Datasheet TC7652 (Microchip) - 8

TC7652 4.6 Pin Compatibility FIGURE 4-3: INVERTING AMPLIFIER WITH OPTIONAL CLAMP
Where possible, the 8-pin device pinout conforms to such industry standards as the LM101 and LM741. Null storing external capacitors connect to Pins 1 and 8, R2 which are usually for offset null or compensation capac- itors. Output clamp (Pin 5) is similarly used. For OP05 Clamp and OP07 devices, replacement of the offset null R1
TC7652
– potentiometer (connected between Pins 1 and 8 and Input Output VDD by two capacitors from those pins to VSS) provides + compatibility. Replacing the compensation capacitor between Pins 1 and 8 by two capacitors to VSS is required. The same operation (with the removal of any 0.1µF 0.1µF connection to Pin 5) works for LM101, A748 and sim- ilar parts. Because NC pins provide guarding between input and other pins, the 14-pin device pinout conforms closely to
FIGURE 4-4: USING 741 TO BOOST
the LM108. Because this device does not use any extra
OUTPUT DRIVE
pins and does not provide offset nulling (but requires a
CAPABILITY
compensation capacitor), some layout changes are necessary to convert to the TC7652.
TC7652
-7.5V
4.7 Some Applications
+15V + Figures 4-2 and 4-3 show basic inverting and nonin- + In 741 verting amplifier circuits using the output clamping cir- – Out cuit to enhance overload recovery performance. The – -7.5V only limitations on replacing other op amps with the -15V TC7652 are supply voltage (±8V maximum) and output 0.1 0.1 µF µF drive capability (10k load for full swing). Overcome 10kΩ these limitations with a booster circuit (Figure 4-4) to combine output capabilities of the LM741 (or other Figure 4-5 shows the clamp circuit of a zero offset com- standard device) with input capabilities of the TC7652. parator. Because the clamp circuit requires the invert- These two form a composite device, therefore, when ing input to follow the input signal, problems with a adding the feedback network, the monitor loop gains chopper stabilized op amp are avoided. The threshold stability. input must tolerate the output clamp current VIN/R without disrupting other parts of the system.
FIGURE 4-2: NONINVERTING AMPLIFIER WITH
Figure 4-6 shows how the TC7652 can offset null high
OPTIONAL CLAMP
slew rate and wideband amplifiers. Mixing the TC7652 with circuits operating at ±15V requires a lower supply voltage divider with the TC7660 0.1µF 0.1µF voltage converter circuit operated "backwards." Figure
TC7652
Input + 4-7 shows an approximate connection. Output –
FIGURE 4-5: LOW OFFSET
Clamp R2
COMPARATOR
R3 R 0.1µF 0.1µF 1
TC7652
V + IN VOUT – Clamp VTH 200kΩ to 2mΩ DS21464C-page 8  2001-2012 Microchip Technology Inc. Document Outline 1.0 Electrical Characteristics 2.0 pin descriptions TABLE 2-1: pin function table 3.0 detailed description 3.1 Capacitor Connection 3.2 Output Clamp 3.3 Clock Figure 3-1: TEST CIRCUIT 4.0 TYPICAL APPLICATIONS 4.1 Component Selection 4.2 Static Protection 4.3 Output Stage/Load Driving Figure 4-1: CONNECTION OF INPUT GUARDS 4.4 Thermoelectric Effects 4.5 Guarding 4.6 Pin Compatibility 4.7 Some Applications Figure 4-2: Noninverting amplifier with optional clamp Figure 4-3: inverting amplifier with optional clamp Figure 4-4: using 741 to boost output drive capability Figure 4-5: low offset comparator Figure 4-6: 1437 offset nulled by tc7652 Figure 4-7: splitting +15v with the 7660 at >95% efficiency 5.0 typical characteristics 6.0 packaging information 6.1 Package Marking Information 6.2 Package Dimensions 7.0 Revision History Corporate Office Atlanta Boston Chicago Cleveland Fax: 216-447-0643 Dallas Detroit Indianapolis Toronto Fax: 852-2401-3431 Australia - Sydney China - Beijing China - Shanghai India - Bangalore Korea - Daegu Korea - Seoul Singapore Taiwan - Taipei Fax: 43-7242-2244-393 Denmark - Copenhagen France - Paris Germany - Munich Italy - Milan Spain - Madrid UK - Wokingham Worldwide Sales and Service