Datasheet MIC7122 (Microchip) - 7

MIC7122 Micrel capacitance C . The value of C is determined by first V+ IN FB estimating C and then applying the following formula: IN
1
V
⁄2 MIC7122
IN R × C ≤ R × C IN IN FB FB 0V to V+ VOUT 0V to V+ CFB RFB VOUT = VIN RIN V
Figure 4. Voltage Follower/Buffer
IN VOUT VS CIN 0.5V to Q1 VCEO(sus) VOUT 0V to V+ V+ Load
Figure 2. Cancelling Feedback Phase Lag 1
V
⁄2 MIC7122
IN IOUT 0V to 2V Since a significant percentage of C may be caused by board IN Q1 layout, it is important to note that the correct value of C may VCEO = 40V { FB 2N3904 IC(max) = 200mA change when changing from a breadboard to the final circuit R layout. S 10 Change Q1 and R Ω S 1⁄
Typical Circuits
2W for higher current and/or different gain. Some single-supply, rail-to-rail applications for which the V I IN = = 100mA/V as shown OUT MIC7122 is well suited are shown in the circuit diagrams of RS Figures 3 through 7.
Figure 5. Voltage-Controlled Current Sink
V+ R4 V
1⁄2 MIC7122
IN 100k V + C1 VOUT 0V to V+ 0.001µF 0V to V+ AV
1⁄2 MIC7122
R2 VOUT V+ 910k 0V R1 100k R2 R4 V+ 100k 100k R3
Figure 3a. Noninverting Amplifier
100k 100
Figure 6. Square Wave Oscillator
V+ CIN R1 R2 (V) 33k 330k OUT R2 V+ V A = 1+ ≈ 10 V R1
1⁄2 MIC7122
COUT VOUT 0V RL 00 100 V (V) IN R3 V+ R2 330k 330k A = − = = 10 − C1 R4 V
Figure 3b. Noninverting Amplifier Behavior
R1 33k 1µF 330k
Figure 7. AC-Coupled Inverting Amplifier
June 2005 7 MIC7122