TC826CBU [MICROCHIP]
Analog-to-Digital Converter with Bar Graph Display Output; 模拟数字转换器与条形图显示输出
| 型号： | TC826CBU |
| 厂家： | 
MICROCHIP |
| 描述： | Analog-to-Digital Converter with Bar Graph Display Output |
| 文件： | 总18页 (文件大小：473K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TC826
Analog-to-Digital Converter with Bar Graph Display Output
Features
General Description
• Bipolar A/D Conversion
In many applications, a graphical display is preferred
over a digital display. Knowing a process or system
operates, for example, within design limits is more valu-
able than a direct system variable read out. A bar or
moving dot display supplies information precisely with-
out requiring further interpretation by the viewer.
• 2.5% Resolution
• Direct LCD Display Drive
• ‘Thermometer’ BAR or DOT Display
• 40 Data Segments Plus Zero
• Over Range Plus Polarity Indication
• Precision On-Chip Reference: 35ppm/°C
• Differential Analog Input
The TC826 is a complete analog-to-digital converter
with direct liquid crystal (LCD) display drive. The 40
LCD data segments plus zero driver give a 2.5% reso-
lution bar display. Full scale differential input voltage
range extends from 20mV to 2V. The TC826 sensitivity
is 500µV. A low drift 35ppm/°C internal reference, LCD
backplane oscillator and driver, input polarity LCD
driver, and over range LCD driver make designs simple
and low cost. The CMOS design required only 125µA
from a 9V battery. In +5V systems, a TC7660 DC to DC
converter can supply the -5V supply. The differential
analog input leakage is a low 10pA.
• Low Input Leakage: 10pA
• Display Flashes on Over Range
• Display HOLD Mode
• Auto-Zero Cycle Eliminates Zero Adjust
Potentiometer
• 9V Battery Operation
• Low Power Consumption: 1.1mW
• 20mV to 2.0V Full Scale Operation
• Non-Multiplexed LCD Drive for Maximum
Viewing Angle
Two display formats are possible. The BAR mode dis-
play is like a ‘thermometer’ scale. The LCD segment
driver that equals the input, plus all below it are on. The
DOT mode activates only the segment equal to the
input. In either mode, the polarity signal is active for
negative input signals. An over range input signal
causes the display to flash and activates the over range
annunciator. A HOLD mode can be selected that
freezes the display and prevents updating.
Device Selection Table
Part Number
Package
Temperature Range
TC826CBU
64-Pin PQFP
0°C to +70°C
The dual slope integrating conversion method with
auto-zero phase maximizes noise immunity and elimi-
nates zero scale adjustment potentiometers. Zero
scale drift is a low 5µV/°C. Conversion rate is typically
5 per second and is adjustable by a single external
resistor.
A compact, 0.5" square, flat package minimizes PC
board area. The high pin count LSI package makes
multiplexed LCD displays unnecessary. Low cost,
direct drive LCD displays offer the widest viewing angle
and are readily available. A standard display is avail-
able now for TC826 prototyping work.
