH state. ²ZEROs² are
loaded into the HT27LC020 through programming.
The programming mode is entered when 12.5±0.2V is ap-
plied to the VPP pin, OE is at VIH, and CE and PGM are
VIL. For programming, the data to be programmed is ap-
plied with 8 bits in parallel to the data pins.
The programming flowchart in Figure 3 shows the fast
interactive programming algorithm. The interactive al-
gorithm reduces programming time by using 30ms to
105ms programming pulses and giving each address
only as many pulses as is necessary in order to reliably
program the data. After each pulse is applied to a given
address, the data in that address is verified. If the data
is not verified, additional pulses are given until it is veri-
fied or until the maximum number of pulses is reached
while sequencing through each address of the
HT27LC020. This process is repeated while sequenc-
ing through each address of the HT27LC020. This part
of the programming algorithm is done at VCC=6.0V to
assure that each EPROM bit is programmed to a suffi-
ciently high threshold voltage. This ensures that all bits
have sufficient margin. After the final address is com-
pleted, the entire EPROM memory is read at
VCC=VPP=3.3±0.3V to verify the entire memory.
Program inhibit Mode
Programming of multiple HT27LC020 in parallel with dif-
ferent data is also easily accomplished by using the Pro-
gram Inhibit Mode. Except for CE, all like inputs of the
parallel HT27LC020 may be common. A TTL low-level pro-
gram pulse applied to an HT27LC020 CE input with VPP=
12.5±0.2V, PGM Low, and OE High will program that
HT27LC020. A high-level CE input inhibits the HT27LC020
from being programmed.
Program Verify Mode
Verification should be performed on the programmed
bits to determine whether they were correctly pro-
grammed. The verification should be performed with
OE and CE at VIL, PGM at VIH, and VPP at its program-
ming voltage.
Auto Product Identification
The Auto Product Identification mode allows the read-
ing out of a binary code from an EPROM that will identify
its manufacturer and the type. This mode is intended for
programming to automatically match the device to be
programmed with its corresponding programming algo-
rithm. This mode is functional in the 25°C±5°C ambient
temperature range that is required when programming
the HT27LC020.
To activate this mode, the programming equipment must
force 12.0±0.5V on the address line A9 of the
HT27LC020. Two identifier bytes may then be sequenced
from the device outputs by toggling address line A0 from
VIL to VIH, when A1=VIH. All other address lines must be
held at VIH during Auto Product Identification mode.
Byte 0 (A0=VIL) represents the manufacturer code, and
byte 1 (A0=VIH), the device code. For HT27LC020,
these two identifier bytes are given in the Mode Select
Table. All identifiers for the manufacturer and device
codes will possess odd parity, with the MSB (DQ7) de-
fined as the parity bit. When A1=VIL, the HT27LC020
will read out the binary code of 7F, continuation code, to
signify the unavailability of manufacturer ID codes.
Rev. 1.50
5
December 8, 2003
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