TLE2662

DUAL

µPOWER JFET-INPUT OPERATIONAL AMPLIFIER

WITH SWITCHED-CAPACITOR VOLTAGE CONVERTER

SLOS118B – DECEMBER 1992 – REVISED AUGUST 1994

30

POST OFFICE BOX 655303

APPLICATION INFORMATION

precision measurement techniques (continued)

Restart

RL

RF

RI

To ADC

5 V

RF

RI

+

+

1

2

3

4

5

6

7

8

1OUT

1IN –

1IN +

VCC –

SCOUT

SCREF

OSC

SCIN

16

15

14

13

12

11

10

9

VCC +

2OUT

2IN –

2IN +

CAP–

GND

CAP+

FB/SD

CIN

R2

R1

COUT

C1

Shutdown

R3

R4

Where: SCREF = 2.5 V Nominal

1N4933

+

R2

+ R1

SCREF

2

* 40 mV

) 1

Figure 58. Voltage Inverter With Regulated Output

The reference voltage, though being used as part of the regulation circuitry, is still available for other uses if total

current drawn from it is limited to under 60

µA. The shutdown feature also remains available, though a restart

pulse may be necessary to start the switched-capacitor if the voltage on COUT is not fully discharged. This

restart pulse is isolated from the feedback loop using a blocking diode in the regulation section.

The circuit designer should be aware that the TLE2662 amplifier and switched-capacitor sections are tested

and specified separately. Performance may differ from that shown in the typical characteristics section when

supplying the amplifier negative rail using the switched-capacitor block in each design should be considered

and carefully evaluated.

The more esoteric features of the switched-capacitor building block, including external synchronization of the

internal oscillator and power dissipation considerations, are covered in detail in the following section.