2002 Microchip Technology Inc.
DS21477B-page 1
TC826
Package Type
64-Pin PQFP
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
NC
1
2
48
47
NC
ANALOG
COMMON
BAR 30
BAR 29
BAR 28
BAR 27
BAR 26
BAR 25
BAR 24
BAR 23
+IN
-IN
46
45
44
43
42
41
40
39
38
37
3
4
REF IN
5
6
C
+
REF
C
-
REF
7
V
DD
TC826CBU
8
V
BUF
9
C
AZ
10
11
BAR 22
BAR 21
BAR 20
BAR 19
BAR 18
BAR 17
BAR 16
V
INT
V
SS
12
13
14
15
OSC1
OSC2
BP
36
35
34
33
BAR 0 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Typical Application
C
INT
R
INT
C
AZ
9
10
11
V
INT
6
V
C
BUF
AZ
C
+
REF
1MΩ
C
61
62
REF
1.0mf
BAR/DOT
HOLD
7
C
-
REF
1MΩ
1MΩ
13
OSC1
R
OSC
TC826
430kΩ
14
15
59
63
12
OSC2
BP
TEST
V
SS
OR
REF ANALOG
IN COMMON -IN +IN BAR 40 POL-
BAR 0-
V
DD
8
5
2
4
3
60
Backplane
R
R
2
1
9V
-IN +IN
41 Segment LCD
Bar Graph
2V
Full Scale
200mV
Full Scale
20mV
Full Scale
Component
–
OR
R
INT
2MΩ
20kΩ
20kΩ
C
0.033mf
1mf
0.033mf
1mf
0.033mf
1mf
INT
C
REF
C
AZ
0.068mf
0.068mf
0.014mf
R + R = 250kΩ
1 2
DS21477B-page 2
2002 Microchip Technology Inc.
TC826
*Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to the device. These
are stress ratings only and functional operation of the device
at these or any other conditions above those indicated in the
operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affect device reliability.
1.0
ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings*
Supply Voltage (V+ to V-)....................................... 15V
Analog Input Voltage (Either Input) (Note 1)... V+ to V-
Power Dissipation (T ≤ 70°C)
A
64-Pin Plastic Flat Package ...............................1.14W
Operating Temperature Range:
Commercial Package (C)........................ 0°C to +70°C
Storage Temperature Range.............. -65°C to +150°C
TC826 ELECTRICAL SPECIFICATIONS
Electrical Characteristics: VS = 9V; ROSC = 430kΩ; TA = 25°C; Full Scale = 20mV, unless otherwise stated.
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
Zero Input
-0
±0
+0
1
Display VIN = 0.0V
Zero Reading Drift
—
0.2
µV/°C
VIN = 0.0V
0°C ≤ TA ≤ +70°C
NL
Linearity Error
-1
-1
—
—
—
0.5
0
+1
+1
—
20
—
Count
Count
µVP-P
pA
Max Deviation from Best Straight Line
R/O
EN
Rollover Error
-VIN = +VIN
VIN = 0V
Noise
60
10
50
ILK
Input Leakage Current
Common Mode Rejection Ratio
VIN = 0V
CMRR
µV/V
VCM = ±1V
VIN = 0V
Scale Factor Temperature Coefficient
—
—
1
—
ppm/°C 0 ≤ TA ≤ 7 +0°C
External Ref. Temperature
Coefficient = 0ppm/°C
VCTC
Analog Common Temperature
Coefficient
35
100
ppm/°C 250kΩ between Common and
V+, 0°C ≤ TA ≤ +70°C
VCOM
VSD
VBD
IDD
Analog Common Voltage
LCD Segment Drive Voltage
LCD Backplane Drive Voltage
Power Supply Current
2.7
4
2.9
5
3.35
6
V
250kΩ between Common and VDD
VP-P
VP-P
µA
4
5
6
—
125
175
Note 1: Input voltages may exceed the supply voltages when the input current is limited to 100µA.
2: Static sensitive device. Unused devices should be stored in conductive material to protect devices from static discharge
and static fields.
3: Backplane drive is in phase with segment drive for ‘off’ segment and 180°C out of phase for ‘on’ segment. Frequency is
10 times conversion rate.
4: Logic input pins 58, 59, and 60 should be connected through 1MΩ series resistors to VSS for logic 0.
2002 Microchip Technology Inc.
DS21477B-page 3
TC826
2.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
PIN FUNCTION TABLE
Pin Number
(64-Pin PQFP)
Symbol
Description
1
2
NC
Positive analog signal input.
ANALOG
COMMON
Establishes the internal analog ground point. Analog common is set to 2.9V below the
positive supply COMMON by an internal zener reference circuit. The voltage difference
between VDD and analog common can be used to supply the TC826 voltage reference
input at REF IN (Pin 5).
3
4
5
+IN
-IN
Positive analog signal input.
Negative analog signal input.
REF IN
Reference voltage positive input. Measured relative to analog common.
REF IN ≈ Full Scale/2.
6
CREF
+
Reference capacitor connection.
Reference capacitor connection.
Positive supply terminal.
7
CREF
VDD
-
8
9
VBUF
CAZ
Buffer output. Integration resistor connection.
Negative comparator input. Auto-zero capacitor connection.
Integrator output. Integration capacitor connection.
Negative supply terminal.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
VINT
VSS
OSC1
OSC2
BP
Oscillator resistor (ROSC) connection.
Oscillator resistor (ROSC) connection.
LCD Backplane driver.
BAR 0
NC
LCD Segment driver: Bar 0.
