TSM9117 TOUCHSTONE [Touchstone Semiconductor Inc], TSM9117 Datasheet - Page 12

• Manufacturer Part Number: TSM9117
• Description: 1.6V Nanopower Comparators with/without Internal References
• Manufacturer: TOUCHSTONE [Touchstone Semiconductor Inc]

Table 1: Battery Applications using the TSM9117- TSM9120
TSM9117-TSM9120
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
switching. The design of the TSM9117–TSM9120’s
rail-to-rail output stage implements a technique that
virtually eliminates supply-current surges when
output transitions occur. As shown on Page 5 of the
Typical Operating Characteristics, the supply-current
change as a function of output transition frequency
exhibited by this analog comparator family is very
small. Material benefits of this attribute to battery-
power applications is the increase in operating time
and in reducing the size of power-supply filter
capacitors.
TSM9117/9118’s Internal +1.252V V
The TSM9117 and the TSM9118’s internal +1.252V
voltage reference exhibits a typical temperature
coefficient of 100ppm/°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
APPLICATIONS INFORMATION
Low-Voltage, Low-Power Operation
Designed specifically for low-power applications, the
TSM9117–TSM9120 comparators are an excellent
choice. Under nominal conditions, approximate
operating times for this analog comparator family is
illustrated in Table 1 for a number of battery types
and their charge capacities.
Internal Hysteresis
As a result of circuit noise or unintended parasitic
Page 12
Lithium-Ion (1 Cell)
BATTERY TYPE
Alkaline (2 Cells)
Hydride (2 Cells)
Nickel-Cadmium
Nickel-Metal-
provide
(2 Cells)
additional
RECHARGEABLE
Yes
Yes
Yes
No
charge
storage
REF
V
FRESH
(V)
3.0
2.4
3.5
2.4
during
V
END-OF-LIFE
1.8
1.8
2.7
1.8
(V)
CAPACITY, AA
voltage reference is typically 200kΩ, preventing the
reference from driving large loads. The reference is
typically 200kΩ, 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.
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 2, 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,
SIZE (mA-h)
Figure 1: TSM9117 & TSM9118 Internal V
Output Equivalent Circuit
2000
1000
1000
750
is
a
TSM9117/TSM9118
OPERATING TIME
well-established
1.25 x 10
1.25 x 10
2.5 x 10
937,500
(hrs)
6
6
6
TSM9117_20DS r1p0
THF
TSM9119/TSM9120
OPERATING TIME
technique
(for the falling
HB
1.875 x 10
2.5 x 10
2.5 x 10
) is defined
5 x 10
(hrs)
REF
6
RTFDS
6
6
6
THR
to