TA7289F 데이터 시트보기 (PDF) - Toshiba
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TA7289F Datasheet PDF : 19 Pages
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TA7289P/F/FG
Sawtooth OSC circuit consists of Q1 through Q4 and R1 through R3.
R1 and R2 are voltage divider of 5 V build−in regulator.
Q1 is turned “off” when V4 is less than the voltage of 2.5 V + VBE Q4 + VBE Q3 approximately equal to 3.8 V. V4
is increased by C1 charging of I4. Q1 and Q2 are turned “ON” when V4 becomes V4 − H level.
Lower level of V4 (V4 − L) is equal to VBE Q4 + VBE Q3 + VSAT Q1 approximately equal to 1.5 V.
V4 is calculated by following equation.
V4 = 5·(1 − e −
1 ·t) .................................................(1)
C1·R3
Assuming that V4 = 1.5 V (t = t1) and=3.8 V (t = t2).
C1 is external capacitance connected to Pin (4) (or (5)) and R3 is on−chip 20 kΩ resistor.
Therefore, OSC frequency is calculated as follows.
t1 = −C1·R3·1n (1 −
1.5 ) ................................................(2)
5
t2 = −C1·R3·1n (1 −
3.8 ) ................................................(3)
5
fOSC =
1
t1 − t2
=
C1· ( R 3·1n
(1
−
1
1.5 ) −
5
R 3·1n
(1 −
3.8 ))
5
=
1 (kHz) (Unit of C1 is µF)
21.4 C1
ABSOLUTE MAXIMUM RATINGS (Ta = 25°C)
CHARACTERISTIC
Supply Voltage
Reference Voltage
TA7289P
Output Current
TA7289F/FG
TA7289P
TA7289F/FG
Power Dissipation
TA7289P
TA7289F/FG
Operating Temperature
Storage Temperature
Note: NO HEAT SINK
SYMBOL
VCC
Vref
VIN
VI
IO (MAX.)
IO (AVE.)
PD (Note)
Topr
Tstg
RATING
30
30
7
2
1.5
0.8
0.7
0.3
2.3
1.0
−30~85
−55~150
UNIT
V
A
W
°C
°C
5
2006-3-2
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