No connection.
BAR 1
BAR 2
BAR 3
BAR 4
BAR 5
BAR 6
BAR 7
BAR 8
BAR 9
BAR 10
BAR 11
BAR 12
BAR 13
BAR 14
BAR 15
BAR 16
BAR 17
BAR 18
BAR 19
BAR 20
BAR 21
BAR 22
BAR 23
LCD Segment driver: Bar 1.
LCD Segment driver: Bar 2.
LCD Segment driver: Bar 3.
LCD Segment driver: Bar 4.
LCD Segment driver: Bar 5.
LCD Segment driver: Bar 6.
LCD Segment driver: Bar 7.
LCD Segment driver: Bar 8.
LCD Segment driver: Bar 9.
LCD Segment driver: Bar 10.
LCD Segment driver: Bar 11.
LCD Segment driver: Bar 12.
LCD Segment driver: Bar 13.
LCD Segment driver: Bar 14.
LCD Segment driver: Bar 15.
LCD Segment driver: Bar 16.
LCD Segment driver: Bar 17.
LCD Segment driver: Bar 18.
LCD Segment driver: Bar 19.
LCD Segment driver: Bar 20.
LCD Segment driver: Bar 21.
LCD Segment driver: Bar 22.
LCD Segment driver: Bar 23.
DS21477B-page 4
2002 Microchip Technology Inc.
TC826
TABLE 2-1:
PIN FUNCTION TABLE (CONTINUED)
Pin Number
(64-Pin PQFP)
Symbol
Description
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
BAR 24
BAR 25
BAR 26
BAR 27
BAR 28
BAR 29
BAR 30
NC
LCD Segment driver: Bar 24.
LCD Segment driver: Bar 25.
LCD Segment driver: Bar 26.
LCD Segment driver: Bar 27.
LCD Segment driver: Bar 28.
LCD Segment driver: Bar 29.
LCD Segment driver: Bar 30.
No connection.
BAR 31
BAR 32
BAR 33
BAR 34
BAR 35
BAR 36
BAR 37
BAR 38
BAR 39
BAR 40
OR
LCD Segment driver: Bar 31.
LCD Segment driver: Bar 32.
LCD Segment driver: Bar 33.
LCD Segment driver: Bar 34.
LCD Segment driver: Bar 35.
LCD Segment driver: Bar 36.
LCD Segment driver: Bar 37.
LCD Segment driver: Bar 38.
LCD Segment driver: Bar 39.
LCD Segment driver: Bar 40.
LCD segment driver that indicated input out-of-range condition.
LCD segment driver that indicates input signal is negative.
POL-
BAR/DOT
Input logic signal that selects BAR or DOT display format. Normally in BAR mode. Connect
to VSS through 1MΩ resistor for DOT format.
62
63
HOLD
TEST
Input logic signal that prevents display from changing. Pulled high internally to inactive
state. Connect to VSS through 1MΩ series resistor for HOLD mode operation.
Input logic signal. Sets TC826 to BAR Display mode. BAR 0 to 40, plus OR flash on and
off. The POL- LCD driver is on. Pulled high internally to inactive state. Connect to VSS with
1MΩ series resistor to activate.
64
NC
No connection.
2002 Microchip Technology Inc.
DS21477B-page 5
TC826
A simple mathematical equation relates the input signal
reference voltage and integration time:
3.0
3.1
DETAILED DESCRIPTION
Dual Slope Conversion Principles
EQUATION 3-1:
The TC826 is a dual slope, integrating analog-to-digital
converter. The conventional dual slope converter mea-
surement cycle has two distinct phases:
t
V T
1
RC
INT
R
RI
V
(t)dt =
IN
0
RC
• Input Signal Integration
Where:
• Reference Voltage Integration (De-integration)
V
V
= Reference Voltage
R
The input signal being converted is integrated for a
fixed time period (T ). Time is measured by counting
clock pulses. An opposite polarity constant reference
voltage is then integrated until the integrator output
voltage returns to zero. The reference integration time
= Signal Integration Time (Fixed)
SI
RI
SI
T
= Reference Voltage Integration Time
(Variable)
is directly proportional to the input signal (T
(Figure 3-1).
)
RI
In a simple dual slope converter, a complete conver-
sion requires the integrator output to ‘ramp-up’ and
‘ramp-down’.
