5 Recent Development in High-Voltage CSA

The INA193-INA198 family of high-voltage current sensors has been very successful, providing customers with high-voltage current sensing and OCP for over a decade. As discussed in Section 4, these devices have limitations in terms of precision and transient performance due to the two-stage setup, especially at near-zero V_sense and in the transition range of common-mode input voltage where both op amps are active.

The INA293 family of devices are designed specifically to solve this issue, as well as to improve performance on all key electrical parameters. The INA293 is the latest ultra-precise high-voltage current sense amplifier with common-mode range from –4 V to 110 V (−20 V to +120 V survival).

The INA293 uses a two-stage topology as shown in Figure 5-1. In the front is a current feedback amplifier powered by drawing a fixed amount of current from the common-mode source attached to the inputs. This effectively creates a floating power supply for the first stage amplifier that is independent of device power supply.

The INA293 output stage is a voltage feedback amplifier that accomplishes differential to single-ended conversion. This two stage structure allows for high bandwidth. V_bias is used as ground reference for the front stage and the inputs of output stage looking into common-mode outputs on R_L. A negative charge pump is used to create V_bias to accommodate input common-mode voltages below ground.

The INA310 is based on the INA293, and incorporates an open-drain comparator with internal reference voltage. Similar to the INA200-INA208, the INA310 comparator can be configured in either transparent or latch mode. The trip point is set with an external resistor divider. One major improvement of INA310 over INA200-INA208 is there is no longer the near-zero V_sense limitation.