UNITRODE UC3704 Technical data
This integrated circuit contains a complete signal conditioning system to interface low-level variable impedance transducers to a
digital system. A pair of matched, temperature-compensated current sources are p rovided for balanced transducer excitation followed by a precision, high-gain comparator. The output of this
comparator can be delayed by a user-selectable duration, after
which a second comparator will switch complementary outputs
separately activated for diagnostic operation and has an optional
latch with external rese t capabil ity. An added feature is a high current power source useful as a heater driver in differential temperature sensing applications. The UC3704 is designed for 0°C to
+70°C environments.
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Bridge Transduc er Swit ch
UC3704
FEATURES
• Dual Matched Current Sources
• High-gain Differential Sensing Circuit
• Wide Common-mode Input Capability
• Complementary Digital Open-collector
Outputs
• Externally Programm a ble Time Delay
• Optional Output Latch with Reset
• Built-in Diagnostic Activation
• Wide Supply Voltage Range
• High Current Heater Power Source Driver
DESCRIPTI ON
UC3704 COMPATIBLE SE NSO RS
SENSOR TYPE ACTIVATION SOURCE
Temperature Pressure Force Position Displacement Velocity Shock
Thermistor X X
Sensistor X X
Thermocouple X
Semiconductor X X X
Photo Voltaic X X X
Photo Resistive X X X
Strain Gag e XXXXXX
Piezoelectric X X X X X
Magneto Resistive X X
Inductive XXXX
Hall Effect X X
Capacitive X
BLOCK DIAGRA M
6/93
UC3704
ABSOLUTE MAXI MUM RATING S
CONNECTION DIAGRAM
Supply Voltage ( +V IN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 V
Output Current (each output) . . . . . . . . . . . . . . . . . . . . . . 50 mA
Buffer Power So urce Current. . . . . . . . . . . . . . . . . . . . . 200mA
Compara to r 1 Inputs. . . . . . . . . . . . . . . . . . . . . . . -0.5V to V
REF
DIL-16 (TOP VI EW)
J or N Package
Compara to r 2 Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 5.5V
Remote Activa tion and Reset Inpu ts . . . . . . . . . . . . . . 0 to 5.5V
Power Dissipation at T
A = 25°C . . . . . . . . . . . . . . . . . . 1000mW
Operating Junct ion Te mp era tu re . . . . . . . . . . . -55°C to +150°C
Storage Temperature Range . . . . . . . . . . . . . . -65°C to +150°C
Lead Tempera ture (Solder ing, 10 Seconds) . . . . . . . . . +3 00°C
Note: Unless otherw ise specified, all volta ges are with respect
to ground (Pin 1).
Currents are positiv e into , negat ive out of th e specified
terminal.
Consult Packag in g sect ion of Dat abo ok f or therm al
imitations and con sider at ions of package.
ELECTRICAL CHARACTERISTICS:
Unless otherwise state d, these spe cifica tion s apply for TA = 0°C to +70°C for the
UC3704: V
IH = 15V, TA =TJ.
PARAMETERS TEST CONDITION S MIN TYP MAX UNITS
Power Inputs
Supply Voltage Range 4.2 36 V
Supply Current V
Reference Sec tion ( w ith respect to V
REF Value |VIN - VREF|TJ = 25°C 2.1 2.2 2.3 V
V
V
REF Temperatur e Coeff icie nt Note 1 -1 -2 -3 mV/°C
IN)
Line Regulatio n ∆V
Load Regulation ∆I
Short Circuit Current V
IN = 36V 5 10 mA
IN = 4.2 to 25V 2 10 mV
O = 0 to 4mA 2 10 mV
IN = 36V, VREF = VIN or Ground
±
25 mA
Current Source ( Q1 and Q 2)
Output Cur rent (Note 2) Current Set = 10µA-9-9.5-10µA
Current Set = 200 µA -180 -195 -200 µA
Output Offset Current R
E6 = RE8 = 20kΩ 0
±
1 µA
Comparator One
Input Offs et Vo lta ge
±
±
1
4mV
Input Bias Cur rent -100 -300 nA
Input Offs et Cu rr ent
CMRR V
Voltage gain R
CM = 0 to 12V 60 70 dB
L>150kΩ 70 85 dB
±
60 nA
Delay Current Source 34 40 52 µA
Output Rise Time Overdrive = 10mV, C
D = 15pF, TJ = 20° C 2 V/µs
2
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