FIGURE 3-1:
BASIC DUAL SLOPE CONVERTER
C
Integrator
R
Analog Input
Signal
–
Comparator
–
+
+
+/–
Phase Control
REF
Voltage
Switch Driver
Control
Logic
Clock
Polarity Control
Counter
Display
V
V
≈ 1/2 V
IN
FULL SCALE
≈ 1/4 V
IN
FULL SCALE
Fixed Signal
Integrate
Time
Variable
Reference
Integrate
Time
DS21477B-page 6
2002 Microchip Technology Inc.
TC826
For a constant V
:
FIGURE 3-2:
NORMAL MODE
IN
REJECTION OF DUAL
SLOPE CONVERTER
EQUATION 3-2:
T
T
RI
SI
30
V
= V
R
IN
T = Measurement
Period
The dual slope converter accuracy is unrelated to the
integrating resistor and capacitor values, as long as
they are stable during a measurement cycle. An inher-
ent benefit is noise immunity. Noise spikes are inte-
grated or averaged to zero during the integration
periods. Integrating ADCs are immune to the large con-
version errors that plague successive approximation
converters in high noise environments. Interfering sig-
nals with frequency components at multiples of the
averaging period will be attenuated (Figure 3-2).
20
10
0
0.1/T
1/T
10/T
Input Frequency
The TC826 converter improves the conventional dual
slope conversion technique by incorporating an auto-
zero phase. This phase eliminates zero scale offset
errors and drift. A potentiometer is not required to
obtain a zero output for zero input.
2002 Microchip Technology Inc.
DS21477B-page 7
TC826
The auto-zero cycle length is 19 counts minimum.
Unused time in the de-integrate cycle is added to the
auto-zero cycle.
4.0
4.1
THEORY OF OPERATION
Analog Section
In addition to the basic signal integrate and de-
integrate cycles discussed above, the TC826 incorpo-
rates an auto-zero cycle.This cycle removes buffer
amplifier, integrator, and comparator offset voltage
error terms from the conversion. A true digital zero
reading results without external adjusting potentiome-
ters. A complete conversion consists of three cycles:
an auto-zero, signal integrate and reference cycle
(Figure 4-1 and Figure 4-2).
4.1.2
SIGNAL INTEGRATION CYCLE
The auto-zero loop is opened and the internal differen-
tial inputs connect to +IN and -IN. The differential input
signal is integrated for a fixed time period. The TC826
signal integration period is 20 clock periods or counts.
The externally set clock frequency is divided by 32
before clocking the internal counters. The integration
time period is:
EQUATION 4-1:
4.1.1
AUTO-ZERO CYCLE
Where:
During the auto-zero cycle, the differential input signal
is disconnected from the circuit by opening internal
analog gates. The internal nodes are shorted to analog
common (internal analog ground) to establish a zero
input condition. Additional analog gates close a feed-
back loop around the offset voltage error compensation.
32
T
=
x 20
SI
F
OSC
F
= External Clock Frequency
OSC
The voltage level established on C compensates for
AZ
device offset voltages.
FIGURE 4-1:
TC826 ANALOG SECTION
R
INT
REF IN
5
V
DD
8
C
REF
C
C
INT
AZ
6
7
9
10
11
TC826
AZ
Integrator
–
–
+
CMPTR
To Digital Section
+
3
+Input
+
–
Buffer
Comparator
AZ
INT
AZ
DE-
DE+
AZ
INT
V
DD
V
DD
DE+
DE-
2
4
Analog
Common
INT
≈ 6.3V
-INPUT
1µA
≈ V
– 2.9V
DD
From
AZ
–
INT
DE+
DE-
Digital
Control
Center
+
Analog Switch
12
≈ V
DD
DS21477B-page 8
2002 Microchip Technology Inc.
TC826
The differential input voltage must be within the device
Common mode range when the converter and mea-
sured system share the same power supply common
(ground). If the converter and measured system do not
share the same power supply common, -IN should be
tied to analog common. This is the usual connection for
battery operated systems. Polarity is determined at the
end of signal integrate signal phase. The sign bit is a
true polarity indication, in that signals less than 1LSB
are correctly determined. This allows precision null
detection limited only by device noise and system
noise.
