Analog-to-Digital Converter with Bar Graph Display Output ...

Obsolete Device
TC826
Analog-to-Digital Converter with Bar Graph Display Output
Features
General Description
•
•
•
•
•
•
•
•
•
•
•
•
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 valuable than a direct system variable read out. A bar or
moving dot display supplies information precisely without requiring further interpretation by the viewer.
•
•
•
•
Bipolar A/D Conversion
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
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
Device Selection Table
Part Number
Package
Temperature Range
TC826CBU
64-Pin PQFP
0°C to +70°C
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% resolution 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.
Two display formats are possible. The BAR mode display 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.
The dual slope integrating conversion method with
auto-zero phase maximizes noise immunity and eliminates 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 available now for TC826 prototyping work.
© 2005 Microchip Technology Inc.
DS21477C-page 1
TC826
Package Type
OR
BAR 40
BAR 39
BAR 38
BAR 37
BAR 36
60
59
58
57
56
55
54
BAR 31
POL-
61
BAR 32
BAR/DOT
62
BAR 33
HOLD
63
BAR 35
TEST
64
BAR 34
NC
64-Pin PQFP
53
52
51
50
49
NC
1
48
NC
ANALOG
COMMON
2
47
BAR 30
+IN
3
46
BAR 29
-IN
4
45
BAR 28
REF IN
5
44
BAR 27
CREF+
6
43
BAR 26
CREF-
7
42
BAR 25
VDD
8
41
BAR 24
VBUF
9
40
BAR 23
CAZ
10
39
BAR 22
VINT
11
38
BAR 21
VSS
12
37
BAR 20
OSC1
13
36
BAR 19
OSC2
14
35
BAR 18
BP
15
34
BAR 17
BAR 0
16
33
BAR 16
24
25
NC
BAR 2
BAR 3
BAR 4
BAR 5
BAR 6
BAR 7
BAR 8
26
27
28
29
30
31
32
BAR 15
23
BAR 14
22
BAR 13
21
BAR 12
20
BAR 11
19
BAR 9
18
BAR 10
17
BAR 1
TC826CBU
Typical Application
CINT
RINT
1MΩ
61
1MΩ
62
CAZ
9
VBUF
10
CAZ
11
VINT
CREF+
BAR/DOT
6
CREF
1.0mf
CREF- 7
OSC1 13
HOLD
ROSC
430kΩ
TC826
63
12
OSC2 14
TEST
BP
VSS
OR
REF ANALOG
BAR 0IN COMMON -IN +IN BAR 40 POL-
VDD
8
5
R1
9V
2
4
3
R2
-IN +IN
2V
Full Scale
200mV
Full Scale
20mV
Full Scale
RINT
2MΩ
20kΩ
20kΩ
0.033mf
Component
DS21477C-page 2
CINT
0.033mf
0.033mf
CREF
1mf
1mf
1mf
CAZ
0.068mf
0.068mf
0.014mf
15
59
60
Segment Drive
1MΩ
Backplane
41 Segment LCD
Bar Graph
–
OR
R1 + R2 = 250kΩ
© 2005 Microchip Technology Inc.
TC826
1.0
ELECTRICAL
CHARACTERISTICS
*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.
Absolute Maximum Ratings*
Supply Voltage (V+ to V-)....................................... 15V
Analog Input Voltage (Either Input) (Note 1)... V+ to VPower Dissipation (TA ≤ 70°C)
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
Zero Input
-0
±0
+0
Display
Zero Reading Drift
—
0.2
1
μV/°C
Test Conditions
VIN = 0.0V
VIN = 0.0V
0°C ≤ TA ≤ +70°C
NL
Linearity Error
-1
0.5
+1
Count
Max Deviation from Best Straight Line
R/O
Rollover Error
-1
0
+1
Count
-VIN = +VIN
EN
Noise
—
60
—
μVP-P
VIN = 0V
ILK
Input Leakage Current
—
10
20
pA
VIN = 0V
CMRR
Common Mode Rejection Ratio
—
50
—
μV/V
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
Analog Common Voltage
2.7
2.9
3.35
V
VSD
LCD Segment Drive Voltage
4
5
6
VP-P
VBD
LCD Backplane Drive Voltage
4
5
6
VP-P
IDD
Power Supply Current
—
125
175
μA
VCM = ±1V
VIN = 0V
250kΩ between Common and VDD
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.
© 2005 Microchip Technology Inc.
