TS12011 TOUCHSTONE [Touchstone Semiconductor Inc], TS12011 Datasheet - Page 7

• Manufacturer Part Number: TS12011
• Description: A 0.8V/1.5uA Nanopower Op Amp, Comparator, and Reference
• Manufacturer: TOUCHSTONE [Touchstone Semiconductor Inc]

input offset current are less than 20nA and 2nA,
respectively.
Comparator
The TS12011 and TS12012 analog comparator input
stage is robust as it can tolerate input voltages
300mV beyond the power supply rails. To insure
clean
comparator features ±7.5mV internal hysteresis. The
TS12011 push-pull output driver was designed to
minimize supply-current surges while driving ±100µA
loads with an output swing to within 100mV of the
supply rails. The open drain output stage TS12012
can be connected to supply voltages above V
absolute maximum of 5.5V above V
OR logic connections are needed, the open-drain
output stage makes it easy to use this analog
comparator.
0.5mA and 1.4mA of current, respectively. The
TS12011 can source 0.1mA of current.
Reference
The TS12011 and TS12012 on-board 0.58V ±4.5%
reference voltage can source and sink 0.1µA and
APPLICATIONS INFORMATION
Comparator 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
stabilizing analog comparator behavior and requires
external components. As shown in Figure 1, adding
comparator hysteresis creates two trip points: V
(for the rising input voltage) and V
input voltage). The hysteresis band (V
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
out of the region where oscillation occurs. Figure 1
illustrates the case in which an IN- input is a fixed
voltage and an IN+ is varied. If the input signals were
reversed, the figure would be the same with an
inverted output. To save cost and external pcb area,
an internal ±7.5mV hysteresis circuit was added to
the TS12011 and TS12012.
TS12011_12DS r1p0
output
The TS12011 and the TS12012 can sink
is
a
switching
well-established
behavior,
THF
SS
. Where wired-
(for the falling
technique
HB
the
) is defined
DD
analog
to an
THR
to
0.1µA of current and can drive a capacitive load less
than 50pF and greater than 50nF with a maximum
capacitive load of 250nF. The higher the capacitive
load, the lower the noise on the reference voltage
and the longer the time needed for the reference
voltage to respond and become available on the
REFOUT pin. With a 250nF capacitive load, the
reference voltage will settle to within specifications in
approximately 20ms.
Op-Amp Stability
The TS12011 and TS12012 op-amp is able to drive
up to 50pF of capacitive load and still maintain
stability in a unity-gain configuration with a 15kHz
GBWP and a phase margin of 70 degrees with a
100kΩ//20pF
Though the TS12011 and TS12012 address low
frequency applications, it is essential to perform good
layout techniques in order to minimize board leakage
and stray capacitance, which is of a concern in low
power, high impedance circuits. For instance, a
10MΩ resistor coupled with a 1pF stray capacitance
can lead to a pole at approximately 15kHz, which is
the GBWP of the device. If stray capacitance is
unavoidable, a feedback capacitor can be placed in
parallel with the feedback resistor.
Adding Hysteresis to the TS12011 Push-pull
Output Option
Additional hysteresis can be generated with three
external resistors using positive feedback as shown
in Figure 2. Unfortunately, this method also reduces
the hysteresis response time. The procedure to
calculate the resistor values for the TS12011 is as
follows:
Figure 1. TS12011/TS12012 Threshold
Hyesteresis Band
TS12011/TS12012
output load.
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