4.1.3
REFERENCE INTEGRATE CYCLE
The final phase is reference integrate or de-integrate.
-IN is internally connected to analog common and +IN
is connected with the correct polarity to cause the inte-
grator output to return to zero. The time required for the
output to return to zero is proportional to the input sig-
nal and is between 0 and 40 counts. The digital reading
displayed is:
EQUATION 4-2:
V
IN
20 =
V
REF
FIGURE 4-2:
CONVERSION HAS THREE PHASES
Auto-Zero Phase (AZ)
Signal Integrate
Phase (SI)
Reference Integrate Phase (RI)
(De-integrate)
Sign Bit Determined
Integrator
Output
Analog Common
Potential
True Zero
Crossing
Zero Crossing
Detected
Internal
System
Clock (FSYS)
Internal Data
Latch Update
Signal
Number of Counts
Proportional to
V
IN
T
T ≈ V
D
I
IN
19 Counts
Minimum
20
Counts
41 Counts
Maximum
1
One Conversion Cycle = 80 Counts
(T
= 80 X
)
CONV
FSYS
2002 Microchip Technology Inc.
DS21477B-page 9
TC826
4.2
System Timing
4.4
Components Value Selection
INTEGRATING RESISTOR (R
The oscillator frequency is divided by 32 prior to clock-
ing the internal counters. The three-phase measure-
ment cycle takes a total of 80 clock pulses. The 80
count cycle is independent of input signal magnitude.
4.4.1
)
INT
The desired full scale input voltage and output current
capability of the input buffer and integrator amplifier set
the integration resistor value. The internal class A out-
put stage amplifiers will supply a 1µA drive current with
minimal linearity error. R
1µA full scale current:
Each phase of the measurement cycle has the follow-
ing length:
is easily calculated for a
INT
• Auto-Zero Phase: 19 to 59 Counts
For signals less than full scale, the auto-zero is
assigned the unused reference integrate time period.
EQUATION 4-4:
• Signal Integrate: 20 Counts
This time period is fixed. The integration period is:
V
Full Scale Voltage(V)
1 x 10 – 6
FS
R
=
=
INT
1 x 10 – 6
EQUATION 4-3:
Where V = Full Scale Analog Input
FS
32
T
= 20
SI
F
OSC
4.4.2
INTEGRATING CAPACITOR (C
)
INT
Where F
is the externally set clock frequency.
OSC
The integrating capacitor should be selected to maxi-
mize integrator output swing. The integrator output will
• Reference Integrate: 0 to 41 Counts
swing to within 0.4V of V + or V - without saturating.
S
S
4.3
Reference Voltage Selection
The integrating capacitor is easily calculated:
A full scale reading requires the input signal be twice
the reference voltage. The reference potential is mea-
sured between REF IN (Pin 5) and ANALOG
COMMON (Pin 2).
EQUATION 4-5:
V
640
x V
FS
C
=
INT
F
R
OSC
INT
INT
TABLE 4-1:
Where: V
= Integrator Swing
INT
F
= Oscillator Frequency
OSC
Required Full Scale Voltage
V
REF
20mV
2V
10mV
1V
The integrating capacitor should be selected for low
dielectric absorption to prevent rollover errors. Polypro-
pylene capacitors are suggested.
The internal voltage reference potential available at
analog common will normally be used to supply the
converter’s reference. This potential is stable when-
ever the supply potential is greater than approximately
7V. In applications where an externally generated refer-
ence voltage is desired, refer to Figure 4-3.
4.4.3
AUTO-ZERO CAPACITOR (C
)
AZ
C
should be 2-3 times larger than the integration
AZ
capacitor. A polypropylene capacitor is suggested. Typ-
ical values from 0.14µF to 0.068µF are satisfactory.
The reference voltage is adjusted with a near full scale
input signal. Adjust for proper LCD display read out.
4.4.4
REFERENCE CAPACITOR (C
)
REF
A 1µF capacitor is suggested. Low leakage capacitors,
such as polypropylene, are recommended.
FIGURE 4-3:
EXTERNAL REFERENCE
Several capacitor/resistor combinations for common
full scale input conditions are given in Table 4-2.
