TLE2662 Datasheet, PDF (37/40 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)
The resistor reduces the power dissipated by the TLE2662 by (4.9 V) (100 mA) = 490 mW. The total power
dissipated by the TLE2662 is equal to (940 mW – 490 mW) = 450 mW. The junction temperature rise is 58°C.
Although commercial devices are functional up to a junction temperature of 125°C, the specifications are tested
to a junction temperature of 100°C. In this example, this means limiting the ambient temperature to 42°C. To
allow higher ambient temperatures, the thermal resistance numbers for the TLE2662 packages represent
worst-case numbers with no heat sinking and still air. Small clip-on heat sinks can be used to lower the thermal
resistance of the TLE2662 package. Airflow in some systems helps to lower the thermal resistance. Wide PC
board traces from the TLE2662 leads helps to remove heat from the device. This is especially true for plastic
packages.
basic voltage inverter
The switched-capacitor block is connected as a basic voltage inverter with regulation as shown in Figure 65.
The magnitude of SCIN must exceed that of the desired SCOUT to accommodate voltage losses due to
switching and regulation. Losses of 1 V to 2 V are typical.
100 µF
+
0.002 µF
+
1
1OUT
2
1IN –
3
1IN +
16
VCC +
15
2OUT
14
2IN –
SCOUT
R2
R1
4
VCC _–
5
SCOUT
6
SCREF
13
2IN +
12
CAP –
11
GND
7
OSC
10
CAP +
SCIN
8
SCIN
9
FB/SD
+
ǒ Ǔ ^{ǒ Ǔ 2µF}
+ R2 R1
| SCOUT |
) _SCREF
* ₂
40 mV
1
+ ) | SCOUT |
R1 _{1.121 V} 1
Figure 65. Basic Voltage Inverter/Regulator
10 µF
+
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37