Monolithic op amp with rail-to-rail output swing and low input bias current

Photocoupler

Monolithic op amps have been available since the 1960s, but the widely used devices are steadily improving in performance. The LTC6090 precision monolithic op amp is a big step forward, extending the supply voltage to ±70V without sacrificing the features that high-precision op amps are expected to have. The LTC6090 is available in a small 8-pin SO package and a 16-lead TSSOP package. Both packages feature exposed pads for reduced thermal resistance, eliminating the need for additional heat sinks. A simple interface to the low voltage control line and built-in thermal safety features simplify high voltage analog design tasks.

High voltage and high performance

The expectation for an op amp is its low input bias current, low offset, and low noise. The LTC6090 is no exception. The device uses a MOS input stage design with input bias currents typically 3pA (at 25°C) and <100 pA (at 85°C). This makes it ideal for high impedance applications such as the photodiode amplifier shown in Figure 1. The low input offset voltage is less than 1.6mV and the noise is 11nV/√Hz (at 10kHz). Enter the common mode range to either 3V or a 134V range of either rail (across a 140V supply).

Figure 1: Extended Dynamic Range 1M Transimpedance Photodiode Amplifier

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