Rainbow Electronics W78C54 User Manual

W78C54

8-BIT MICROCONTROLLER

GENERAL DESCRIPTION

The W78C54 is a derivative of the W78C52 microcontroller family that provides extended internal
ROM. The chip has 16K bytes of mask ROM and 256 bytes of RAM.

This device provides an enhanced architecture that makes it more powerful and suitable for a variety
of applications for general control systems. It provides on-chip 16KB mask ROM to accommodate
large program codes, 256-bytes of non-volatile on-chip RAM, four 8-bit I/O ports, one 4-bit I/O port,
three 16-bit timer/counters, eight sources with two-level interrupt structures, and on-chip oscillator
clock circuits.

FEATURES

• DC to 40 MHz extensive operating frequency

• 256-byte on-chip scratch pad RAM

• 16K-byte on-chip mask ROM

• 64K-byte address space for external Program Memory

• 64K-byte address space for external Data Memory

• Three 16-bit timer/counters

Four 8-bit bit-addressable I/O ports

•

• One extra 4-bit bit-addressable I/O port, additional INT2/ INT3

(Available on 44-pin PLCC/QFP package)

• Eight-source, two priority-level interrupts

• Low EMI emission mode

• Built-in programmable power-saving modes - Idle mode & Power-down mode

• Packages:

− DIP 40: W78C54-16/24/40

− PLCC 44: W78C54P-16/24/40

− QFP 44: W78C54F-16/24/40

− TQFP 44: W78C54M-16/24/40

Publication Release Date: December 1997

- 1 - Revision A2

PIN CONFIGURATIONS

40-Pin DIP (W78C54)

T2, P1.0

T2EX, P1.1

P1.2

P1.3
P1.4

P1.5

P1.6

P1.7
RST

RXD, P3.0
TXD, P3.1

INT0, P3.2

INT1, P3.3

T0, P3.4
T1, P3.5

WR, P3.6

RD, P3.7

XTAL2
XTAL1

VSS

W78C54

VCC1

2

3
4

5
6

7

8

9
10

11

12
13

14
15

16

17
18

19

20

40

39

P0.0, AD0

38

P0.1, AD1

37

P0.2, AD2
P0.3, AD3

36
35

P0.4, AD4

34

P0.5, AD5
P0.6, AD6

33

P0.7, AD7

32

31

EA
ALE

30
29

PSEN

28

P2.7, A15
P2.6, A14

27
26

P2.5, A13

25

P2.4, A12

24

P2.3, A11

23

P2.2, A10
P2.1, A9

22
21

P2.0, A8

44-Pin PLCC (W78C54P)

T
2
E
X
,
P

P

P

P

1

1

1

1

.

.

.

.

1

3

4

2

6543

7

P1.5

8

P1.6

9

P1.7

10

RST

RXD, P3.

INT2, P4.3

TXD, P3.1

INT0, P3.2

INT1, P3.3

T0, P3.4

T1, P3.5

11

12

13
14

15
16
17

P

P

X

X

3

3

T

T

.

.

A

A

6

7

L

L

,

,

2

1

/

/

W

R

R

D

/
I

A

N

T

D

T

2

0

3

,

,

,

P

P

P

1

0

V

4

C

.

.

.

0

0

C

2

2 1 44 43 42

P

P

V

P

S

2

2

4

S

.

.

.

0

1

0

,

,

A

A

8

9

44-Pin QFP/TQFP (W78C54F/W78C54M)

/

T

I

P
1
.
4

P
3
.
6
,
/
W
R

P

P

1

1

.

.

3

2

43 42 41

X

P

T

3

A

.

L

7

2

,
/
R
D

2
E

T

X

2

,

,

P

P

1

1

.

.

1

0

40 39 38 37 36

X

V

T

S
S

A
L
1

A

A

A

D

D

D

3

1

2

,

,

,
P

P

P

0

0

0

.

.

.

3

1

2

40

41

P

P
2

2
.

