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W78E51B Schematic ( PDF Datasheet ) - Winbond

Teilenummer W78E51B
Beschreibung 8-BIT MTP MICROCONTROLLER
Hersteller Winbond
Logo Winbond Logo 




Gesamt 23 Seiten
W78E51B Datasheet, Funktion
Preliminary W78E51B
8-BIT MTP MICROCONTROLLER
GENERAL DESCRIPTION
The W78E51B is an 8-bit microcontroller which can accommodate a wider frequency range with low
power consumption. The instruction set for the W78E51B is fully compatible with the standard 8051.
The W78E51B contains an 4K bytes MTP ROM (Multiple-Time Programmable ROM); a 128 bytes
RAM; four 8-bit bi-directional and bit-addressable I/O ports; an additional 4-bit I/O port P4; two 16-bit
timer/counters; a hardware watchdog timer and a serial port. These peripherals are supported by
seven sources two-level interrupt capability. To facilitate programming and verification, the MTP-
ROM inside the W78E51B allows the program memory to be programmed and read electronically.
Once the code is confirmed, the user can protect the code for security.
The W78E51B microcontroller has two power reduction modes, idle mode and power-down mode,
both of which are software selectable. The idle mode turns off the processor clock but allows for
continued peripheral operation. The power-down mode stops the crystal oscillator for minimum power
consumption. The external clock can be stopped at any time and in any state without affecting the
processor.
FEATURES
Fully static design 8-bit CMOS microcontroller
Wide supply voltage of 4.5V to 5.5V
128 bytes of on-chip scratchpad RAM
4 KB electrically erasable/programmable MTP-ROM
64 KB program memory address space
64 KB data memory address space
Four 8-bit bi-directional ports
One extra 4-bit bit-addressable I/O port, additional INT2 / INT3
(available on 44-pin PLCC/QFP package)
Two 16-bit timer/counters
One full duplex serial port(UART)
Watchdog Timer
seven sources, two-level interrupt capability
EMI reduction mode
Built-in power management
Code protection mechanism
Packages:
DIP 40: W78E51B-24/40
PLCC 44: W78E51BP-24/40
PQFP 44: W78E51BF-24/40
Publication Release Date: December 1998
- 1 - Revision A1






W78E51B Datasheet, Funktion
Preliminary W78E51B
3. Reduce EMI Emission
Because of on-chip MTP-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. The
AO bit in the AUXR register, when set, disables the ALE output. In order to reduce EMI emission from
oscillation circuitry, W78E51B allows user to diminish the gain of on-chip oscillator amplifiers by using
programmer to clear the B7 bit of security register. Once B7 is set to 0, a half of gain will be
decreased. Care must be taken if user attempts to diminish the gain of oscillator amplifier, reducing a
half of gain may effect to external crystal operating improperly at high frequency above 24MHz. The
value of R and C1,C2 may need adjustment while running at lower gain.
***AUXR - Auxiliary register (8EH)
- - - - - - - AO
AO: Turn off ALE output.
4. Power-off Flag
***PCON - Power control (87H)
-
-
-
POF GF1 GF0
PD
IDL
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 VDD has been applied to the part. It can
be used to determine if a reset is a warm boot or a cold boot if it is subsequently reset by software.
Watchdog Timer
The Watchdog timer is a free-running timer which can be programmed by the user to serve as a
system monitor, a time-base generator or an event timer. It is basically a set of dividers that divide
the system clock. The divider output is selectable and determines the time-out interval. When the
time-out occurs a system reset can also be caused if it is enabled. The main use of the Watchdog
timer is as a system monitor. This is important in real-time control applications. In case of power
glitches or electro-magnetic interference, the processor may begin to execute errant code. If this is
left unchecked the entire system may crash. The watchdog time-out selection will result in different
time-out values depending on the clock speed. The Watchdog timer will de disabled on reset. In
general, software should restart the Watchdog timer to put it into a known state. The control bits that
support the Watchdog timer are discussed below.
-6-

6 Page









W78E51B pdf, datenblatt
Preliminary W78E51B
ABSOLUTE MAXIMUM RATINGS
PARAMETER
DC Power Supply
Input Voltage
Operating Temperature
Storage Temperature
SYMBOL
VDDVSS
VIN
TA
TST
MIN.
-0.3
VSS -0.3
0
-55
MAX.
+7.0
VDD +0.3
70
+150
UNIT
V
V
°C
°C
Note: Exposure to conditions beyond those listed under Absolute Maximum Ratings may adversely affect the life and reliability of the
device.
DC CHARACTERISTICS
VCCVSS = 5V ±10%, TA = 25° C, unless otherwise specified.
PARAMETER
SYMBOL TEST CONDITIONS
Operating Voltage
Operating Current
Idle Current
Power Down Current
Input Current
P1, P2, P3, P4
Logical 1-to-0 Transition
Current P1, P2, P3(*1), P4
Input Current
RST (*2)
Input Leakage Current
P0, EA
Output Low Voltage
P1, P2, P3, P4
Output Low Voltage
ALE, PSEN , P0 (*3)
Output High Voltage
P1, P2, P3, P4
Output High Voltage
ALE, PSEN , P0 (*3)
VDD
IDD
IIDLE
IPWDN
IIN1
ITL
IIN2
ILK
VOL1
VOL2
VOH1
VOH2
No load VDD = 5.5V
Idle mode VDD = 5.5V
Power-down mode
VDD = 5.5V
VDD = 5.5V
VIN = 0V or VDD
VDD = 5.5V
VIN = 2.0V (*1)
VDD = 5.5V
VIN = VDD
VDD = 5.5V
0V < VIN < VDD
VDD = 4.5V
IOL1 = +2 mA
VDD = 4.5V
IOL2 = +4 mA
VDD = 4.5V
IOH1 = -100 µA
VDD = 4.5V
IOH2 = -400 µA
SPECIFICATION
MIN.
MAX.
4.5 5.5
- 20
-6
- 50
-50 +10
-550
-
-10 +300
-10 +10
- 0.45
- 0.45
2.4 -
2.4 -
UNIT
V
mA
mA
µA
µA
µA
µA
µA
V
V
V
V
- 12 -

12 Page





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