Standard ICs
CR timer
BA225 / BA225F / BA235 / BA226 / BA226F / BA236
The BA225, BA225F, BA235, BA226, BA226F, and BA236 are monolithic ICs having independent monostable multi-
vibrator circuits which consume very low current (0.75mA typ.). Using external resistors and capacitors, the timing
control time can be set within a range from 0.01ms to 100ms.
As the BA225, BA225F, and BA235 are triggered at the rising edge of the signal, they have no trigger input differenti-
ating circuit and can be used in measuring instruments, control devices, digital data systems and other equipment as
sub-compact attachments. The BA226, BA226F, and BA236 are available as falling edge trigger types.
•
Applications
Delay timers
Monostable multivibrator (ideal for VCR system con-
trollers)
Pulse generators
•
Features are edge trigger types (BA225 / BA235: ris-
1) As these
ing edge trigger types, BA226 / BA236: falling edge
trigger types), there is no need for an input differenti-
ating circuit.
2) The dual type design enables delay timer configura-
tion.
3) Fewer attachments are required.
4) Current dissipation is as low as 0.75mA for each cir-
cuit.
5) Uniformity in the supply current between high and
low output states simplifies the design of the power
supply section.
6) Wide operating power supply voltage range of 4.0V
to 16V.
7) The BA235 and BA236 pin assignments are sym-
metrical, allowing reverse insertion.
8) Hysteresis in the input results in a high level of noise
withstand resistance.
•
Block diagram
BA225 / BA225F
BA226 / BA226F
BA235 / BA236
OUT1
1
O
8
V
CC
CR1
2
CR
O
T
7
OUT2
O
CR
V
CC
T
GND
T
CR
O
TRIGGER1
3
CR
T
6
CR2
V
CC
1
2
OUT1
3
CR1
4
TRIGGER1
5
GND
6
TRIGGER2
7
CR2
8
OUT2
9
V
CC
GND
4
5
TRIGGER2
V
CC
1
Standard ICs
BA225 / BA225F / BA235 / BA226 / BA226F / BA236
•
Absolute maximum ratings (Ta = 25°C)
Parameter
Power supply voltage
BA225 / BA226
Power
dissipation
BA235 / BA236
BA225F / BA226F
Operating temperature
Storage temperature
Topr
Tstg
Pd
Symbol
V
CC
Limits
16
800
∗
1
950
∗
2
450
∗
3
– 20 ~ + 75
– 55 ~ + 125
Unit
V
mW
mW
mW
°C
°C
∗
1 Reduced by 8mW for each increase in Ta of 1°C over 25°C.
∗
2 Reduced by 9.5mW for each increase in Ta of 1°C over 25°C.
∗
3 Reduced by 4.5mW for each increase in Ta of 1°C over 25°C.
•
Electrical characteristics (unless otherwise noted, Ta = 25°C, V
Parameter
Operating power supply voltage
Quiescent current
Timing accuracy
Timing change with power supply
Timing change with temperature
Trigger voltage
Symbol Min.
V
CC
I
Q
T
ERR
T
DS
T
OT
V
T
4.0
—
—
—
—
1.0
0.7
—
—
3.0
Typ. Max.
5.0
1.5
1
0.5
200
2.0
1.6
70
0.5
4.0
16.0
3.0
10
3.0
—
3.0
2.5
200
1.0
—
CC
= 5V)
Conditions
—
—
R = 100kΩ, C = 0.1µF
∗
1
5V¨16V
—
∗
2
Unit
V
mA
%
%
ppm /
°C
V
µA
V
V
Measurement
circuit
Fig.7
Fig.7
Fig.7
Fig.7
Fig.7
Fig.7
BA236
Trigger current
Output low level voltage
Output high level voltage
I
T
V
OL
V
OH
V
T
= 3.0V (BA225 / BA235)
V
T
= 2.5V (BA226 / BA226F / BA236)
I
SINK
= 5mA
I
SOURCE
= 5mA
Fig.7
Fig.7
Fig.7
∗
1 One-shot cycle T = 0.5 CR
∗
2 With input hysteresis (hysteresis width
200 to 600mV)
•
Electrical characteristic curves
SATURATION VOLTAGE: V
CC
—V
OH
(V)
V
CC
= 5V
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
0
0
4
8
12
16
20
SATURATION VOLTAGE: V
OL
(V)
QUIESCENT CURRENT: I
O
(mA)
4
3
"H" output
2
"L" output
2.0
V
CC
= 5V
1.0
1
0
0
4
8
12
16
20
0
0
4
8
12
16
20
POWER SUPPLY VOLTAGE: V
CC
(V)
SOURCE CURRENT: I
SOURCE
(mA)
SINK CURRENT: I
SINK
(mA)
Fig. 1 Quiescent current vs. power
supply voltage
Fig. 2 Output voltage (logic 1
side) characteristics
Fig. 3 Output voltage (logic 0
side) characteristics
2
Standard ICs
BA225 / BA225F / BA235 / BA226 / BA226F / BA236
C = 0.01µF
R = 100kΩ
DELAY TIME NORMALIZED: td
DELAY TIME NORMALIZED: td
1.020
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980
V
CC
= 5V
C = 0.01µF
R = 100kΩ
CAPACITANCE: C (µF)
10
1.010
1.005
1.000
0.995
0.990
0.985
0.980
0
0
4
8
12
16
20
1.0
10
k
10
Ω
0.1
0k
Ω
0.01
– 25
0
25
50
75
0.001
0.01
0.1
1
10
100
TIMING PERIOD: T (ms)
POWER SUPPLY VOLTAGE: V
CC
(V)
AMBIENT TEMPERATURE: Ta (°C)
Fig. 4 Power supply voltage vs.
