TK11220A TOKO [TOKO, Inc], TK11220A Datasheet - Page 31

• Manufacturer Part Number: TK11220A
• Description: VOLTAGE REGULATOR WITH ON/OFF SWITCH
• Manufacturer: TOKO [TOKO, Inc]

5.) In design, take a vertical line from the maximum
6.) Read off the value of P
The maximum operating current is:
January, 1996 TOKO, Inc.
operating temperature (e.g. 75 C) to the derating
curve.
vertical line intersects the derating curve. This is taken
as the maximum power dissipation, D
I
OUT
ON/OFF
SOT-23L Power Dissipation Curve
+
V O
V IN
+
= (D
500
400
300
200
100
0
SOT-89-5 Board Layout
DEFINITION AND EXPLANATION OF TECHNICAL TERMS (CONT.)
SOT-23L Board Layout
0
PD
Unmounted
/(V
IN(MAX)
50
D
GND
against the point at which the
T A (°C)
Mounted as shown
- V
OUT
100
).
PD
ON/OFF
+
V IN
V O
150
.
23
+
1-4-96
Copper pattern should be as large as possible. Power
dissipation is 400 mW for SOT-23L and 800 mV for SOT-
89-5. A low ESR capacitor is recommended. For low
temperature operation, select a capacitor with a low ESR at
the lowest operating temperature to prevent oscillation,
degradation of ripple rejection and increase in noise. The
minimum recommended capacitance is 2.2 F.
INPUT/OUTPUT DECOUPLING CAPACITOR CONSIDER-
ATIONS
Voltage regulators require input and output decoupling
capacitors. The required value of these capacitors vary
with application. Capacitors made by different manufactur-
ers can have different characteristics, particularly with
regard to high frequencies and equivalent resistance (ESR)
over temperature. The type of capacitor is also important.
For example, a 4.7 F aluminum electrolytic may be re-
quired for a certain application. If a tantalum capacitor is
used, a lower value of 2.2 F would be adequate. It is
important to consider the temperature characteristics of the
decoupling capacitors. While Toko regulators are de-
signed to operate as low as -40 C, many capacitors will not
operate properly at this temperature. The capacitance of
aluminum electrolytic capacitors may decrease to 0 at low
temperatures. This may cause oscillation on the output of
the regulator since some capacitance is required to guar-
antee stability. Thus, it is important to consider the charac-
teristics of the capacitor over temperature when selection
decoupling capacitors. The ESR is another important
parameter. The ESR will increase with temperature but low
ESR capacitors are often larger and more costly.
general, Tantalum capacitors offer lower ESR than alumi-
num electrolytic, but new low ESR aluminum electrolytic
SOT-89-5 Power Dissipation Curve
2000
1000
0
0
Unmounted
as shown
Mounted
50
Ceramic Substrate
25 X 30 mm
T A (°C)
Circuit Board
Glass Epoxy
10 X 10 mm
100
TK112xxA
150
24
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