TLE2662 Datasheet, PDF (30/40 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
precision measurement techniques (continued)
RL
RF
RI
COUT
+
+
C1
R2
R1
1N4933
1
1OUT
2
1IN –
3
1IN +
4
VCC _–
5
SCOUT
6
SCREF
7
OSC
8
SCIN
To ADC
16
VCC ₊
15
2OUT
14
2IN –
13
2IN +
12
CAP–
11
GND
10
CAP+
9
FB/SD
RF
CIN
+
5V
RI
Restart
R3
ǒ Ǔ ^{| SCOUT |}
+ _* ) R2
R1
SCREF
2
40 mV
1
Shutdown
R4
Where: SCREF = 2.5 V Nominal
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
used together. This is evident, for example, in the dependence of V_{ICR –} and V_OL on V_{CC –}. The impact of
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.
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