Intel mcs-48 Crystal Oscillator Mode Driving from External Source, +-----t XTALl, Reset, Prog

108048/8748/8035L

CRYSTAL OSCILLATOR MODE DRIVING FROM EXTERNAL SOURCE

,---r----'-1 XTALl

1·6 mHz

0-15 pF

(INCLUDES XTAL SOCKET, STRAy)

'-----t------"l3XTAL2

15-25 pF I

(INCLUDES SOCKET, STRAY) -=-

CRYSTAL SERIES RESISTANCE SHOULD BE <751'1AT 6 MHz; <180Q AT 3.8 MHz.

+5V

4701'1

}>--+----"-t XTALl

+5V

4701'1

L-_--+-_-"-j XTAL2

BOTH Xl AND X2 SHOULD BE DRIVEN.

RESISTORS TO Vee ARE NEEDED TO ENSURE V,H =3.BV IF TTL CIRCUITRY IS USED. THE MINIMUM HIGH AND THE MINIMUM LOW TIMES ARE 45%.

LC OSCILLATOR MODE

-"-	~	NOMINALf
45 flH	20 pF	5.2 MHz
120 J.lH	20 pF	3.2 MHz

...--..--"'1XTALl

C,=C+3Cpp

2

Cpp::::: 5-10 pF PIN·TO·PIN

'----+--"'1XTAL2 CAPACITANCE

EACH C SHOULD BE APPROXIMATELY 20 pF,lNCLUDING STRAY CAPACITANCE.

PROGRAMMING, VERIFYING, AND ERASING THE 8748 EPROM

Programming Verification

In brief, the programming process consists of: activat- ing the program mode, applying an address, latching the address, applying data, and applying a programming pulse. Each word is programmed completely before moving on to the next and is followed by a verification step. The following is a list of the pins used for program- ming and a description of their functions:

Pin	Function
XTAL1	Clock Input (1 to 6 MHz)
RESET	Initialization and Address Latching
TEST 0	Selection of Program or Verify Mode
EA	Activation of ProgramlVerify Modes
BUS	Address and Data Input
	Data Output during Verify
P20-1	Address Input
Voo	Programming Power Supply
PROG	Program Pulse Input

WARNING:

An attempt to program a mis-socketed 8748 will result in severe damage to the part. An indication of a properly socketed part is the appearance of the ALE clock out- put. The lack of this clock may be used to disable the programmer.

The ProgramlVerify Sequence is:

1.Voo=5V, clock applied or internal oscillator oper- ating, RESET=OV, TEST 0=5V, EA=5V, BUS and PROG floating:

2.Insert 8748 in programming socket.

3.TEST 0 = OV (select program mode).

4.EA = 23V (activate program mode).

5.Address applied to BUS and P20-1.

6.RESET = 5V (latch address).

7.Data applied to BUS.

8.Voo = 25V (programming power).

9.PROG = OV followed by one 50 ms pulse to 23 V.

10.Voo=5V.

11.TEST 0 = 5V (verify mode).

12.Read and verify data on BUS.

13.TEST 0 = OV.

14.RESET = OV and repeat from step 5.

15.Programmer should be at conditions of step 1 when 8748 is removed from socket.

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