TS9004
Comparator Output
THEORY OF OPERATION
The TS9004 has a GND pin that allows the output to
swing from V+ to GND while the V- pin can be set to
a voltage below GND as long as the voltage
difference between V+ and V- is within 11V. Having
a different voltage on V- will not affect the output
swing. For TTL applications, V+ can be set to
+5V±10% and V- can be set anywhere between 0V
and -5V±10%. Furthermore, the output design of the
TS9004 can source and sink more than 40mA and
5mA, respectively, while simultaneously maintaining
a quiescent current in the microampere range. If the
power dissipation of the package is maintained
within the max limit, the output can source pulses of
100mA of current with V+ set to +5V. In an effort to
minimize external components needed to address
power supply feedback, the TS9004 output does not
produce crowbar switching current as the output
The TS9004 quad, low-voltage, micropower analog
comparator provides excellent flexibility and
performance while sourcing continuously up to
40mA of current. The TS9004 draws 8µA (max) for
all 4 comparators, including the reference. It exhibits
an input offset voltage of ±4.5mV, and has an
on-board +1.182V ±0.75% voltage reference. To
minimize glitches that can occur with parasitic
feedback or a less than optimal board layout, the
design of the TS9004 output stage is optimized to
eliminate crowbar glitches as the output switches.
Power-Supply and Input Signal Ranges
The TS9004 can operate from a single supply
voltage range of +2.5V to +11V, provides a wide
common mode input voltage range of V- to
V+ - 1.3V, and accept input signals ranging from V-
to V+ - 1V. The inputs can accept an input as much
as 300mV above and below the power supply rails
without damage to the part. While the TS9004 is
able to operate from a single supply voltage range, a
GND pin is available that allows for a dual supply
operation with a range of ±1.25V to ±5.5V. If a single
supply operation is desired, the GND pin needs to
be tied to V-. In a dual supply mode, the TS9004 is
compatible with TTL/CMOS with a ±5V voltage.
switches. With
a
10mV input overdrive, the
propagation delay of the TS9004 is 17μs.
Voltage Reference
The TS9004 has an on-board 1.182V reference
voltage with an accuracy of ±0.75%. The REF pin is
able to source and sink 20μA and 10μA of current,
respectively. The REF pin is referenced to V- and it
should not be bypassed.
Noise Considerations
Low-Voltage Operation: V+ = 1.5V
Noise can play a role in the overall performance of
the TS9004. Despite having a large gain, if the input
voltage is near or equal to the input offset voltage,
the output will randomly switch HIGH and LOW. As a
result, the TS9004 produces a peak-to-peak noise of
about 0.3mVPP while the reference voltage produces
a peak-to-peak noise of about 1mVPP. Furthermore,
it is important to design a layout that minimizes
capacitive coupling from a given output to the
reference pin as crosstalk can add noise and as a
result, degrade performance.
The TS9004 can operate down to a supply voltage
of 2V; however, as the supply voltage reduces, the
TS9004 supply current drops and the performance is
degraded. When the supply voltage drops to 2.2V,
the reference voltage will no longer function;
however, the comparators will function down to a 1V
supply voltage. Furthermore, the input voltage range
is extended to just below 1V the positive supply rail.
For applications with a sub-2.5V power supply, it is
recommended to evaluate the circuit over the entire
power supply range and temperature.
stabilizing analog comparator behavior and requires
external components. As shown in Figure 1, adding
comparator hysteresis creates two trip points: VTHR
(for the rising input voltage) and VTHF (for the falling
input voltage). The hysteresis band (VHB) is defined
as the voltage difference between the two trip points.
When a comparator’s input voltages are equal,
hysteresis effectively forces one comparator input to
move quickly past the other input, moving the input
APPLICATIONS INFORMATION
Hysteresis
As a result of circuit noise or unintended parasitic
feedback, many analog comparators often break into
oscillation within their linear region of operation
especially when the applied differential input voltage
approaches 0V (zero volt). Externally-introduced
hysteresis is
a
well-established technique to
TS9004DS r1p0
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RTFDS
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