V+
8
V+
TC826
MCP1525
5
2
1µF
REF IN
2.50V
Reference
ANALOG
COMMON
(b)
DS21477B-page 10
2002 Microchip Technology Inc.
TC826
TABLE 4-2:
SUGGESTED COMPONENT
VALUES
FIGURE 4-4:
TRANSFER FUNCTION
Over Range
Indication
40
2V
2mV
20mV
Comp.
Full Scale
VREF ≈ 1V
Full Scale
VREF ≈ 100V
Full Scale
VREF ≈ 10V
39
2
RINT
CINT
CREF
CAZ
2MΩ
0.033µF
1µF
200kΩ
0.033µF
1µF
20kΩ
0.033µF
1µF
1
0.068µF
430kΩ
0.068µF
430kΩ
1.14µF
430kΩ
-0.5
0
ROSC
-2
-1
0.5
1
2
3
39 39.5 40 40.5
Note: Approximately 5 conversions/second.
Analog Input
V
40
FS
(X
)
4.5
Differential Signal Inputs
The TC826 is designed with true differential inputs and
accepts input signals within the input stage Common
4.7
BAR/DOT Input (Pin 61)
mode voltage range (V ). The typical range is V+ -1
CM
The BAR/DOT input allows the user to select the dis-
play format. The TC826 powers up in the BAR mode.
Select the DOT display format by connecting BAR/DOT
to the negative supply (Pin 12) through a 1MΩ resistor.
to V- +1V. Common mode voltages are removed from
the system when the TC826 operates from a battery or
floating power source (isolated from measured sys-
tem) and -IN is connected to analog common (V
).
COM
4.8
HOLD Input (Pin 62)
In systems where Common mode rejection ratio mini-
mizes error. Common mode voltages do, however,
affect the integrator output level. Integrator output sat-
uration must be prevented. A worse case condition
The TC826 data output latches are not updated at the
end of each conversion if HOLD is tied to the negative
supply (Pin 12) through a 1MΩ resistor. The LCD dis-
play continuously displays the previous conversion
results.
exists if a large positive V
exists in conjunction with
CM
a full scale negative differential signal. The negative
signal drives the integrator output positive along with
The HOLD pin is normally pulled high by an internal
pull-up.
V
. For such applications, the integrator output swing
CM
can be reduced below the recommended 2V full scale
swing. The integrator output will swing within 0.3V of
V
4.9
TEST Input (Pin 63)
or V without increased linearity error.
DD
SS
The TC826 enters a Test mode with the TEST input
connected to the negative supply (Pin 12). The connec-
tion must be made through a 1MΩ resistor. The TEST
input is normally internally pulled high. A low input sets
the output data latch to all ones. The BAR Display
mode is set. The 41 LCD output segments (zero plus
40 data segments) and over range annunciator flash on
and off at 1/4 the conversion rate. The polarity annun-
ciator (POL-) segment will be on, but not flashing.
4.6
Digital Section
The TC826 contains all the segment drivers necessary
to drive a liquid crystal display (LCD). An LCD back-
plane driver is included. The backplane frequency is
the external clock frequency divided by 256. A 430kΩ
OSC gets the backplane frequency to approximately
55Hz, with a 5V nominal amplitude. When a segment
driver is in phase with the backplane signal, the seg-
ment is ‘OFF’. An out-of-phase segment drive signal
causes the segment to be ‘ON’ or visible. This AC drive
configuration results in negligible DC voltage across
each LCD segment. This insures long LCD display life.
The polarity segment drive, -POL, is ‘ON’ for negative
analog inputs. If +IN and -IN are reversed, this indicator
would reverse. The TC826 transfer function is shown in
Figure 4-4.
4.10 Over Range Display Operation
(OR, Pin 59)
An out-of-range input signal will be indicated on the
LCD display by the OR annunciator driver (Pin 59)
becoming active.
In the BAR display format, the 41 bar segments and the
over range annunciator, OR, will flash ON and OFF. The
flash rate is on fourth the conversion rate (F
/2560).
OSC
In the DOT Display mode, OR flashes and all other data
segment drivers are off.
2002 Microchip Technology Inc.
DS21477B-page 11
TC826
FIGURE 4-6:
EXTERNAL OSCILLATOR
CONNECTION
4.11 Polarity Indication (POL-, Pin 60)
The TC826 converts and displays data for positive and
negative input signals. The POL LCD segment driver
(Pin 60) is active for negative signals.