.
2

3
,

,

A

A
1

1
1

0

P0.4, AD4

39
38

P0.5, AD5

37

P0.6, AD6

36

P0.7, AD7

35

EA

34

P4.1

33

ALE

32

PSEN

31

P2.7, A15

30

P2.6, A14

29

P2.5, A13

2827262524232221201918

P
2
.
4
,
A
1
2

RXD, P3.0

INT2, P4.3

TXD, P3.1

INT0, P3.2

INT1, P3.3

T0, P3.4
T1, P3.5

P1.5

P1.6

P1.7

RST

1
2

3

4
5

6
7
8
9
10

11

A

A

A

N
T
3
,
P
4
.
2

P
4
.
0

A

D

D

D

D

1

3

0

2

,

,

,

,

P

P

P

P

0

0

0

0

V
C
C

P
2
.
0
,
A
8

.

.

.

.

1

3

0

2

34

3544

P

P

P

2

2

2

.

.

.

1

3

2

,

,

,
A

A

A

9

1

1
1

0

P0.4, AD4

33
32

P0.5, AD5

31

P0.6, AD6

30

P0.7, AD7

29

EA

28

P4.1

27

ALE

26

PSEN

25

P2.7, A15

24

P2.6, A14

23

P2.5, A13

2221201918171615141312

P
2
.
4
,
A
1
2

- 2 -

W78C54

PIN DESCRIPTION

SYMBOL TYPE DESCRIPTIONS

EA I EXTERNAL ACCESS ENABLE: This pin forces the processor to execute out

of external ROM. The ROM address and data will not be present on the bus if

EA pin is high and the program counter is within the 16 KB area.

the
Otherwise they will be present on the bus.

PSEN O H

ALE O H ADDRESS LATCH ENABLE: ALE is used to enable the address latch that

RST I L RESET: A high on this pin for two machine cycles while the oscillator is

XTAL1 I CRYSTAL 1: This is the crystal oscillator input. This pin may be driven by an

XTAL2 O CRYSTAL 2: This is the crystal oscillator output. It is the inversion of XTAL1.

VSS I GROUND: ground potential.

VDD I POWER SUPPLY: Supply voltage for operation.

P0.0−P0.7

P1.0−P1.7

P2.0−P2.7

P3.0−P3.7

P4.0−P4.3

INT2 (P4.3) I H External interrupt 2: An extra interrupt input source. It cascades to pin P4.3

INT3 (P4.2) I H External interrupt 3: An extra interrupt input source. It cascades to pin P4.2

I/O D PORT 0: Function is the same as that of the standard 8052.

I/O H PORT 1: Function is the same as that of the standard 8052.

I/O H PORT 2: Function is the same as that of the standard 8052.

I/O H PORT 3: Function is the same as that of the standard 8052.

I/O H PORT 4: A 4-bit bi-directional parallel port and bit-addressable with internal

PROGRAM STORE ENABLE: PSEN enables the external ROM data in the
Port 0 address/data bus.

When internal ROM access is performed, no PSEN strobe signal outputs
originate from this pin.

separates the address from the data on Port 0. ALE runs at 1/6th of the
oscillator frequency. An ALE pulse is omitted during external data memory
accesses.

running resets the device.

external clock.

pull-ups. Pin P4.3 and P4.2 have alternative function as external interrupt
(INT2/INT3) source input.

internally.

internally.

* Note : TYPE I: input, O: output, I/O: bi-directional, H: pull-high, L: pull-low, D: open drain

Publication Release Date: December 1997

- 3 - Revision A2

BLOCK DIAGRAM

W78C54

P1.0
~
P1.7

P3.0
~
P3.7

P4.0
~
P4.3

INT2

INT3

Port

1

Port

Port

Port 1

Latch

ACC

Interrupt

Timer

2

Timer

0

Timer

1

UART

3

4

Port 3

Latch

Port 4
Latch

Oscillator

PSW

Instruction

Decoder

&

Sequencer

Bus & Clock

Controller

ALU

Reset Block

T2T1

SFR RAM

Address

256 bytes

RAM & SFR

B

Stack

Pointer

Power control

Port 0

Latch

DPTR

Temp Reg.

PC

Incrementor

Addr. Reg.