DS21477C-page 3
TC826
2.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
Pin Number
(64-Pin PQFP)
PIN FUNCTION TABLE
Symbol
Description
1
NC
2
ANALOG
COMMON
Positive analog signal input.
3
+IN
Positive analog signal input.
4
-IN
Negative analog signal input.
5
REF IN
Reference voltage positive input. Measured relative to analog common.
REF IN ≈ Full Scale/2.
6
CREF+
Reference capacitor connection.
7
CREF-
Reference capacitor connection.
8
VDD
Positive supply terminal.
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).
9
VBUF
Buffer output. Integration resistor connection.
10
CAZ
Negative comparator input. Auto-zero capacitor connection.
11
VINT
Integrator output. Integration capacitor connection.
12
VSS
Negative supply terminal.
13
OSC1
Oscillator resistor (ROSC) connection.
14
OSC2
Oscillator resistor (ROSC) connection.
15
BP
16
BAR 0
LCD Backplane driver.
LCD Segment driver: Bar 0.
17
NC
18
BAR 1
LCD Segment driver: Bar 1.
19
BAR 2
LCD Segment driver: Bar 2.
20
BAR 3
LCD Segment driver: Bar 3.
21
BAR 4
LCD Segment driver: Bar 4.
22
BAR 5
LCD Segment driver: Bar 5.
23
BAR 6
LCD Segment driver: Bar 6.
24
BAR 7
LCD Segment driver: Bar 7.
25
BAR 8
LCD Segment driver: Bar 8.
26
BAR 9
LCD Segment driver: Bar 9.
27
BAR 10
LCD Segment driver: Bar 10.
28
BAR 11
LCD Segment driver: Bar 11.
29
BAR 12
LCD Segment driver: Bar 12.
30
BAR 13
LCD Segment driver: Bar 13.
31
BAR 14
LCD Segment driver: Bar 14.
32
BAR 15
LCD Segment driver: Bar 15.
33
BAR 16
LCD Segment driver: Bar 16.
34
BAR 17
LCD Segment driver: Bar 17.
35
BAR 18
LCD Segment driver: Bar 18.
36
BAR 19
LCD Segment driver: Bar 19.
37
BAR 20
LCD Segment driver: Bar 20.
38
BAR 21
LCD Segment driver: Bar 21.
39
BAR 22
LCD Segment driver: Bar 22.
40
BAR 23
LCD Segment driver: Bar 23.
DS21477C-page 4
No connection.
© 2005 Microchip Technology Inc.
TC826
TABLE 2-1:
PIN FUNCTION TABLE (CONTINUED)
Pin Number
(64-Pin PQFP)
Symbol
41
BAR 24
LCD Segment driver: Bar 24.
42
BAR 25
LCD Segment driver: Bar 25.
43
BAR 26
LCD Segment driver: Bar 26.
44
BAR 27
LCD Segment driver: Bar 27.
45
BAR 28
LCD Segment driver: Bar 28.
46
BAR 29
LCD Segment driver: Bar 29.
47
BAR 30
LCD Segment driver: Bar 30.
48
NC
49
BAR 31
LCD Segment driver: Bar 31.
50
BAR 32
LCD Segment driver: Bar 32.
51
BAR 33
LCD Segment driver: Bar 33.
52
BAR 34
LCD Segment driver: Bar 34.
53
BAR 35
LCD Segment driver: Bar 35.
54
BAR 36
LCD Segment driver: Bar 36.
55
BAR 37
LCD Segment driver: Bar 37.
56
BAR 38
LCD Segment driver: Bar 38.
57
BAR 39
LCD Segment driver: Bar 39.
58
BAR 40
LCD Segment driver: Bar 40.
59
OR
60
POL-
61
BAR/DOT
62
HOLD
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.
63
TEST
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
© 2005 Microchip Technology Inc.
Description
No connection.
LCD segment driver that indicated input out-of-range condition.
LCD segment driver that indicates input signal is negative.
Input logic signal that selects BAR or DOT display format. Normally in BAR mode. Connect
to VSS through 1MΩ resistor for DOT format.
No connection.
