TLE2662 Datasheet, PDF (36/40 Pages) Texas Instruments – DUAL uPOWER JFET-INPUT OPERATIONAL AMPLIFIER WITH SWITCHED-CAPACITOR VOLTAGE CONVERTER

TLE2662
DUAL µPOWER JFET-INPUT OPERATIONAL AMPLIFIER
WITH SWITCHED-CAPACITOR VOLTAGE CONVERTER
SLOS118B – DECEMBER 1992 – REVISED AUGUST 1994
APPLICATION INFORMATION
power dissipation (continued)
+ ń RX VX (4.4 IO)
(7)
[ ƪ ) Ť Ť ƫ where:
VX VCC– (TLE2662 voltage loss) (1.3) VO
and I_OUT = maximum required output current. The factor of 1.3 allows some operating margin for the TLE2662.
When using a 12-V to – 5-V converter at 100-mA output current, calculate the power dissipation without an
external resistor as shown in equation 8.
+ * * ) P (12 V | 5 V | ) (100 mA) (12 V) (100 mA) (0.2)
(8)
+ ) + P 700 mW 240 mW 940 mW
1
COUT
+
2
C1
3
+
SCOUT
4
R2
5
R1
6
7
8
+
SCIN
1OUT
1IN –
1IN +
VCC _–
SCOUT
SCREF
OSC
SCIN
16
VCC +
15
2OUT
14
2IN –
13
2IN +
12
CAP –
11
GND
10
CAP +
9
FB/SD
CIN
+
Rx
Figure 64. Power-Dissipation-Limiting Resistor in Series With CIN
At θ_JA of 130°C/W for a commercial plastic device, a junction temperature rise of 122°C is seen. The device
exceeds the maximum junction temperature at an ambient temperature of 25°C. To calculate the power
dissipation with an external-resistor (R_X), determine how much voltage can be dropped across R_X. The
maximum voltage loss of the TLE2662 in the standard regulator configuration at 100 mA output current is 1.6 V
(see equation 9).
+ * ^ƪ ) ^{Ť Ť ƫ} + VX 12 V (1.6 V) (1.3) –5 V
4.9 V
(9)
and
+ ń + W RX 4.9 V (4.4) (100 mA) 11
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