16KB
ROM

Port 2

Latch

Port
0

Port
2

P0.0
~
P0.7

P2.0
~
P2.7

XTAL1 PSENALE GNDVCCRSTXTAL2

Figure 2. Architecture of the W78C54

- 4 -

W78C54

FUNCTIONAL DESCRIPTION

The W78C54 is pin-to-pin compatible with the W78C52, except that the internal 8K mask ROM has
been replaced with 16K of internal mask ROM. The processor supports 111 different opcodes and
references both 64K program address space and 64K data storage space.

Clock

The W78C54 is designed to be used with either a crystal oscillator or an external clock. Internally, the
clock is divided by two before it is used. This makes the W78C54 relatively insensitive to duty cycle
variations in the clock.

Crystal Oscillator

The W78C54 incorporates a built-in crystal oscillator. To make the oscillator work, a crystal is
connected across pins XTAL1 and XTAL2. In addition, a load capacitance of 30 pf (typically) must be
connected from each pin to ground. Resistor must also be connected from XTAL1 to XTAL2 to
provide a DC bias when the crystal frequency is above 24 MHz.

External Clock

An external clock should be connected to pin XTAL1. Pin XTAL2 should be left unconnected. The
XTAL1 input is a CMOS-type input, as required by the crystal oscillator. As a result, the external clock
signal should have an input one level greater than 3.5 volts.

Power Management

Idle Mode

The idle mode is entered by setting the IDLE bit in the PCON register. In the idle mode, the internal
clock to the processor is stopped. The peripherals and the interrupt logic continue to be clocked. The
processor will exit idle mode when either an interrupt or a reset occurs.

Power-down Mode

When the PD bit of the PCON register is set, the processor enters the power-down mode. In this
mode all of the clocks are stopped, including the oscillator. The only way to exit power-down mode is
by a reset.

Reset

The external RESET signal is sampled at S5P2. To take effect, it must be held high for at least two
machine cycles while the oscillator is running.

An internal trigger circuit in the reset line is used to deglitch the reset line when the
with an external RC network. The reset logic also has a special glitch removal circuit that ignores
glitches on the reset line.

During reset, the ports are initialized to FFH, the stack pointer to 07H, PCON (with the exception of
bit 4) to 00H, and all of the other SFR registers except SBUF to 00H. SBUF is not reset.

W78C54 is used

New Defined Peripheral

In order to be more suitable for I/O, an extra 4-bit bit-addressable port P4 and two external interrupt
INT2, INT3 has been added to either the PLCC or QFP 44 pin package. And description follows:

Publication Release Date: December 1997

- 5 - Revision A2

W78C54

1. INT2 / INT3

Two additional external interrupts, INT2 and INT3, whose functions are similar to those of external
interrupt 0 and 1 in the standard 80C52. The functions/status of these interrupts are
determined/shown by the bits in the XICON (External Interrupt Control) register. The XICON register
is bit-addressable but is not a standard register in the standard 80C52. Its address is at 0C0H. To
set/clear bits in the XICON register, one can use the "SETB (/CLR) bit" instruction. For example,
"SETB 0C2H" sets the EX2 bit of XICON.

2. PORT4

Another bit-address port P4 is also available except only 4 bits (P4<3:0>) can be used. This port
address is located at 0D8H with the same function as that of port P1,except the P4.3 and P4.2 are
alternative function pins. It can be used as general I/O pins or external interrupt input sources
(INT2/INT3).

Example:

P4 REG 0D8H

MOV P4, #0AH ; Output data "A" through P4.0−P4.3.

MOV A, P4 ; Read P4 status to Accumulator.

SETB P4.0 ; Set bit P4.0

CLR P4.1 ; Clear bit P4.1

Reduce EMI Emission

Because of the large on-chip mask-ROM, when a program is running in internal ROM space, the ALE
will be unused. The transition of ALE will cause noise, so it can be turned off to reduce the EMI
emission if it is useless. Turning off the ALE signal transition only requires setting the bit 0 of the
AUXR SFR, which is located at 08Eh. When ALE is turned off, it will be reactivated when the program
accesses external ROM/RAM data or jumps to execute an external ROM code. The ALE signal will
turn off again after it has been completely accessed or the program returns to internal ROM code
space..

