Texas Instruments TMS320E25 Programming Mode Levels, Erasure, Fast programming, Signal

TMS320E25

ADVANCE INFORMATION

SPRS010B Ð MAY 1987 Ð REVISED NOVEMBER 1990

Table 5 shows the programming levels required for programming, verifying and reading the EPROM cell. The paragraphs following the table describe the function of each programming level.

Table 5. TMS320E25 Programming Mode Levels

SIGNAL

TMS320E25

TMS27C64

PROGRAM

PROGRAM

PROGRAM

READ

OUTPUT

NAME ²

PIN

PIN

VERIFY

INHIBIT

DISABLE

22

20

VIL

VIL

VIH

VIL

VIL

E

42

22

VIH

X

VIH

G

PULSE

PULSE

41

27

VIH

X

VIH

VIH

PGM

PULSE

VPP

25

1

VPP

VPP

VPP

VCC

VCC

VCC

61,35

28

VCC + 1

VCC + 1

VCC + 1

VCC

VCC

VSS

27,44,10

14

VSS

VSS

VSS

VSS

VSS

CLKIN

52

14

VSS

VSS

VSS

VSS

VSS

65

14

VSS

VSS

VSS

VSS

VSS

RS

EPT

24

26

VSS

VSS

VSS

VSS

VSS

Q1-Q8

18-11

11-13,15-19

DIN

QOUT

HI-Z

QOUT

HI-Z

A12-A10

40-38

2,23,21,

ADDR

ADDR

X

ADDR

X

A9-A7

37,36,34

24,25,3

ADDR

ADDR

X

ADDR

X

A6

33

4

ADDR

ADDR

X

ADDR

X

A5

32

5

ADDR

ADDR

X

ADDR

X

A4

31

3

ADDR

ADDR

X

ADDR

X

A3-A0

30-28,26

7-10

ADDR

ADDR

X

ADDR

X

²In accordance with TMS27C64.

LEGEND;

VIH = TTL high level; VIL = TTL low level; ADDR = byte address bit

±0.5 V; VCC = 5 ± 0.25 V; X = don't careVPP = 12.5 V

PULSE = low-going TTL level pulse; DIN = byte to be programmed at ADDR

QOUT = byte stored at ADDR; RBIT = ROM protect bit.

erasure

Before programming, the device is erased by exposing the chip through the transparent lid to high-intensity ultraviolet light (wavelength 2537 Å). The recommended minimum exposure dose (UV-intensity ⋅ exposure-time) is 15 W•s/cm2. A typical 12 mW/cm2, filterless UV lamp will erase the device in 21 minutes. The lamp should be located approximately 2.5 cm above the chip during erasure. After erasure, all bits are in the high state. Note that normal ambient light contains the correct wavelength for erasure. Therefore, when using the TMS320E25, the window should be covered with an opaque label.

fast programming

After erasure (all memory bits in the cell are logic one), logic zeroes are programmed into the desired locations. The fast programming algorithm, shown in Figure 10, is normally used to program the entire EPROM contents, although individual locations may be programmed separately. A programmed logic zero can be erased only by ultraviolet light. Data is presented in parallel (eight bits) on pins Q8-Q1. Once addresses and data are stable, PGM is pulsed. The programming mode is achieved when VPP = 12.5 V, PGM = VIL, VCC = 6 V, G = VIH, and E = VIL More than one TMS320E25 can be programmed when the devices are connected in parallel. Locations can be programmed in any order.

Programming uses two types of programming pulses: prime and final. The length of the prime pulse is 1 ms. After each prime pulse, the byte being programmed is verified. If correct data is read, the final programming pulse is applied; if correct data is not read, an additional 1-ms prime pulse is applied up to a maximum of 15 times. The final programming pulse is 4 ms times the number of prime programming pulses applied. This sequence of programming and verification is performed at VCC = 6 V, and VPP = 12.5 V. When the full fast programming routine is complete, all bits are verified with VCC = VPP = 5 V.

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