TS12011 TOUCHSTONE [Touchstone Semiconductor Inc], TS12011 Datasheet - Page 8

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

TS12011/TS12012
Page 8
Figure 2. Using Three Resistors Introduces
Additional Hysteresis in the TS12011
1)
2)
3)
4)
Setting R2. As the leakage current at the IN
pin is less than 20nA, the current through R2
should be at least 150nA to minimize offset
voltage errors caused by the input leakage
current. The current through R2 at the trip
point is (V
one each for the two possible output states:
R2 = V
R2 = (V
From the results of the two formulae, the
smaller of the two resulting resistor values is
chosen. For example, when using the
TS12011 (V
and if I
formulae above produce two resistor values:
3.87MΩ and 12.8MΩ - a 4.02MΩ standard
value for R2 is selected.
Next, the desired hysteresis band (V
set. In this example, V
Resistor R1 is calculated according to the
following equation:
R1 = R2 x (V
and substituting the values selected in 1) and
2) above yields:
R1 = 4.02MΩ x (100mV/2.5V) = 160.8kΩ.
The 160kΩ standard value for R1 is chosen.
The trip point for COMPIN+ rising (V
chosen such that V
R2)/R2 (V
or
In solving for R2, there are two formulas –
REFOUT
DD
R2
REFOUT
- V
THF
= 150nA is chosen, then the
REFOUT
/I
HYSB
REFOUT
R2
is the trip point for V
- V
/V
)/I
= 0.58V) at a V
DD
COMPOUT
R2
)
THR
HYSB
> V
is set to 100mV.
)/R2.
REFOUT
DD
x (R1 +
HYSB
= 2.5V
COMPIN+
THR
) is
) is
5)
6)
falling). This is the threshold voltage at which
the comparator switches its output from low
to high as V
In this example, V
With the V
is then computed as follows:
R3 = 1/[2V/(0.58V x 160kΩ) - (1/160kΩ) -
(1/4.02MΩ)] = 66.43kΩ
value resistor is selected for R3.
The last step is to verify the trip voltages and
hysteresis
resistance values:
For V
V
= 1.93V
For V
V
R3 = 1/[V
In this example, a 69.8kΩ, 1% standard
and Hysteresis Band = V
THR
THF
= V
= V
COMPIN+
COMPIN+
THR
REFOUT
THR
THR
- (R1 x V
COMPIN+
rising:
falling:
/(V
band
from Step 4 above, resistor R3
x R1 [(1/R1) + (1/R2) + (1/R3)]
REFOUT
THR
rises above the trip point.
DD
is set to 2.
using
x R1) - (1/R1) - (1/R2)]
/R2) = 1.83V
TS12011_12DS r1p0
THR
– V
the
THF
= 100mV
standard
RTFDS