POF Flag

The Power-Off-Reset flag is set by on-chip circuitry when the VCC level rises from 0 to 5V. The POF
bit can be set/cleared by software allowing a user to determine if the reset is the result of a power-on
or a warm up by external reset. To avoid effect of POF flag, the power voltage must remain above
3V.

Timers 0, 1, and 2

Timers 0, 1, and 2 each consist of two 8-bit data registers. These are called TL0 and TH0 for Timer 0,
TL1 and TH1 for Timer 1, and TL2 and TH2 for Timer 2. The TCON and TMOD registers provide
control functions for timers 0, 1. The T2CON register provides control functions for Timer 2. RCAP2H
and RCAP2L are used as reload/capture registers for Timer 2.

The operations of Timer 0 and Timer 1 are the same as in the W78C51. Timer 2 is a special feature
of the W78C52C: it is a 16-bit timer/counter that is configured and controlled by the T2CON register.
Like Timers 0 and 1, Timer 2 can operate as either an external event counter or as an internal timer,
depending on the setting of bit C/T2 in T2CON. Timer 2 has three operating modes: capture, auto­reload, and baud rate generator. The clock speed at capture or auto-reload mode is the same as that
of Timers 0 and 1.

- 6 -

W78C54

DESCRIPTIONS OF THE SPECIAL FUNCTION REGISTERS (SFRS)

SYM. DEFINITION

B B register F0H (F7) (F6) (F5) (F4) (F3) (F2) (F1) (F0) 00000000B

ACC Accumulator E0H (E7) (E6) (E5) (E4) (E3) (E2) (E1) (E0) 00000000B

P4* Port 4 D8H - - - - (DB)

PSW Program status word D0H (D7)CY(D6)AC(D5)F0(D4)

TH2 T2 reg. high CDH 00000000B

TL2 T2 reg. low CCH 00000000B

RCAP2H T2 capture high CBH 00000000B

RCAP2L T2 capture low CAH 00000000B

T2CON Timer 2 control C8H (CF)

XICON* External interrupt

control

IP Interrupt priority B8H - - PT2 PS PT1 PX1 PT0 PX0 xx000000B

P3 Port 3 B0H (B7)RD(B6)WR(B5)T1(B4)T0(B3)

IE Interrupt enable A8H (AF)EA(AE)-(AD)

P2 Port 2 A0H (A7)

SBUF Serial buffer 99H xxxxxxxxB

SCON* Serial control 98H (9F)

P1* Port 1 90H (97) (96) (95) (94) (93) (92) (91)

AUXR* Auxiliary 8EH - - - - - - - AO xxxxxxx0B

TH1 Timer high 1 8DH 00000000B

TH0 Timer high 0 8CH 00000000B

TL1 Timer low 1 8BH 00000000B

TL0 Timer low 0 8AH 00000000B

TMOD Timer mode 89H GATE C/T M1 M0 GATE C/T M1 M0 00000000B

TCON Timer control 88H (8F)

PCON* Power control 87H SMOD

DPH Data pointer high 83H 00000000B

DPL Data pointer low 82H 00000000B

SP Stack pointer 81H 00000111B

P0 Port 0 80H (87) (86) (85) (84) (83) (82) (81) (80) 11111111B

ADDR.

TF2

C0H (C7)

PX3

A15

SM0/FE

TF1

MSB BIT ADDRESS, SYMBOL LSB RESET

(DA)

(D9) (D8) xxxx0000B

INT2

INT3

(D3)

(D2)OV(D1)-(D0)P00000000B

RS1

RS0

(CE)

(CD)

(CC)

(CB)

EXF2

(C6)

EX3

(A6)

A14

(9E)

SM1

(8E)

TR1

SMOD0

(CA)

RCLK

TCLK

EXEN2

(C5)

(C4)

(C3)

IE3

IT3

PX2

INT1

INT0

(AC)ES(AB)

ET2

(A5)

A13

(9D)

SM2

(8D)

TF0

- POF+ GF1 GF0 PD IDL 00xxxx00B

(A4)

A12

(9C)

REN

(8C)

TR0

ET1

(A3)

A11

(9B)

TB8

(8B)

IE1

(C9)

TR2

(C2)

EX2

(B2)

(AA)

EX1

(A2)

A10

(9A)

RB8

(8A)

IT1

CP/RL2

C/T2

(C1)

IE2

(B1)

TXD

(A9)

ET0

(A1)A9(A0)A811111111B

(99)TI(98)RI00000000B

T2EX

(89)

RXD

IE0

(C8)

00000000B

(C0)

00000000B

IT2

(B0)

11111111B

(A8)

00000000B

EX0

(90)T211111111B

(88)

00000000B

IT0

Publication Release Date: December 1997

- 7 - Revision A2

W78C54

Note: In column BIT_ADDRESS, SYMBOL, containing ( ) item means the bit address.

