LP2901-Q1_14 Datasheet, PDF (5/10 Pages) Texas Instruments – LOW-POWER QUAD DIFFERENTIAL COMPARATOR

LP2901-Q1
www.ti.com................................................................................................................................................ SLCS148A – SEPTEMBER 2005 – REVISED APRIL 2008
Without transistor Q3, if the output voltage were allowed to drop below 0.8 V, transistor Q1 would saturate, and
the output current would drop to zero. The circuit would be unable to pull low current loads down to ground or the
negative supply, if used. Transistor Q3 has been included to bypass transistor Q1 under these conditions and
apply the current I₁ directly to the base of Q2. The output sink current now is approximately I₁ times the h_FE of
Q2 (700 µA at V_O = 0.4 V). The output of the devices exhibits a bimodal characteristic, with a smooth transition
between modes.
In both cases, the output is an uncommitted collector. Several outputs can be tied together to provide a dot logic
function. An output pullup resistor can be connected to any available power-supply voltage within the permitted
power-supply range, and there is no restriction on this voltage, based on the magnitude of the voltage that is
supplied to V_CC of the package.
Copyright © 2005–2008, Texas Instruments Incorporated
Product Folder Link(s): LP2901-Q1
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