Datasheet
SLOS209G − JANUARY 1998 − REVISED FEBRUARY 2004
40
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APPLICATION INFORMATION
shutdown function
Three members of the TLV277x family (TLV2770/3/5) have a shutdown terminal for conserving battery life in
portable applications. When the shutdown terminal is tied low, the supply current is reduced to 0.8 µA/channel,
the amplifier is disabled, and the outputs are placed in a high impedance mode. To enable the amplifier, the
shutdown terminal can either be left floating or pulled high. When the shutdown terminal is left floating, care
needs to be taken to ensure that parasitic leakage current at the shutdown terminal does not inadvertently place
the operational amplifier into shutdown. The shutdown terminal threshold is always referenced to V
DD
/2.
Therefore, when operating the device with split supply voltages (e.g. ±2.5 V), the shutdown terminal needs to
be pulled to V
DD
− (not GND) to disable the operational amplifier.
The amplifier’s output with a shutdown pulse is shown in Figures 48, 49, and 50. The amplifier is powered with
a single 5-V supply and configured as a noninverting configuration with a gain of 5. The amplifier turnon and
turnoff times are measured from the 50% point of the shutdown pulse to the 50% point of the output waveform.
The times for the single, dual, and quad are listed in the data tables. The bump on the rising edge of the TLV2770
output waveform is due to the start-up circuit on the bias generator. For the dual and quad (TLV2773/5), this
bump is attributed to the bias generator’s start-up circuit as well as the crosstalk between the other channel(s),
which are in shutdown.
Figures 55 and 56 show the amplifier’s forward and reverse isolation in shutdown. The operational amplifier is
powered by ±1.35-V supplies and configured as a voltage follower (A
V
= 1). The isolation performance is plotted
across frequency for both 0.1 V
PP
and 2.7 V
PP
input signals. During normal operation, the amplifier would not
be able to handle a 2.7-V
PP
input signal with a supply voltage of ±1.35 V since it exceeds the common-mode
input voltage range (V
ICR
). However, this curve illustrates that the amplifier remains in shutdown even under
a worst case scenario.