PRECISION SINGLE CELL TIMER
ISSUE 2 - MAY 1998
DEVICE DESCRIPTION
These devices are precision timing circuits for
generation of accurate time delays or
oscillation. Advanced circuit design means that
these devices can operate from a single battery
cell with the minimum of quiescent current.
In monostable mode time delays are
controlled by a single resistor and capacitor
network. In astable mode the frequency and
du t y cy c l e c a n be a c c u r a t e l y an d
independently controlled with two external
resistors and one capacitor.
The threshold and trigger levels are normally
set as a proportion of V
CC
by internal resistors.
These levels can be programmed by the use
of the control input pin.
When the trigger input reduces to a value
below the trigger level, the flip-flop is set and
the output goes high. With the trigger input
above the trigger level and the threshold input
above the threshold level, the flip-flop is reset
ZSCT1555
and the output goes low. The reset pin has
priority over all the other inputs and is used
to start new timing cycles. A low on the reset
input causes the flip-flop to reset forcing the
output low. Whenever the output is forced
low then the internal discharge transistor is
turned on.
FEATURES
•
•
•
•
•
•
•
0.9V supply operating voltage guaranteed
Pin connections comparable with 555
series timers
Very low quiescent current 74
µA
SO8 and DIL8 packages
Operating temperature range
compatible with battery technologies
APPLICATIONS
Portable and battery powered
equipment
Low voltage and low power systems
SCHEMATIC DIAGRAM
8
VCC
CONTROL
5
6
THRESH
2
TRIGGER
7
DISCHARGE
3
OUTPUT
4
RESET
1
GND
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ZSCT1555
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
Input Voltages
(Cont, Reset, Thres, Trig)
Output Current
Operating Temperature
Storage Temperature
9V
9V
100mA
-20 to 100°C
-55 to 150°C
Power Dissipation (T
amb
=25°C)
DIL8
625mW
SO8
625mW
Recommended Operating Conditions
Supply Voltage
0.9V(min) 6V(max)
Input Voltages
6V(max)
(Cont, Reset, Thres, Trig)
Output Current
Sink
100mA(max)
Source
150µA(max)
ELECTRICAL CHARACTERISTICS
TEST CONDITIONS (Unless otherwise stated):T
amb
=
25°C,V
CC
=
1.5V
SYMBOL PARAMETER
CONDITIONS
MIN.
V
CC
I
CC
V
TH
I
TH
V
TR
I
TR
t
PD
V
RS
I
RS
I
DS
V
DS
V
CT
V
OL
Supply Voltage
Supply Current
Threshold Voltage
V
CC
= 5V
Threshold Current (Note 1)
Trigger Voltage
V
CC
= 5V
Trigger Current
Trigger Propagation delay
Reset Voltage
Reset Current
Discharge switch Off-state
current
Discharge switch On-state
voltage
Control Voltage (Open Circuit)
V
CC
= 5V
Output Voltage (Low)
I
OL
=10mA
I
OL
=50mA
V
CC
=5V, I
OL
=10mA
V
CC
=5V, I
OL
=100mA
Reset @ 0V
Delay from trigger
to output
0.1
0
0
0
I
DS
= 0.2mA
V
CC
= 5V, I
DS
= 0.3mA 0
no load
V
CC
=
5V, no load
0.9
74
150
1.195 1.22
3.9
4
0
0.2
0.57
0
20
0.25
0.62
-35
2
0.2
-5
10
180
240
0.4
-10
100
225
350
LIMITS
TYP.
MAX.
6
120
200
V
mA
UNITS
1.245 V
4.1
100
0.3
0.67
-100
nA
V
nA
µs
V
µA
nA
mV
1.195 1.22
3.9
4
0
0
0
0
0.15
0.45
0.13
0.65
1.1
4.6
1.245 V
4.1
0.3
0.65
0.3
1
1.5
5
V
V
OH
Output Voltage (High)
1
I
OH
= 100µA
V
CC
= 5V, I
OH
= 150µA 4.5
V
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ZSCT1555
ELECTRICAL CHARACTERISTICS (Continued)
TEST CONDITIONS (Unless otherwise stated):T
amb
=25°C,V
CC
=1.5V
SYMBOL PARAMETER
CONDITIONS
MIN.
t
R
t
F
Output pulse rise time
Output pulse fall time
Timing error, Monostable
Initial accuracy (Note 2)
Drift with supply voltage
Drift with temperature
Timing error, Astable
Initial accuracy (Note 2)
Drift with supply voltage
Drift with temperature
Astable maximum frequency
C
L
= 10pF
V
CC
=5V, C
L
=10pF
C
L
= 10pF
V
CC
=5V, C
L
=10pF
RA= 10 to 50 kΩ
RB= 10 to 50 kΩ
C
T
= 68nF
RA= 10 to 50 kΩ
RB= 10 to 50 kΩ
C
T
= 68nF
RA=20 kΩ
RB= 10 kΩ
C
T
=47pF
LIMITS
TYP.
