TLE2662

DUAL

µPOWER JFET-INPUT OPERATIONAL AMPLIFIER

WITH SWITCHED-CAPACITOR VOLTAGE CONVERTER

SLOS118B – DECEMBER 1992 – REVISED AUGUST 1994

37

POST OFFICE BOX 655303

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.

1OUT

1IN –

1IN +

VCC –

SCOUT

SCREF

OSC

SCIN

VCC +

2OUT

2IN –

2IN +

CAP –

GND

CAP +

FB/SD

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

+

SCIN

+

R2

R1

SCOUT

100

µF

0.002

µF

+

10

µF

2

µF

+

R2

+ R1

SCREF

2

* 40 mV

) 1

+ R1

1.121 V

) 1

Figure 65. Basic Voltage Inverter/Regulator