TC1026CEOA Microchip Technology, TC1026CEOA Datasheet - Page 6

• Manufacturer Part Number: TC1026CEOA
• Description: IC COMPARATOR OPAMP/REF 8SOIC
• Manufacturer: Microchip Technology
• Type: Amplifier, Comparator, Referencer

Specifications of TC1026CEOA

• Package / Case: 8-SOIC (3.9mm Width)
• Applications: General Purpose
• Mounting Type: Surface Mount
• Number Of Channels: 1 Channel
• Output Type: Push-Pull
• Response Time: 4 us
• Offset Voltage (max): 1.5 mV
• Input Bias Current (max): 100 pA
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1.8 V
• Supply Current (max): 18 uA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TC1026
FIGURE 4-1:
4.2
Figure 4-2 is a precision battery low/battery dead
monitoring circuit. Typically, the battery low output
warns the user that a battery dead condition is
imminent. Battery dead typically initiates a forced
shutdown to prevent operation at low internal supply
voltages (which can cause unstable system operation).
The circuit of Figure 4-2 uses two TC1026 devices and
only six external resistors. AMP 1 is a simple buffer
while CMPTR1 and CMPTR2 provide precision voltage
detection using V
R4 set the detection threshold for BATT LOW while
resistors R1and R3 set the detection threshold for
BATT FAIL. The component values shown assert
BATT LOW at 2.2V (typical) and BATT FAIL at 2.0V
(typical). Total current consumed by this circuit is
typically 28µA at 3V. Resistors R5 and R6 provide
hysteresis for comparators CMPTR1 and CMPTR2,
respectively.
DS21725B-page 6
V
SRC
TC1026
Precision Battery Monitor
R
A
R
B
R
as a reference. Resistors R2 and
COMPARATOR
EXTERNAL HYSTERESIS
CONFIGURATION
V
R
V
+
–
DD
TC1026
Comparator
R
C
V
OUT
4.3
The majority of spectral energy for human voices is in
a 2.7kHz frequency band from 300Hz to 3kHz. To
properly recover a voice signal in applications such as
radios, cellular phones and voice pagers, a low-power
bandpass filter that is matched to the human voice
spectrum can be implemented using Microchip’s
CMOS op amps. Figure 4-3 shows a unity-gain multi-
pole Butterworth filter with ripple less than 0.15dB in
the human voice band. The lower 3dB cut-off frequency
is 70Hz (single-order response), while the upper cut-off
frequency is 3.5kHz (fourth-order response).
4.4
Supervisory Audio Tones (SAT) provide a reliable
transmission path between cellular subscriber units
and base stations. The SAT tone functions much like
the current/voltage used in land line telephone systems
to indicate that a phone is off the hook. The SAT tone
may be one of three frequencies: 5970, 6000 or
6030Hz. A loss of SAT implies that channel conditions
are impaired, and if SAT is interrupted for more than 5
seconds, a cellular call is terminated.
Figure 4-4 shows a high Q (30) first order SAT
detection bandpass filter using Microchip’s CMOS op
amp architecture. This circuit nulls all frequencies
except the three SAT tones of interest.
Voice Band Receive Filter
Supervisory Audio Tone (SAT)
Filter for Cellular
©
2002 Microchip Technology Inc.