* SFRs modified or added to the W78C52. + Reset value depends on reset condition.

W78C54 SFRs address location map:

F8 FF

F0 + B F7

E8 EF

E0 + ACC E7

D8 +P4 DF

D0 + PSW D7

C8 +T2CON RCAP2L RCAP2H TL2 TH2 CF

C0 +XICON C7

B8 + IP BF

B0 + P3 B7

A8 + IE AF

A0 + P2 A7

98 + SCON SBUF 9F

90 + P1 97

88 + TCON TMOD TL0 TL1 TH0 TH1 AUXR 8F

80 +P0 SP DPL DPH PCON 87

Notes:

1. + SFR is bit-addressable.

2. is additional defined function.

Power-off Flag

***PCON - Power Control (87H)

SMOD SMOD0

-

POF

SMOD: Double baud rate bit. When set to a 1, the baud rate is doubled when the serial port is

being used in either modes 1, 2, 3.

SMOD0: Enable FE bit in SCON. This bit is an alternative switch of SM0 and FE (Frame Error)
bit. When set to a 1, SCON.7 means a FE bit, otherwise a SM0 bit.

POF: Power off flag. Bit is set by hardware when power on reset. It can be cleared by software

to determine chip reset is a warm boot or cold boot.

GF1, GF0: These two bits are general-purpose flag bits for the user.

PD: Power down mode bit. Set it to enter power down mode.

IDL: Idle mode bit. Set it to enter idle mode.

The power-off flag is located at PCON.4. This bit is set when V
be used to determine if a reset is a warm boot or a cold boot if it is subsequently reset by software.

GF1 GF0 PD IDL

DD has been applied to the part. It can

- 8 -

* Interrupts

***IE - Interrupt Enable (A8H)

EA - ET2 ES ET1 EX1 ET0 EX0

EA: Lobal interrupt enable flag

ET2: Timer 2 overflow interrupt enable

ES: Serial port interrupt enable

EX1: External interrupt 1 enable

ET1: Timer 1 overflow interrupt enable

EX0: External interrupt 0 enable

***IP - Interrupt Priority (B8H)

- - PT2 PS PT1 PX1 PT0 PX0

PT2: Timer 2 interrupt priority high if set

PS: Serial port priority high if set

PT1: Timer 1 interrupt priority high if set

PX1: External interrupt 1 priority high if set

PT0: Timer 0 interrupt priority high if set

PX0: External interrupt 0 priority high if set

W78C54

***XICON - External Interrupt Control (C0H)

PX3 EX3 IE3 IT3 PX2 EX2 IE2 IT2

PX3: External interrupt 3 priority high if set

EX3: External interrupt 3 enable if set

IE3: If IT3 = 1, IE3 is set/cleared automatically by hardware when interrupt is detected/serviced

IT3: External interrupt 3 is falling-edge/low-level triggered when this bit is set/cleared by software

PX2: External interrupt 2 priority high if set

EX2: External interrupt 2 enable if set

IE2: If IT2 = 1, IE2 is set/cleared automatically by hardware when interrupt is detected/serviced

IT2: External interrupt 2 is falling-edge/low-level triggered when this bit is set/cleared by software

The W78C54 supports an eight-source and a four-priority-level interrupt architectures. Besides the
SFRs of IP and IE to control the six-source of the standard 8052 interrupt functions. There is an
another SFR (XICON) to control the extra two-source of the external interrrupt (INT2 and INT3). This
priority scheme is formed by combining IPH with IP to determine the priority of each interrupt. Except

the INT2 and INT3, they are not defined in IP

SFR but in XICON.