DS21477C-page 5
TC826
3.0
DETAILED DESCRIPTION
3.1
Dual Slope Conversion Principles
A simple mathematical equation relates the input signal
reference voltage and integration time:
EQUATION 3-1:
The TC826 is a dual slope, integrating analog-to-digital
converter. The conventional dual slope converter measurement cycle has two distinct phases:
1
RC
• Input Signal Integration
• Reference Voltage Integration (De-integration)
∫0
tINT
V T
VIN(t)dt = R RI
RC
Where:
VR = Reference Voltage
VSI = Signal Integration Time (Fixed)
TRI = Reference Voltage Integration Time
(Variable)
The input signal being converted is integrated for a
fixed time period (TSI). 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
is directly proportional to the input signal (TRI)
(Figure 3-1).
In a simple dual slope converter, a complete conversion requires the integrator output to ‘ramp-up’ and
‘ramp-down’.
FIGURE 3-1:
BASIC DUAL SLOPE CONVERTER
C
Integrator
R
Analog Input
Signal
–
–
Comparator
+
+
+/–
Switch Driver
VIN ≈ 1/2 VFULL SCALE
Control
Logic
Clock
Counter
VIN ≈ 1/4 VFULL SCALE
Fixed Signal
Integrate
Time
DS21477C-page 6
Phase Control
Polarity Control
Integrator
Output
REF
Voltage
Variable
Reference
Integrate
Time
Display
© 2005 Microchip Technology Inc.
TC826
FIGURE 3-2:
For a constant VIN:
EQUATION 3-2:
TRI
TSI
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 inherent benefit is noise immunity. Noise spikes are integrated or averaged to zero during the integration
periods. Integrating ADCs are immune to the large conversion errors that plague successive approximation
converters in high noise environments. Interfering signals with frequency components at multiples of the
averaging period will be attenuated (Figure 3-2).
The TC826 converter improves the conventional dual
slope conversion technique by incorporating an autozero phase. This phase eliminates zero scale offset
errors and drift. A potentiometer is not required to
obtain a zero output for zero input.
© 2005 Microchip Technology Inc.
30
Normal Mode Rejection (dB)
VIN = VR
NORMAL MODE
REJECTION OF DUAL
SLOPE CONVERTER
T = Measurement
Period
20
10
0
0.1/T
1/T
Input Frequency
10/T
DS21477C-page 7
TC826
4.0
THEORY OF OPERATION
4.1
Analog Section
The auto-zero cycle length is 19 counts minimum.
Unused time in the de-integrate cycle is added to the
auto-zero cycle.
In addition to the basic signal integrate and deintegrate cycles discussed above, the TC826 incorporates 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 potentiometers. 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
4.1.1
EQUATION 4-1:
The auto-zero loop is opened and the internal differential 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:
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 feedback loop around the offset voltage error compensation.
The voltage level established on CAZ compensates for
device offset voltages.
FIGURE 4-1:
SIGNAL INTEGRATION CYCLE
32
FOSC
TSI =
x 20
FOSC = External Clock Frequency
TC826 ANALOG SECTION
RINT
REF IN
CREF
5
6
7
9
VDD
CINT
CAZ
11
10
8
TC826
AZ
Integrator
–
–
+Input
CMPTR
+
+
3
+
To Digital Section
–
Buffer
Comparator
INT
DE-
DE+
DE+
DE-
AZ
AZ
AZ
Analog
Common
-INPUT
2
INT
VDD
VDD
INT
4
≈ 6.3V
1μA
From
Digital
Control
Center
AZ
INT
DE+
DE-
≈ VDD – 2.9V
–
+
Analog Switch
12
≈ VDD
DS21477C-page 8
© 2005 Microchip Technology Inc.
TC826
4.1.3
The differential input voltage must be within the device
Common mode range when the converter and measured 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.
FIGURE 4-2:
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 integrator output to return to zero. The time required for the
output to return to zero is proportional to the input signal and is between 0 and 40 counts. The digital reading
displayed is:
EQUATION 4-2:
20 =
VIN
VREF
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
VIN
TI
19 Counts
Minimum
20
Counts
One Conversion Cycle = 80 Counts
© 2005 Microchip Technology Inc.
TD ≈ VIN
41 Counts
Maximum
1
)
(TCONV = 80 X
FSYS
DS21477C-page 9
TC826
4.2
System Timing
4.4
The oscillator frequency is divided by 32 prior to clocking the internal counters. The three-phase measurement cycle takes a total of 80 clock pulses. The 80
count cycle is independent of input signal magnitude.
Each phase of the measurement cycle has the following length:
• Auto-Zero Phase: 19 to 59 Counts
For signals less than full scale, the auto-zero is
assigned the unused reference integrate time period.