8
TC826
4.12 Oscillator Operation
9V
12
13
OSC1
14
OSC2
The TC826 external oscillator frequency, F
, is set
OSC
by resistor R
connected between pins 13 and 14.
OSC
The oscillator frequency versus resistance curve is
shown in Figure 4-5.
0.1µf
FIGURE 4-5:
OSCILLATOR
FREQUENCY VS. R
External
Oscillator
OSC
50
40
30
20
10
20
T
= 25°C
18
16
14
12
10
8
A
A. Single 9V Supply
V
to V = 9V
SS
DD
V
= 5V
DD
V
DD
8
Power
Supply
13
TC826
Oscillator
6
0.1µf
4
12
V
SS
2
0
0
2
4
6
OSC
8 10 12 14 16 18 20
(X 100kΩ)
0
B. Dual Supply
V
= 5V
SS
R
4.13 LCD Display Format
F
is divided by 32 to provide an internal system
OSC
The input signal can be displayed in two formats
(Figure 4-7). The BAR/DOT input (Pin 61) selects the
format. The TC826 measurement cycle operates
identically for either mode.
clock, FYSY. Each conversion requires 80 internal
clock cycles. The internal system clock is divided by 8
to provide the LCD backplane drive frequency. The dis-
play flash rate during an input out-of-range signal is set
by dividing FSYS by 320.
FIGURE 4-7:
DISPLAY OPTION
FORMATS
The internal oscillator may be bypassed by driving
OSC1 (Pin 13) with an external signal generator. OSC2
(Pin 14) should be left unconnected.
A. BAR Mode
1. Input = 0
2. Input = 5%
of Full Scale
The oscillator should swing from V
supply operation (Figure 4-6). In dual supply operation,
the signal should swing from power supply ground to
to V in single
SS
DD
Bar 4
Bar 3
Bar 2
Bar 1
Bar 0
Off
Off
Off
Off
On
Off
Off
On
On
On
V
.
DD
B. DOT Mode
1. Input = 0
2. Input = 5%
of Full Scale
Bar 4
Bar 3
Bar 2
Bar 1
Bar 0
Off
Off
Off
Off
On
Off
Off
On
Off
Off
DS21477B-page 12
2002 Microchip Technology Inc.
TC826
4.14 BAR Format
4.17 LCD Backplane Driver (BP, Pin 15)
The TC826 powers up in the BAR mode. BAR/DOT is
pulled high internally. This display format is similar to a
thermometer display. All bars/LCD segments including
zero, below the bar/LCD segment equaling the input
signal level, are on. A half scale input signal, for exam-
ple, would be displayed with BAR 0 to BAR 20 on.
Additional drive electronics are not required to interface
the TC826 to an LCD display. The TC826 has an on-
chip backplane generator and driver. The backplane
frequency is:
FBP = F
/256
OSC
Figure 4-8 gives typical backplane driver rise/fall time
versus backplane capacitance.
4.15 DOT Format
By connecting BAR/DOT to V through a 1MΩ resis-
SS
FIGURE 4-8:
BACKPLANE DRIVE RISE/
FALL TIME VS.
CAPACITANCE
tor, the DOT mode is selected. Only the BAR LCD seg-
ment equaling the input signal is on. The zero segment
is on for zero input.
This mode is useful for moving cursor or ‘needle’ appli-
cations.
10
T
A
= 25°C
= 9V
9
V
S
8
7
6
5
4
3
2
1
4.16 LCD Displays
Most end products will use a custom LCD display for
final production. Custom LCD displays are low cost and
available from all manufacturers. The TC826 interfaces
to non-multiplexed LCD displays. A backplane driver is
included on-chip.
To speed initial evaluation and prototype work, a stan-
dard TC826 LCD display is available from Varitronix.
