Intel mcs-48 manual Voo, Lcoscillator Mode, Programming Verification

M80481 M87481 M8035L

CRYSTAL OSCILLATOR MODE

Cl

~1,,::~:-_~___""'___2'-i XTAL 1=

-=-		I
		1-_---'1___+-__...;31XTAL2
		C3
Cl	;	SpF ± 12pF + STRAY < SpF
C2	;	CRYSTAL + STRAY < 8pF
C3	= 20pF ± 1pF + STRAY < SpF

LCOSCILLATOR MODE

..h.	.£.	~
45 "H	20 pF	5.2 MHz
120 "H	20 pF	3.2 MHz

, --- r --- j XTAU

c'= C + 3Cpp 2

Cpp ::::: 5 - 10 pF PIN·TO·PIN

' ---- 4 - _ --XTAL2jCAPAC ITANCE

CRYSTAL SERIES RESISTANCE SHOULD BE LESS THAN 1SQ AT 8MHz; LESS	EACH C SHOULD BE APPROXIMATEl Y 20 pF, INCLUDING STRAY CAPACITANCE.
THAN 180Q AT 3.8MHz.

DRIVING FROM EXTERNAL SOURCE

+SV

470Q

»---+-----'-1 XTAL1

+SV

470Q

'---~--'-i XTAL2

FOR XTAL 1 AND XTAL 2 DEFINE "HIGH" AS VOLTAGES ABOVE 1.8V AND "LOW" AS VOLTAGES BELOW 1.6V. THE DUTY CYCLE REQUIREMENTS FOR EXTERNALLY DRIVING XTAL 1 AND XTAL 2 USING THE CIRCUIT SHOWN ABOVE ARE AS FOLLOWS:

FOR THE 8048. XTAL 1 MUST BE HIGH 35-6S% OF THE PERIOD AND XTAL 2 MUST

BE HIGH 3S-65% OF THE PERIOD.

FOR THE 8748. XTAL MUST BE HIGH 45·50% OF THE PERIOD AND XTAL 2 MUST BE HIGH SO·SS% OF THE PERIOD.

RISE AND FALL TIMES MUST NOT EXCEED 20 ns.

PROGRAMMING, VERIFYING, AND ERASING THE 8748 EPROM

Programming Verification

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

Pin	Function
XTALl	Clock Input (1 to 6MHz)
Reset	Initialization and Address Latching
Test 0	Selection of Program or Verify Mode
EA	Activation of ProgramNerify 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 missocketed 8748 will reSUlt in severe damage to the part. An indication of a properly socketed part is the appearance of the ALE clock output. The lack of this clock may be used to disable the prQgrammer.

The ProgramNerify sequence is:

1.~5v, Clock applied or internal oscillator operating, RESET =OIl, TEST 0 =5v, EA =5v, 8US 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 P2()'1

6.RESET = 5v (latch address)

7.Oata appl ied to BUS

8.VOO= 25v (programming power)

9.PROG = 011 followed by one SOms pulse to 23V

10.VOO = 5v

11.TEST 0 = 5v (verify mode)

12.Read and verify data on BUS

13.TEST 0= 011

14.RESET = 011 and repeat from step 5

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

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