• Signal Integrate: 20 Counts
This time period is fixed. The integration period is:
Components Value Selection
4.4.1
INTEGRATING RESISTOR (RINT)
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 output stage amplifiers will supply a 1μA drive current with
minimal linearity error. RINT is easily calculated for a
1μA full scale current:
EQUATION 4-4:
RINT =
EQUATION 4-3:
VFS
Full Scale Voltage(V)
=
1 x 10 – 6
1 x 10 – 6
Where VFS = Full Scale Analog Input
⎛ 32 ⎞
TSI = 20
⎝ FOSC ⎠
4.4.2
Where FOSC is the externally set clock frequency.
INTEGRATING CAPACITOR (CINT)
• Reference Integrate: 0 to 41 Counts
The integrating capacitor should be selected to maximize integrator output swing. The integrator output will
swing to within 0.4V of VS+ or VS- without saturating.
4.3
The integrating capacitor is easily calculated:
Reference Voltage Selection
A full scale reading requires the input signal be twice
the reference voltage. The reference potential is measured between REF IN (Pin 5) and ANALOG
COMMON (Pin 2).
EQUATION 4-5:
CINT =
TABLE 4-1:
Required Full Scale Voltage
VREF
20mV
10mV
2V
1V
The internal voltage reference potential available at
analog common will normally be used to supply the
converter’s reference. This potential is stable whenever the supply potential is greater than approximately
7V. In applications where an externally generated reference voltage is desired, refer to Figure 4-3.
The reference voltage is adjusted with a near full scale
input signal. Adjust for proper LCD display read out.
FIGURE 4-3:
EXTERNAL REFERENCE
VFS ⎛
640
⎞
RINT ⎝ FOSC x VINT ⎠
Where: VINT = Integrator Swing
FOSC = Oscillator Frequency
The integrating capacitor should be selected for low
dielectric absorption to prevent rollover errors. Polypropylene capacitors are suggested.
4.4.3
AUTO-ZERO CAPACITOR (CAZ)
CAZ should be 2-3 times larger than the integration
capacitor. A polypropylene capacitor is suggested. Typical values from 0.14μF to 0.068μF are satisfactory.
4.4.4
REFERENCE CAPACITOR (CREF)
A 1μF capacitor is suggested. Low leakage capacitors,
such as polypropylene, are recommended.
Several capacitor/resistor combinations for common
full scale input conditions are given in Table 4-2.
V+
8
V+
TC826
REF IN
ANALOG
COMMON
MCP1525
5
2
1μF
2.50V
Reference
(b)
DS21477C-page 10
© 2005 Microchip Technology Inc.
TC826
Comp.
SUGGESTED COMPONENT
VALUES
2V
Full Scale
VREF ≈ 1V
2mV
Full Scale
VREF ≈ 100V
2MΩ
200kΩ
20kΩ
CINT
0.033μF
0.033μF
0.033μF
CREF
1μF
1μF
1μF
CAZ
0.068μF
0.068μF
1.14μF
ROSC
430kΩ
430kΩ
430kΩ
Note: Approximately 5 conversions/second.
In systems where Common mode rejection ratio minimizes error. Common mode voltages do, however,
affect the integrator output level. Integrator output saturation must be prevented. A worse case condition
exists if a large positive VCM exists in conjunction with
a full scale negative differential signal. The negative
signal drives the integrator output positive along with
VCM. For such applications, the integrator output swing
can be reduced below the recommended 2V full scale
swing. The integrator output will swing within 0.3V of
VDD or VSS without increased linearity error.
4.6
Digital Section
The TC826 contains all the segment drivers necessary
to drive a liquid crystal display (LCD). An LCD backplane 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 segment 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.
Over Range
Indication
39
2
1
-0.5 0
-2
-1
0.5 1
2
3
39 39.5 40 40.5
Analog Input
V
(X FS )
40
Differential Signal Inputs
The TC826 is designed with true differential inputs and
accepts input signals within the input stage Common
mode voltage range (VCM). The typical range is V+ -1
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 system) and -IN is connected to analog common (VCOM).
TRANSFER FUNCTION
40
20mV
Full Scale
VREF ≈ 10V
RINT
4.5
FIGURE 4-4:
Digital Display
TABLE 4-2:
4.7
BAR/DOT Input (Pin 61)
The BAR/DOT input allows the user to select the display 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.
4.8
HOLD Input (Pin 62)
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 display continuously displays the previous conversion
results.
The HOLD pin is normally pulled high by an internal
pull-up.