Publication Release Date: December 1997

- 9 - Revision A2

Following tables show the interrupt informations and priority definitions.

Eight-source interrupt informations:

W78C54

INTERRUPT

SOURCE

External Interrupt 0 03H 0 (highest) IE.0 TCON.IT0

Timer/Counter 0 0BH 1 IE.1 -

External Interrupt 1 13H 2 IE.2 TCON.IT1

Timer/Counter 1 1BH 3 IE.3 -

Serial Port 23H 4 IE.4 -

Timer/Counter 2 2BH 5 IE.5 -

External Interrupt 2 33H 6 XICON.EX2 XICON.IT2

External Interrupt 3 3BH 7 (lowest) XICON.EX3 XICON.IT3

VECTOR

ADDRESS

POLLING

SEQUENCE WITHIN

PRIORITY LEVEL

ENABLE

REQUIRED

SETTINGS

INTERRUPT

TYPE

EDGE/LEVEL

*Timer/Counter

***TL0, TH0, TL1, TH1, TL2, TH2, RCAP2L, RCAP2H

***TMOD - Timer 0, 1 mode (89H)

GATE C//T M1 M0 GATE C//T M1 M0

TIMER0

TIMER1

GATE: Gating control. When set, Timer/counter x is enabled only while INTx pin is high and TRx

control pin is set. When cleared, Timer x is enabled whenever the TRx conrol bit is set.

C//T: Timer or Counter Selector. Cleared for timer operation. Set for counter operation.

M1 M0: Operating Mode

0 0: 13-bit Timer/Counter.

0 1: 16-bit Timer/Counter.

1 0: 8-bit auto-reload Timer/Counter. THx holds a value which is to be reloaded into TLx

each time it overflows.

1 1: Timer 0: TL0 is an 8-bit timer/counter controlled by the standard Timer 0 control bits.

TH0 is an 8-bit timer only controlled by Timer 1 control bits.

Timer 1: Timer/counter 1 stopped.

***TCON - Timer 0, 1 Control (88H)

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

TF1: Timer 1 overflow flag. Set by hardware on timer/counter overflow. cleared by hardware when

processor vectors to interrupt routine.

- 10 -

W78C54

TR1: Timer 1 run control bit. Set/cleared by software to turn timer/counter on or off.

TF0: Timer 0 overflow flag. Set by hardware on timer/counter overflow. Cleared by hardware when

processor vectors to interrupt routine.

TR0: Timer 0 run control bit. Set/cleared by software to turn timer/counter on or off.

IE1: Interrupt 1 edge flag. Set by hardware when external interrupt edge detected. Cleared when

interrupt processed.

IT1: Interrupt 1 type control bit. Set/cleared by software to specify falling edge/low level triggered

external interrupt.

IE0: Interrupt 0 edge flag. Set by hardware when external interrupt edge detected. Cleared when

interrupt processed.

IT0: Interrupt 0 type control bit. Set/cleared by software to specify falling edge/low level triggered

external interrupt.

***T2CON - Timer 2 Control (C8H)

TF2 EXF2 RCLK TCLK EXEN2 TR2 C//T CP//RL2

TF2: Timer 2 overflow flag. Set by a Timer 2 overflow and must be cleared by software. TF2 will

not be set when RCLK = 1 or TCLK = 1.

EXF2: Timer2 external flag. Set when either a capture or reload is caused by a negative transition

on T2EX and EXEN2 = 1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU
to vector to the Timer 2 interrupt routine. EXF2 must be cleared by software.

RCLK: Receive clock flag. RCLK = 1 causes the serial port to use Timer 2 overflow pulses for its

receive clock in mode 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the

receive clock.

TCLK: Transmit clock flag. TCLK = 1 causes the serial port to use Timer 2 overflow pulses for its

transmit clock in mode 1 and 3. TCLK = 0 causes Timer 1 overflow to be used for the
transmit clock.

EXEN2: Timer 2 external enable flag. EXEN2 = 1 allows a capture or reload to occur as a result of a

negative transition on T2EX if Timer 2 is not used to clock the serial port. EXEN2 = 0

causes Timer 2 to ignore events at T2EX.

TR2: TR2 = 1/0: turns on/off Timer 2.

