3-77
TELCOM SEMICONDUCTOR, INC.
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TC850
FEATURES
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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
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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
μ
P-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 100
μ
V 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.
ORDERING INFORMATION
Part No.
Package
Temperature Range
TC850CLW
TC850CPL
TC850IJL
TC850ILW
44-Pin PLCC
40-Pin Plastic DIP
40-Pin CerDIP
44-Pin PLCC
0
°
C to +70
°
C
0
°
C to +70
°
C
– 25
°
C to +85
°
C
– 25
°
C to +85
°
C
FUNCTIONAL BLOCK DIAGRAM
15-BIT, FAST-INTEGRATING CMOS ANALOG-TO-DIGITAL
CONVERTER
÷
4
REF1
+
–
BUF
INT IN
BUFFER
INTEGRATOR
COMPARATOR
32
31
30
23
24
25
36
34
39
15
8
DB7
TC850
REF
RINT
CINT
INT OUT
IN
+
IN
–
–
+
–
+
6-BIT
UP/DOWN
COUNTER
–
+
REF2
+
DB0
9-BIT
UP/DOWN
COUNTER
. . . .
5
3
WR
CONT/
DEMAND
AMUX
COMMON
22
40
+5V
–5V
18
OSC2
17
7
L/H
6
OVR/
POL
4
RD
1
CS
2
CE
OSC1
SCOA/D
DATA LATCH
OCTAL 2-INPUT MUX
3-STATE DATA BUS
CLOCK
BUS INTERFACE
DECODE LOGIC
TC850-4 11/5/96