4.9
TEST Input (Pin 63)
The TC826 enters a Test mode with the TEST input
connected to the negative supply (Pin 12). The connection 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 annunciator (POL-) segment will be on, but not flashing.
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 (FOSC/2560).
In the DOT Display mode, OR flashes and all other data
segment drivers are off.
© 2005 Microchip Technology Inc.
DS21477C-page 11
TC826
4.11
Polarity Indication (POL-, Pin 60)
FIGURE 4-6:
The TC826 converts and displays data for positive and
negative input signals. The POL LCD segment driver
(Pin 60) is active for negative signals.
4.12
8
TC826
Oscillator Operation
9V
12
The TC826 external oscillator frequency, FOSC, is set
by resistor ROSC connected between pins 13 and 14.
The oscillator frequency versus resistance curve is
shown in Figure 4-5.
FIGURE 4-5:
30
20
10
CONV (CONV/SEC)
40
14
OSC2
0.1μf
OSCILLATOR
FREQUENCY VS. ROSC
18
TA = 25°C
16
VDD to VSS = 9V
External
Oscillator
A. Single 9V Supply
VDD = 5V
14
12
VDD 8
10
8
TC826
6
13
Power
Supply
Oscillator
0.1μf
4
VSS 12
2
0
13
OSC1
20
50
FOSC (kHz)
EXTERNAL OSCILLATOR
CONNECTION
0
0
2
4
6 8 10 12 14 16 18 20
ROSC (X 100kΩ)
B. Dual Supply
4.13
FOSC is divided by 32 to provide an internal system
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 display flash rate during an input out-of-range signal is set
by dividing FSYS by 320.
The internal oscillator may be bypassed by driving
OSC1 (Pin 13) with an external signal generator. OSC2
(Pin 14) should be left unconnected.
The oscillator should swing from VDD to VSS in single
supply operation (Figure 4-6). In dual supply operation,
the signal should swing from power supply ground to
VDD.
VSS = 5V
LCD Display Format
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.
FIGURE 4-7:
DISPLAY OPTION
FORMATS
A. BAR Mode
2. Input = 5%
of Full Scale
1. Input = 0
Bar 4
Bar 3
Bar 2
Bar 1
Bar 0
Off
Off
Off
Off
On
Off
Off
On
On
On
B. DOT Mode
1. Input = 0
Bar 4
Bar 3
Bar 2
Bar 1
Bar 0
DS21477C-page 12
2. Input = 5%
of Full Scale
Off
Off
Off
Off
On
Off
Off
On
Off
Off
© 2005 Microchip Technology Inc.
TC826
4.14
BAR Format
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 example, would be displayed with BAR 0 to BAR 20 on.
4.15
DOT Format
By connecting BAR/DOT to VSS through a 1MΩ resistor, the DOT mode is selected. Only the BAR LCD segment equaling the input signal is on. The zero segment
is on for zero input.
4.17
Additional drive electronics are not required to interface
the TC826 to an LCD display. The TC826 has an onchip backplane generator and driver. The backplane
frequency is:
FBP = FOSC/256
Figure 4-8 gives typical backplane driver rise/fall time
versus backplane capacitance.
FIGURE 4-8:
This mode is useful for moving cursor or ‘needle’ applications.
9
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 standard TC826 LCD display is available from Varitronix.
Varitronix Ltd. LCDs
4/F Liven House
61-63 King Yip Street
Kwun Tong, Kowloon
Hong Kong
Tel: (852)2389-4317
Fax: (852)2343-9555
USA Office:
VL Electronics / Varitronix
3250 Wilshire Blvd., Suite 901
Los Angeles, CA 90010
Tel: (213) 738-8700
Fax: (213) 738-5340
• Part No.: VBG-413-DP
BACKPLANE DRIVE RISE/
FALL TIME VS.
CAPACITANCE
10
Rise/Fall Time (X 100ns)
4.16
LCD Backplane Driver (BP, Pin 15)
8
TA = 25°C
VS = 9V
7
6
5
4
3
2
1
0
4.18
1 2 3 4 5 6 7 8 0 10
Backplane Capacitance (X 100pf)
Flat Package Socket
Sockets suitable for prototype work are available. A
USA source is:
Nepenthe Distribution
2471 East Bayshore, Suite 520
Palo Alto, CA 94303
Tel: 415/856-9332
Telex: 910/373-2060
• ‘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.