1.6
1.2
240
24
1.6
0.262
100
4.8
0.662
150
330
MAX.
µs
ns
UNITS
∆t
IA
(m)
∆t
V
(m)
∆t
T
(m)
∆t
IA
(a)
∆t
V
(a)
∆t
T
(a)
f
A
%
%/V
ppm/°C
%
%/V
ppm/°C
kHz
Note 1: This will influence the maximum values of RA and RB (RA
MAX
=10MΩ,RB
MAX
=1.5MΩ)
Note 2: Is defined as the difference between the measured value and the average value of a
random sample taken on a batch basis
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ZSCT1555
TYPICAL CHARACTERISTICS
Minimum Pulse Width (µs)
Vcc=1.5v
Rout/Vcc = 1K
Minimum Pulse Width (µs)
5
4
3
2
1
0
0
0.1
+100°C
+25°C
-20°C
5
Vcc=5v
Rout/Vcc = 1K
4
3
2
1
0
0
0.1
0.2
+100°C
+25°C
-20°C
Lowest Voltage Level of Trigger Pulse (xVcc)
Lowest Voltage Level of Trigger Pulse (xVcc)
Minimum Pulse Width Required for
Triggering
5
Vcc=1.5v
Rout/Vcc=1K
+100°C
Minimum Pulse Width Required for
Triggering
8
Vcc=5v
Rout/Vcc=1K
Propagation Delay (µs)
4
3
+25°C
-20°C
Propagation Delay (µs)
6
4
+100°C
+25°C
-20°C
2
1
0
0
2
0
0
0.1
0.2
0.1
0.2
Lowest Voltage Level of Trigger Pulse (xVcc)
Lowest Voltage Level of Trigger Pulse (xVcc)
Output Propagation Delay
200
1.05
Output Propagation Delay
Supply Current (µA)
Pulse Duration
relative to Vcc=5v
160
120
80
40
0
0.0
1.0
2.0
3.0
4.0
5.0
-20°C
+25°C
+100°C
1.00
0.95
0.90
0.85
0.80
0
1
2
3
4
5
6
Supply Voltage (V)
Supply Voltage (V)
Supply Current v Supply Voltage
Normalized Output Pulse Duration
v Supply Voltage
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ZSCT1555
TYPICAL CHARACTERISTICS
1.0
0.8
Vcc=1.5v
0.5
0.4
Vcc=5v
Vcc - Vout (V)
Vcc - Vout (V)
0.6
0.4
0.2
0.0
0.001
-20°C
+25°C
+100°C
0.3
0.2
0.1
0.0
0.001
-20°C
+25°C
+100°C
0.01
0.1
1.0
0.01
0.1
1.0
High-Level Output Current (mA)
High Level Output Current (mA)
Output High Voltage Drop v
Output Current
Low Level Output Voltage (V)
Low Level Output Voltage (V)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.01
Vcc=1.5v
Output High Voltage Drop v
Output Current
1.0
0.8
0.6
0.4
0.2
0.0
0.01
Vcc=5v
-20°C
+25°C
+100°C
-20°C
+25°C
+100°C
0.1
1
10
100
0.1
1
10
100
Low Level Output Current (mA)
Low Level Output Current (mA)
Output Low Voltage Drop v
Output Current
Discharge Transistor Voltage (V)
Discharge Transistor Voltage (V)
10
Vcc=1.5v
Output Low Voltage Drop v
Output Current
10
Vcc=5v
1
-20°C
+25°C
+100°C
1
-20°C
+25°C
+100°C
0.1
0.1
0.001
0.001
0.01
0.1
1
0.01
0.001
0.01
0.1
1
Sink Current (mA)
Sink Current (mA)
Discharge Transistor Voltage
v Sink Current
Discharge Transistor Voltage
v Sink Current
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