ZHCS020J January 2011 – March 2021 OPA2835 , OPA835
PRODUCTION DATA
The OPA835 and OPA2835 devices include a power-down mode. Under logic control, the amplifiers can switch from normal operation to a standby current of < 1.5 µA. When the PD pin is connected high, the amplifier is active. Connecting PD pin low disables the amplifier and places the output in a high-impedance state. When the amplifier is configured as a unity-gain buffer, the output stage is in a high dc-impedance state. To protect the input stage of the amplifier, the devices use internal, back-to-back ESD diodes between the inverting and noninverting input pins. This configuration creates a parallel low-impedance path from the amplifier output to the noninverting pin when the differential voltage between the pins exceeds a diode voltage drop. When the op amp is configured in other gains, the feedback (RF) and gain (RG) resistor network forms a parallel load.
The PD pin must be actively driven high or low and must not be left floating. If the power-down mode is not used, PD must be tied to the positive supply rail.
PD logic states are TTL with reference to the negative supply rail, VS–. When the op amp is powered from a single-supply and ground, driven from logic devices with similar VDD voltages to the op amp do not require any special consideration. When the op amp is powered from a split supply, with VS– below ground, an open-collector type of interface with a pullup resistor is more appropriate. Pullup resistor values must be lower than 100 kΩ. Additionally, the drive logic must be negated due to the inverting action of an open-collector gate.