MB4214 Datasheet, PDF (4/12 Pages) Fujitsu Component Limited. – TIMER

MB4214
s FUNCTIONAL DESCRIPTIONS
The MB4214 contains reference voltage circuit, oscillator, divider and comparator as shown in Fig. 1. Oscillator frequency is
arbitrary controlled by external resistor RT, capacitor CT and VS input voltage.
Divider consists of 13 stages of divider circuit which is constructed by IIL (Intergrated Injection Logic) technique. It expands the
oscillator period up to 4096times. About 100hours period is achieved by a small capacitor.
Free Running Oscillation (Long period low frequency) is achieved when OSC/FR pin is connected to GND.
START RESISTOR RS
RS is a start resistor which controls zener diode current. Zener current is 20mA max and stability zener voltage 6.2V is generated.
RESET FUNCTION
Counter operation is interrupted by the instruction of reset pin (7pin). All counter is cleared when this pin is connected to GND.
Power on reset is available by connecting a external capacitor CRS. Power on reset time tPOR is formulated:
tPOR = 3.5 ^_C_R_S_ _(s)
IRS
OSCILLATOR PERIOD
Two kinds of oscillator period selecting ways are provided.
Divide internal reference voltage by external resistor, to be the VS voltage.
RT pin voltage and reference voltage has the 2 : 3.5 ratio.
Oscillator period is formulated:
tOSC = ^_3_.5_ RT CT ^___R_2___ (s)
2
R1 + R2
Providing VS voltage in other power supply source.
tOSC
=
K_R__^T_C__T_
2
VS
(s)
Note:
Conversion value K = 1
FREE RUNNING OSCILLATION
Free running oscillation is achieved when OSC/FR pin is connected to GND.
V02 pin outputs 4096times as long as fundamental oscillator frequency.
After the voltage is applied or reset is released, V02 keeps 2048times as long as fundamental period. When OSC/FR pin is left
open, first divider data is output.
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