Varitronix Ltd. LCDs
4/F Liven House
0
1
2
3
4
5
6
7
8
0 10
61-63 King Yip Street
Kwun Tong, Kowloon
Hong Kong
Tel: (852)2389-4317
Fax: (852)2343-9555
Backplane Capacitance (X 100pf)
4.18 Flat Package Socket
Sockets suitable for prototype work are available. A
USA source is:
USA Office:
VL Electronics / Varitronix
3250 Wilshire Blvd., Suite 901
Los Angeles, CA 90010
Tel: (213) 738-8700
Nepenthe Distribution
2471 East Bayshore, Suite 520
Palo Alto, CA 94303
Tel: 415/856-9332
Fax: (213) 738-5340
Telex: 910/373-2060
• Part No.: VBG-413-DP
• ‘BQ’ Socket Part No.: IC51-064-042 BQ
Other standard LCD displays suitable for development
work are available in both linear and circular formats.
One manufacturer is:
UCE Inc.
24 Fitch Street
Norwalk, CT 06855
Tel: 203/838-7509
• Part No. 5040: 50 segment circular display with
3-digit numeric scale.
• Part No. 5020: 50 segment linear display.
2002 Microchip Technology Inc.
DS21477B-page 13
TC826
5.0
5.1
PACKAGING INFORMATION
Package Marking Information
Package marking data not available at this time.
5.2
Taping Form
Component Taping Orientation for 64-Pin PQFP Devices
User Direction of Feed
PIN 1
W
P
Standard Reel Component Orientation
for TR Suffix Device
Carrier Tape, Number of Components Per Reel and Reel Size
Package
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
64-Pin PQFP
32 mm
24 mm
250
13 in
Note: Drawing does not represent total number of pins.
5.3
Package Dimensions
64-Pin PQFP
7° MAX.
.009 (0.23)
.005 (0.13)
.041 (1.03)
.031 (0.78)
PIN 1
.018 (0.45)
.012 (0.30)
.555 (14.10)
.547 (13.90)
.687 (17.45)
.667 (16.95)
.031 (0.80) TYP.
.010 (0.25) TYP.
.555 (14.10)
.547 (13.90)
.120 (3.05)
.100 (2.55)
.687 (17.45)
.667 (16.95)
.130 (3.30) MAX.
Dimensions: mm (inches)
DS21477B-page 14
2002 Microchip Technology Inc.
TC826
NOTES:
2002 Microchip Technology Inc.
DS21477B-page 15
TC826
SALES AND SUPPORT
Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1. Your local Microchip sales office
2. The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277
3. The Microchip Worldwide Site (www.microchip.com)
Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.
New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
DS21477B-page 16
2002 Microchip Technology Inc.
TC826
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical com-
ponents in life support systems is not authorized except with
express written approval by Microchip. No licenses are con-
veyed, implicitly or otherwise, under any intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, FilterLab,
KEELOQ, microID, MPLAB, PIC, PICmicro, PICMASTER,
PICSTART, PRO MATE, SEEVAL and The Embedded Control
Solutions Company are registered trademarks of Microchip Tech-
nology Incorporated in the U.S.A. and other countries.
dsPIC, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,
In-Circuit Serial Programming, ICSP, ICEPIC, microPort,
Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM,
MXDEV, PICC, PICDEM, PICDEM.net, rfPIC, Select Mode
and Total Endurance are trademarks of Microchip Technology
Incorporated in the U.S.A.
Serialized Quick Turn Programming (SQTP) is a service mark
of Microchip Technology Incorporated in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2002, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received QS-9000 quality system
certification for its worldwide headquarters,
design and wafer fabrication facilities in
Chandler and Tempe, Arizona in July 1999
and Mountain View, California in March 2002.
The Company’s quality system processes and
procedures are QS-9000 compliant for its
PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals,
non-volatile memory and analog products. In
addition, Microchip’s quality system for the
design and manufacture of development
systems is ISO 9001 certified.
2002 Microchip Technology Inc.
DS21477B-page 17
WORLDWIDE SALES AND SERVICE
Japan
AMERICAS
ASIA/PACIFIC
Microchip Technology Japan K.K.
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3-18-20, Shinyokohama
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Tel: 81-45-471- 6166 Fax: 81-45-471-6122
Corporate Office
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Technical Support: 480-792-7627
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Tel: 61-2-9868-6733 Fax: 61-2-9868-6755
Korea
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Tel: 480-792-7966 Fax: 480-792-7456
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Co., Ltd., Beijing Liaison Office
Unit 915
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500 Sugar Mill Road, Suite 200B
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Tel: 770-640-0034 Fax: 770-640-0307
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03/01/02
DS21477B-page 18
2002 Microchip Technology Inc.
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