TK73200 Ver la hoja de datos (PDF) - Toko America Inc
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TK73200 Datasheet PDF : 12 Pages
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TK73200
APPLICATION INFORMATION
INPUT-OUTPUT CAPACITORS
The output capacitor is necessary for stable operation.
The regulator may oscillate if the output capacitor is too
small or missing. The output capacitor size is determined
by load, transient response and external transistor used.
Evaluation in the circuit is recommended to ensure
performance requirements are satisfied. A minimum of 4.7
µF is necessary for stability, with twice that value
recommended. The minimum recommended input
capacitor is 1 µF. Problems do not occur with larger values
of capacitance. However, extremely low ESR may result
in unstable operation. Thus, the use of large value ceramic
capacitors is not recommended on the output.
EVALUATION BOARD
VOUT
CL
4.7 µF
External
Transistor
1
R2
R1
TK73200
1
RIPK
GND
CON
CN
0.1 µF
CP
0.1 µF
RP
330k
CIN
1 µF
VIN
PULSE CURRENT LIMIT MODE
CP
CN
RP
330 k
VIN
CIN
RIPK
TK73200
VCONT
EMITTER
BASE
R1
EXTERNAL
TRANSISTOR
R2
COLLECTOR
GND
CL
VOUT
The equation for the pulse output current limit is as follows:
ISET (mA) = 90 (mV) / RIPK (Ω)
VOUT
IOUT
SOT23L-8 BOARD LAYOUT
VOUT
During the initial turn-on, charge (surge) current flows to
the output capacitor. This IC has a possibility for the
current limit to operate and to turn off the output by the
charge current of the output capacitor. Therefore, the
relationship between CL and CP is set as shown in the
graph below:
1000
GND
CON
VIN
June 1999 TOKO, Inc.
100
10
STABLE REGION
1
0.01
0.1
1
CP (µF)
10
Page 9
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