TS9001
Output Stage Circuitry
Many conventional analog comparators can draw
orders of magnitude higher supply current when
switching. Because of this behavior, additional
power supply bypass capacitance may be required
to provide additional charge storage during
switching. The design of the TS9001-1’s rail-to-rail
output stage implements a technique that virtually
eliminates supply-current surges when output
transitions occur. The supply-current change as a
function of output transition frequency exhibited by
these analog comparators is very small. Material
benefits of this attribute to battery-power
applications are the increase in operating time and
in reducing the size of power-supply filter capacitors.
Figure 1: TS9001’s Internal VREF Output
Equivalent Circuit
Internal Voltage Reference
The TS9001-1/2’s internal +1.252V voltage
reference exhibits a typical temperature coefficient
of 40ppm/°C over the full -40°C to +85°C
temperature range. An equivalent circuit for the
reference section is illustrated in Figure 1. Since the
output impedance of the voltage reference Is
typically 200kꢀ, its output can be bypassed with a
low-leakage capacitor and is stable for any
capacitive load.
An external buffer – such as the TS1001 – can be
used to buffer the voltage reference output for higher
output current drive or to reduce reference output
impedance.
APPLICATIONS INFORMATION
Low-Voltage, Low-Power Operation
especially when the applied differential input voltage
approaches 0V (zero volt). Externally-introduced
Because they were designed specifically for low-
power, battery-operated applications, the TS9001-
1/2 comparators are an excellent choice. Under
nominal conditions, approximate operating times for
this analog comparator family is illustrated in Table 1
hysteresis is
a
well-established technique to
stabilizing analog comparator behavior and requires
external components. As shown in Figure 2, 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
for
a
number of battery types and their
corresponding charge capacities.
Internal Hysteresis
As a result of circuit noise or unintended parasitic
feedback, many analog comparators often break into
oscillation within their linear region of operation
Table 1: Battery Applications using the TS9001
TS9001/TSM9003
CAPACITY, AA
SIZE (mA-h)
VFRESH
(V)
BATTERY TYPE
RECHARGEABLE
VEND-OF-LIFE (V)
OPERATING TIME
(hrs)
Alkaline (2 Cells)
Nickel-Cadmium (2 Cells)
Lithium-Ion (1 Cell)
No
Yes
Yes
3.0
2.4
3.5
1.8
1.8
2.7
2000
750
2.5 x 106
937,500
1000
1.25 x 106
Nickel-Metal- Hydride
(2 Cells)
Yes
2.4
1.8
1000
1.25 x 106
TS9001DS r1p0
Page 5
RTFDS
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