SLOSE96A january 2023 – july 2023 THS2630
PRODUCTION DATA
Power-down mode is used when power saving is required. The THS2630S power-down (PD) pin is an active low input. If left unconnected, an internal 250‑kΩ resistor to VCC+ keeps the device turned on. The threshold voltage for the power-down function is approximately 1.4 V greater than VCC–. If the PD pin is 1.4 V greater than VCC–, the device is active. If the PD pin is less than 1.4 V greater than VCC–, the device is off. Pull the pin to VCC– to turn the device off. Figure 7-3 shows the simplified version of the power-down circuit. While in the power-down state, the amplifier goes into a high-impedance state. The amplifier output impedance is typically greater than 1 MΩ in the power-down state.
Similar to an op amp in an inverting configuration, the output impedance of an FDA is determined by the feedback network configuration. In addition, the THS2630S has an internal 10‑kΩ resistor at each output that is tied to the VCM error amplifier (see Section 7.2). The differential output impedance is equal to [(2 × RF + 2 × RG) || 20 kΩ]. Figure 7-4 shows the closed-loop output impedance of the THS2630S when in power-down.
VCC = ±5 V, gain = 1 V/V, RF = 1 kΩ, PD = VCC– |