Datasheet LT1466L, LT1467L (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | Micropower Dual/Quad Precision Rail-to-Rail Input and Output Op Amps |
| Pages / Page | 12 / 9 — APPLICATIONS INFORMATION. Overdrive Protection. Output. Input Offset … |
| File Format / Size | PDF / 249 Kb |
| Document Language | English |
APPLICATIONS INFORMATION. Overdrive Protection. Output. Input Offset Voltage
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LT1466L/LT1467L
U U W U APPLICATIONS INFORMATION
I ply and the other at the positive supply. The resulting 1 then flows through Q5 to the current mirror D3-Q6, furnishing the tail current for the NPN differential pair common mode rejection ratio of 83dB minimum is much Q3-Q4. The switchover point between stages occurs when better than typical rail-to-rail amplifiers. VCM is equal to the base voltage of Q5, which is biased
Overdrive Protection
approximately 1.3V below the positive supply. The LT1466L/LT1467L contain circuits that prevent the The collector currents of the two input pairs are combined output from reversing polarity when the input voltage in the second stage, consisting of Q7-Q11. Most of the exceeds either supply. For these circuits to work properly, voltage gain in the amplifier is contained in this stage. The the input current should be limited to –10mA when the output of the second stage is buffered and applied to the input is below the negative supply, and 0.5mA when the output devices Q12 and Q13. Capacitors C1 and C2 form input is above the positive supply. If the amplifier is to be local feedback loops around the output devices, lowering severely overdriven, an external resistor should be used to the output impedance at high frequencies. Capacitor CC limit the current. sets the amplifier bandwidth.
Output Input Offset Voltage
The output voltage swing and current sinking capability of Since the amplifier has two input stages, the input offset the LT1466L/LT1467L are affected by input overdrive as voltage changes depending upon which stage is active. shown in the Typical Performance Characteristics. When When the amplifier switches between stages, the offset monitoring voltages within 100mV of either rail, gain voltage may go up, down or remain flat. Both stages of the should be taken to keep the output from clipping. LT1466L/LT1467L are trimmed; one at the negative sup- 9
U U W U APPLICATIONS INFORMATION
I ply and the other at the positive supply. The resulting 1 then flows through Q5 to the current mirror D3-Q6, furnishing the tail current for the NPN differential pair common mode rejection ratio of 83dB minimum is much Q3-Q4. The switchover point between stages occurs when better than typical rail-to-rail amplifiers. VCM is equal to the base voltage of Q5, which is biased
Overdrive Protection
approximately 1.3V below the positive supply. The LT1466L/LT1467L contain circuits that prevent the The collector currents of the two input pairs are combined output from reversing polarity when the input voltage in the second stage, consisting of Q7-Q11. Most of the exceeds either supply. For these circuits to work properly, voltage gain in the amplifier is contained in this stage. The the input current should be limited to –10mA when the output of the second stage is buffered and applied to the input is below the negative supply, and 0.5mA when the output devices Q12 and Q13. Capacitors C1 and C2 form input is above the positive supply. If the amplifier is to be local feedback loops around the output devices, lowering severely overdriven, an external resistor should be used to the output impedance at high frequencies. Capacitor CC limit the current. sets the amplifier bandwidth.
Output Input Offset Voltage
The output voltage swing and current sinking capability of Since the amplifier has two input stages, the input offset the LT1466L/LT1467L are affected by input overdrive as voltage changes depending upon which stage is active. shown in the Typical Performance Characteristics. When When the amplifier switches between stages, the offset monitoring voltages within 100mV of either rail, gain voltage may go up, down or remain flat. Both stages of the should be taken to keep the output from clipping. LT1466L/LT1467L are trimmed; one at the negative sup- 9
