1
TC850
15-BIT, FAST-INTEGRATING CMOS ANALOG-TO-DIGITAL
CONVERTER
FEATURES
s
s
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15-bit Resolution Plus Sign Bit
Up to 40 Conversions per Second
12 Conversions per Second Guaranteed
Integrating ADC Technique
— Monotonic
— High Noise Immunity
— Auto-Zeroed Amplifiers Eliminate Offset
Trimming
Wide Dynamic Range ...................................... 96dB
Low Input Bias Current ................................... 30pA
Low Input Noise ........................................... 30
µ
V
P-P
Sensitivity ....................................................... 100
µ
V
Flexible Operational Control
— Continuous or On-Demand Conversions
— Data Valid Output
Bus Compatible, 3-State Data Outputs
— 8-Bit Data Bus
— Simple
µ
P Interface
— Two Chip Enables
— Read ADC Result Like Memory
±
5V Power Supply Operation ...................... 20mW
40-Pin Dual-in-Line or 44-Pin PLCC Packages
2
3
4
5
6
7
GENERAL DESCRIPTION
The TC850 is a monolithic CMOS analog-to-digital
converter (ADC) with resolution of 15-bits plus sign. It
combines a chopper-stabilized buffer and integrator with a
unique multiple-slope integration technique that increases
conversion speed. The result is 16 times improvement in
speed over previous 15-bit, monolithic integrating ADCs
(from 2.5 conversions per sec up to 40 per sec). Faster
conversion speed is especially welcome in systems with
human interface, such as digital scales.
The TC850 incorporates an ADC and a
µP-compatible
digital interface. Only a voltage reference and a few noncriti-
cal passive components are required to form a complete 15-
bit plus sign ADC.
CMOS processing provides the TC850 with high-
impedance differential inputs. Input bias current is typically
only 30pA, permitting direct interface to sensors. Input
sensitivity of 100µV per least significant bit (LSB) eliminates
the need for precision external amplifiers. The internal
amplifiers are auto-zeroed, guaranteeing a zero digital output
with 0V analog input. Zero adjustment potentiometers or
calibrations are not required.
The TC850 outputs data on an 8-bit, 3-state bus. Digital
inputs are CMOS compatible; outputs are TTL/CMOS com-
patible. Chip-enable and byte-select inputs combined with
an end-of-conversion output ensures easy interfacing to a
wide variety of microprocessors. Conversions can be per-
formed continuously or on command. In continuous mode,
data is read as three consecutive bytes and manipulation of
address lines is not required.
Operating from
±5V
supplies, the TC850 dissipates only
20mW. It is packaged in 40-pin plastic or ceramic dual-in-
line packages (DIPs) and in a 44-pin plastic leaded chip
carrier (PLCC), surface-mount package.
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FUNCTIONAL BLOCK DIAGRAM
REF2
+
REF1
+
39
34
REF
–
36
–
IN
+
–
IN
COMMON
32
31
30
ANALOG
MUX
+
BUF
25
RINT
INT IN
24
CINT
–5V
INT OUT
23
22
40
+5V
–
BUFFER
+
INTEGRATOR
–
+
COMPARATOR
TC850
A/D
CONTROL
SEQUENCER
6-BIT
UP/DOWN
COUNTER
9-BIT
UP/DOWN
COUNTER
ORDERING INFORMATION
Part No.
TC850CLW
TC850CPL
TC850IJL
TC850ILW
DATA LATCH
÷4
CLOCK
OSCILLATOR
BUS INTERFACE
DECODE LOGIC
OCTAL 2-INPUT MUX
Package
44-Pin PLCC
40-Pin Plastic DIP
40-Pin CerDIP
44-Pin PLCC
Temperature Range
0°C to +70°C
0°C to +70°C
– 25°C to +85°C
– 25°C to +85°C
3-STATE DATA BUS
17
18
5
7
6
3
4
1
2
15
. . . . 8
OSC1
OSC2
CONT/ L/H OVR/ WR
DEMAND
POL
RD
CS
CE
DB0
DB7
8
TC850-4 11/5/96
TELCOM SEMICONDUCTOR, INC.
3-77
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