© 2005 Microchip Technology Inc.
DS21477C-page 13
TC826
5.0
PACKAGING INFORMATION
5.1
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
64-Pin PQFP
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
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)
PIN 1
.018 (0.45)
.012 (0.30)
.041 (1.03)
.031 (0.78)
.555 (14.10)
.547 (13.90)
.687 (17.45)
.667 (16.95)
.031 (0.80) TYP.
.555 (14.10)
.547 (13.90)
.687 (17.45)
.667 (16.95)
.010 (0.25) TYP.
.120 (3.05)
.100 (2.55)
.130 (3.30) MAX.
Dimensions: mm (inches)
DS21477C-page 14
© 2005 Microchip Technology Inc.
TC826
NOTES:
© 2005 Microchip Technology Inc.
DS21477C-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 recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.
2.
3.
Your local Microchip sales office
The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277
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.
DS21477C-page 16
© 2005 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
WRITTEN OR ORAL, STATUTORY OR OTHERWISE,
RELATED TO THE INFORMATION, INCLUDING BUT NOT
LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE,
MERCHANTABILITY OR FITNESS FOR PURPOSE.
Microchip disclaims all liability arising from this information and
its use. Use of Microchip’s products as critical components in
life support systems is not authorized except with express
written approval by Microchip. No licenses are conveyed,
implicitly or otherwise, under any Microchip intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,
PICMASTER, SEEVAL, SmartSensor and The Embedded
Control Solutions Company are registered trademarks of
Microchip Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, dsPICDEM,
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR,
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial
Programming, ICSP, ICEPIC, Linear Active Thermistor,
MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM,
PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo,
PowerMate, PowerTool, rfLAB, rfPICDEM, Select Mode,
Smart Serial, SmartTel, Total Endurance and WiperLock are
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
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.
© 2005, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 quality system certification for
its worldwide headquarters, design and wafer fabrication facilities in
Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
© 2005 Microchip Technology Inc.
DS21477C-page 17
WORLDWIDE SALES AND SERVICE
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://support.microchip.com
Web Address:
www.microchip.com
Australia - Sydney
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
India - Bangalore
Tel: 91-80-2229-0061
Fax: 91-80-2229-0062
China - Beijing
Tel: 86-10-8528-2100
Fax: 86-10-8528-2104
India - New Delhi
Tel: 91-11-5160-8631
Fax: 91-11-5160-8632
Austria - Wels
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393
Denmark - Copenhagen
Tel: 45-4450-2828
Fax: 45-4485-2829
China - Chengdu
Tel: 86-28-8676-6200
Fax: 86-28-8676-6599
India - Pune
Tel: 91-20-2566-1512
Fax: 91-20-2566-1513
France - Paris
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79
China - Fuzhou
Tel: 86-591-8750-3506
Fax: 86-591-8750-3521
Japan - Yokohama
Tel: 81-45-471- 6166
Fax: 81-45-471-6122
Germany - Munich
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431
Korea - Gumi
Tel: 82-54-473-4301
Fax: 82-54-473-4302
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
Atlanta
Alpharetta, GA
Tel: 770-640-0034
Fax: 770-640-0307
Boston
Westborough, MA
Tel: 774-760-0087
Fax: 774-760-0088
Chicago
Itasca, IL
Tel: 630-285-0071
Fax: 630-285-0075
Dallas
Addison, TX
Tel: 972-818-7423
Fax: 972-818-2924
Detroit
Farmington Hills, MI
Tel: 248-538-2250
Fax: 248-538-2260
Kokomo
Kokomo, IN
Tel: 765-864-8360
Fax: 765-864-8387
Los Angeles
Mission Viejo, CA
Tel: 949-462-9523
Fax: 949-462-9608
San Jose
Mountain View, CA
Tel: 650-215-1444
Fax: 650-961-0286
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
China - Shunde
Tel: 86-757-2839-5507
Fax: 86-757-2839-5571
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
China - Xian
Tel: 86-29-8833-7250
Fax: 86-29-8833-7256
Malaysia - Penang
Tel: 60-4-646-8870
Fax: 60-4-646-5086
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
Taiwan - Hsin Chu
Tel: 886-3-572-9526
Fax: 886-3-572-6459
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-536-4803
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
Toronto
Mississauga, Ontario,
Canada
Tel: 905-673-0699
Fax: 905-673-6509
10/31/05
DS21477C-page 18
© 2005 Microchip Technology Inc.
Similar pages