C//T: Timer or Counter select. Set 1/0 for external event counter(falling edge triggered)/inter
timer.

CP//RL2: Capture/reload flag.

*Reduced EMI Mode

The AO bit in the AUXR register, when set, disables the ALE output.

***AUXR - Auxiliary Register (8EH)

-------AO

AO: Turn off ALE output.

Publication Release Date: December 1997

- 11 - Revision A2

W78C54

ABSOLUTE MAXIMUM RATINGS

PARAMETER SYMBOL MIN. MAX. UNIT

DC Power Supply VCC−VSS -0.3 +7.0 V

Input Voltage VIN VSS -0.3 VCC +0.3 V

Operating Temperature TA 070

Storage Temperature TST -55 +150

Note: Exposure to conditions beyond those listed under Absolute Maximum Ratings may adversely affect the life and reliability

of the device.

DC CHARACTERISTICS

(VDD−VSS = 5V ±10%, TA = 25°C, Fosc = 20 MHz, unless otherwise specified.)

PARAMETER SYM. SPECIFICATION UNIT TEST CONDITIONS

MIN. MAX.

Operating Voltage VDD 4.5 5.5 V

Operating Current IDD - 20 mA No load

V

DD = 5.5V

Idle Current IIDLE - 6 mA Idle mode

V

DD = 5.5V

Power Down Current IPWDN -50

Input Current

IIN1 -50 +10

P1, P2, P3, P4

Input Current

IIN2 -10 +300

RST

Input Leakage Current

I

LK -10 +10

P0, EA

Logic 1 to 0 Transition

ITL [*4] -500 -200

Current

P1, P2, P3, P4

Input Low Voltage

VIL1 0 0.8 V VDD = 4.5V

P0, P1, P2, P3, P4, EA

Input Low Voltage

VIL2 0 0.8 V VDD = 4.5V

RST

Input Low Voltage

VIL3 0 0.8 V VDD = 4.5V

XTAL1[*4]

µA

µA

µA

µA

µA

Power-down mode

V

DD = 5.5V

VDD = 5.5V

V

IN = 0V or VDD

VDD = 5.5V

0 < V

IN < VDD

VDD = 5.5V

IN < VDD

0V < V

VDD = 5.5V

V

IN = 2.0V

°C

°C

- 12 -

W78C54

DC Characteristics, continued

PARAMETER SYM. SPECIFICATION UNIT TEST CONDITIONS

MIN. MAX.

Input High Voltage

P0, P1, P2, P3, P4, EA

Input High Voltage

RST

Input High Voltage

XTAL1 [*4]

Output Low Voltage

P1, P2, P3, P4

Output Low Voltage
P0, ALE, PSEN [*3]

Sink Current
P1, P2, P3, P4

Sink Current
P0, ALE, PSEN

Output High Voltage
P1, P2, P3, P4

Output High Voltage
P0, ALE, PSEN [*3]

Source Current
P1, P2, P3, P4

Source Current
P0, ALE, PSEN

Notes:

*1. RST pin is a Schmitt trigger input. RST has internal pull-low resistors of about 30 KΩ.
*3. P0, ALE and /PSEN are tested in the external access mode.
*4. XTAL1 is a CMOS input.
*5. Pins of P1, P2, P3, P4 can source a transition current when they are being externally driven from 1 to 0. The transition

current reaches its maximum value when V

VIH1 2.4 VDD +0.2 V VDD = 5.5V

VIH2 3.5 VDD +0.2 V VDD = 5.5V

VIH3 3.5 VDD +0.2 V VDD = 5.5V

VOL1 - 0.45 V VDD = 4.5V

I

OL = +2 mA

VOL2 - 0.45 V VDD = 4.5V

OL = +4 mA

I

ISK1 48mAVDD = 4.5V

Vs = 0.45V

ISK2 10 14 mA VDD = 4.5V

Vs = 0.45V

VOH1 2.4 - V VDD = 4.5V

I

OH = -100 µA

VOH2 2.4 - V VDD = 4.5V

I

OH = -400 µA

ISR1 -120 -180

µA

VDD = 4.5V
Vs = 2.4V

ISR2 -10 -14 mA VDD = 4.5V

Vs = 2.4V

IN approximates to 2V.

