U5020M
Pin Description
Pin
1
2
3 to 8
Symbol
Function
TM
Test must not be connected
TM
Test must be connected to GND
Wake-up Wake-up inputs (pull-down
resistor)
There are six digitally debounced
wake-up inputs. During the long
trigger mode each signal slope at
the inputs initiates a reset pulse at
Pin 10.
Ena
Enable output (push-pull)
It is used for the control of periph-
eral components. It is activated
after the processor triggers three
times correctly.
Reset
Reset output (open drain)
Resets the processor in the case of
a trigger error or if a wake-up
pulse occurs during the long
watchdog period.
Trig
Trigger input (pull-up resistor)
It is connected to the microproces-
sor’s trigger signal.
Mode Mode input (pull-up resistor)
The processor’s mode signal initi-
ates the switchover between the
long and the short watchdog time.
V
DD
Supply voltage
GND
Ground, reference voltage
Osc
RC oscillator
t
s
Time switch input
Programming pin to select differ-
ent time durations for the long
watchdog time.
TM
TM
1
2
16 t
s
15 Osc
14 GND
13 V
DD
12 Mode
11 Trig
10 Reset
9
95 10635
9
Wake-up 3
Wake-up
4
10
Wake-up 5
Wake-up 6
Wake-up 7
Wake-up 8
11
12
Ena
13
14
15
16
Figure 2. Pin connections
Functional Description
Supply, Pin 13
The U5020M requires a stabilized supply voltage
5% to comply with its electrical
V
DD
= 5 V
characteristic.
"
+
1t
where t
+
1.35
)
1.57 R
f
1
(C
1
)
0.01)
R
1
in k
W
, C
1
in nF and t in
m
s
The clock frequency determines all time periods of the
logic part as shown in the last section of the data sheet
(timing). With an appropriate selection of components,
the clock frequency, f, is nearly independent of the supply
voltage as shown in figure 3. Frequency tolerance
1%, C
1
= 5%.
D
f
max
= 10% with R
1
An external buffer capacitor of C = 10 nF may be
connected between Pin 13 and GND.
RC-Oscillator, Pin 15
The clock frequency, f, can be adjusted with the
components R
1
and C
1
according to the formula:
"
"
2 (8)
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A3, 27-Feb-97
TEMIC [ TEMIC SEMICONDUCTORS ]
