Texas Instruments TMS320

TMS320E25

SPRS010B— MAY 1987— REVISED NOVEMBER 1990

POST OFFICE BOX 1443 •HOUSTON, TEXAS 77001

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

NAME†TMS320E25

PIN TMS27C64

PIN PROGRAM PROGRAM

VERIFY PROGRAM

INHIBIT READ OUTPUT

DISABLE

E 22 20 VIL VIL VIH VIL VIL

G 42 22 VIH PULSE X PULSE VIH

PGM 41 27 PULSE VIH X VIH VIH

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

RS 65 14 VSS VSS VSS VSS VSS

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

†In accordance with TMS27C64.

LEGEND;

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

VPP = 12.5 V ± 0.5 V; VCC = 5 ± 0.25 V; X = don’t care

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.

ADVANCE INFORMATION