delay time
Fig. 5 Temperature vs.
delay time
Fig. 6 One-shot time
characteristics
•
Measurement circuit
S
1
OFF
S
0
mA
ON
V
CC
V
CC
S
2
IN
D.V
µA
PG
BA225
BA225F
BA235
CR
100kΩ
GND
OUT
S
3
Counter
5mA
5mA
D.V
0.1µF
Fig. 7
components
•
Attachedcapacitors (Pins 2 and 6)
(1) Timing
Connected between these pins and the ground (GND),
this capacitor determines the one-shot period. We rec-
ommend using a capacitor with a value greater than
1000pF. The one-shot cycle is determined by T = 1 / 2
C • R.
(2) Timing resistor (Pins 2 and 6)
Connected to the power supply line, these resistors
determine the one-shot period. The timing capacitor is
charged through this resistor. The recommended range
for the timing resistor is 10kΩ to 1MΩ.
(3) Power supply capacitor (Pin 8)
Connect a 0.02µF capacitor between the power supply
pin and the ground (GND) so as to prevent malfunction
resulting from a rise in the impedance of the power
supply line.
(4) Load (Pins 1 and 7)
A load of up to 5mA can be accommodated for both the
inflow current and the outflow current.
1M
Ω
3
Standard ICs
BA225 / BA225F / BA235 / BA226 / BA226F / BA236
•
Operation notesfor voltage
(1) Usage range
The recommended voltage range is 4.0V to 16V. Use
of these ICs at 3.0V or lower voltage may cause the
same mode as the input trigger signal to be output at
around 2.6V.
(2) Input trigger
The input trigger level is 2.0V. The LOW level is 1.0V
or lower and the HIGH level is 3.0 V or higher. Trigger
signals of 10ms / V or lower should be used for both
the rising and falling edges.
(3) Time constant determining C • R
The recommended value for the timing capacitor is
1000pF or more and that for the timing resistor is from
10kΩ to 1MΩ.
The voltage, which is determined by comparison of dis-
charge resistance and the timing resistance in the IC,
remains on the CR pins. If timing resistance is set at
5kΩ or less, this voltage will reach threshold level (0.4
×
V
CC
), and operation will come to a halt. Also, when
timing resistance is set to a low value, voltage remains
on the CR pins, which shortens the time constant. If
timing resistance is set to 2MΩ or higher, the IC's inter-
nal comparator cannot be driven, which may bring
operation to a halt.
(4) Note that pin connections and pin arrangements on
the BA225 / BA226 (BA235F / BA226F) differ from
those on the BA235 / BA236.
•
Application exampleexample of the circuit including
Figure 8 shows an
these ICs, while Figure 9 shows the basic operation
timing chart. Figure 10 shows the basic operation tim-
ing chart of the falling edge trigger type IC. When no
trigger signal is applied, the output is in the LOW state
and the timing capacitor is in the discharged state.
When a trigger signal is applied, its rising edge causes
the output to become HIGH and the timing capacitor to
be charged.
The charging time of this timing capacitor is determined
by the time constants of the external timing resistor and
the timing capacitor. When the charged voltage reach-
es 0.4
×
V
CC
, the flip-flop in the IC is reset and the out-
put state changes from HIGH to LOW. At the same
time, the timing capacitor is discharged to be ready for
the next operation.
0.02µF
V
CC
R
OUT2
100kΩ
0.1µF
C
5
V
CC
= 5V
8
V
CC
7
6
CR
0
M. M2
T
M. M1
0
CR
1
OUT1
100kΩ
R
V
CC
0.1µF
C
2
3
T
BA225
BA226
BA225F
BA226F
GND
4
Fig. 8
4
Standard ICs
BA225 / BA225F / BA235 / BA226 / BA226F / BA236
•
Application examples
Rising edge trigger
Trigger input
0.4V
CC
CR pin
T
Output
One-shot cycle: T
0.5 CR
Fig. 9 Basic operation timing chart
(Rising edge trigger)
Falling edge trigger
Trigger input
0.4V
CC
CR pin
T
Output
One-shot cycle: T
0.5 CR
Fig. 10 Basic operation timing chart
(Falling edge trigger)
5
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