AC CHARACTERISTICS

The AC specifications are a function of the particular process used to manufacture the part, the
ratings of the I/O buffers, the capacitive load, and the internal routing capacitance. Most of the
specifications can be expressed in terms of multiple input clock periods (T
usually experience less than a ±20 nS variation. The numbers below represent the performance
expected from a 0.8 micron CMOS process when using 2 and 4 mA output buffers.

Publication Release Date: December 1997

- 13 - Revision A2

CP), and actual parts will

Clock Input Waveform

W78C54

XTAL1

T

CH

F

Continued

OP,

T

CL

T

CP

PARAMETER SYMBOL MIN. TYP. MAX. UNIT NOTES

Operating Speed FOP 0 - 40 MHz 1

Clock Period TCP 25 - - nS 2

Clock High TCH 10 - - nS 3

Clock Low TCL 10 - - nS 3

Notes:

1. The clock may be stopped indefinitely in either state.

2. The T

CP specification is used as a reference in other specifications.

3. There are no duty cycle requirements on the XTAL1 input.

Program Fetch Cycle

External Program Memory Fetch Cycle (see Figure 6)

PARAMETER SYMBOL MIN. TYP. MAX. UINT NOTES

Address Valid to ALE Low TAAS

Address Hold After ALE Low TAAH

T

ALE Low to PSEN Low

PSEN Low to Data Valid

Data Hold After PSEN High

Data Float After PSEN High

APL

PDA --2TCP nS 2

T

PDH 0-1TCP nS 3

T

PDZ 0-1TCP nS

T

ALE Pulse Width TALW

PSW

PSEN Pulse Width

Notes:

1. P00-P07, P20-P27 remain stable through entire memory cycle.

2. Memory access time is 3 Tcp.

3. Data has been latched internally prior to /PSEN going high.

4. ∆ is 20 ns (due to buffer driving delay and wire loading).

T

1TCP -∆

1TCP -∆

1TCP -∆

2TCP -∆

3TCP -∆

--nS

--nS1

CP

1T

2T

3T

CP

CP

1TCP+∆

2TCP +∆

3TCP +∆

nS

nS 4

nS 4

- 14 -

Data Read Cycle

External Data Memory Read Cycle (see Figure 7)

PARAMETER SYMBOL MIN. TYP. MAX. UINT NOTES

T

ALE Low to RD Low

RD Low to Data Valid

Data hold After RD High

Data Float After RD High

RD Pulse Width

Notes:

1. Data Memory access time is 5 Tcp.

2. ∆ is 20 ns (due to buffer driving delay and wire loading.

DAR

T

DDA - - 4 Tcp nS 1

DDH 0 - 2 Tcp nS

T

DDZ 0 - 2 Tcp nS

T

DRD

T

3 Tcp-∆

6 Tcp-∆

Data Write Cycle

External Data Memory Write Cycle (see Figure 8)

PARAMETER SYMBOL MIN. TYP. MAX. UINT NOTE

DAW

ALE Low to WR Low

Data Valid to WR Low

Data hold After WR High

WR Pulse Width

T

T

T

T

DAD

DWD

DWR

3 Tcp-∆

1 Tcp-∆

1 Tcp-∆

6 Tcp-∆

W78C54

3 Tcp

6 Tcp

3 Tcp

3 Tcp+∆

6 Tcp+∆

3 Tcp+∆

--nS

--nS

6 Tcp

6 Tcp+∆

nS 1, 2

nS 2

nS *

nS *

*Note: ∆ is 20 ns (due to buffer driving delay and wire loading)

Port Access Cycle

Port Access Cycle (see Figure 9)

PARAMETER SYMBOL MIN. TYP. MAX. UINT

Port Input Setup to ALE Low TPDS 1Tcp - - nS

Port Input Hold After ALE Low TPDH 0--nS

Port Output to ALE High TPDA

Note: Ports are read during S5P2, and output data becomes available at the end of S6P2. The timing data are referenced to

ALE, since it provides a convenient reference.

1Tcp-∆

Publication Release Date: December 1997

- 15 - Revision A2

--nS