TC620HEPA Microchip Technology, TC620HEPA Datasheet - Page 5

• Manufacturer Part Number: TC620HEPA
• Description: IC TEMP SNSR 5V DUAL TRIP 8-DIP
• Manufacturer: Microchip Technology

Specifications of TC620HEPA

• Sensing Temperature: -40°C ~ 85°C
• Output Type: Active High
• Voltage - Supply: 4.5 V ~ 18 V
• Accuracy: ±1°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Temperature Threshold: Programmable
• Supply Voltage (max): 18 V
• Supply Voltage (min): 4.5 V
• Description/function: 5 V, Dual Trip Point Temperature Sensor
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Supply Current: 400 uA
• Ic Output Type: Inverted
• Sensing Accuracy Range: ± 3°C
• Temperature Sensing Range: -40°C To +85°C
• Supply Voltage Range: 4.5V To 18V
• Sensor Case Style: DIP
• No. Of Pins: 8
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.0
The TC620 has a positive temperature coefficient tem-
perature sensor and a dual threshold detector. Temper-
ature set point programming is accomplished with
external resistors from the HIGH SET and LOW SET
inputs to V
remain low as long as measured temperature is below
set point values. As measured temperature increases,
the LOW LIMIT output is driven high when temperature
equals the LOW SET set point (±3°C max). If tempera-
ture continues to climb, the HIGH LIMIT output is driven
high when temperature equals the HIGH SET set point
(Figure 3-1). The CONTROL (hysteresis) output is
latched in its active state at the temperature specified
by the HIGH SET resistor. CONTROL is maintained
active until temperature falls to the value specified by
the LOW SET resistor.
FIGURE 3-1:
3.1
The resistor values to achieve the desired trip point
temperatures on HIGH SET and LOW SET are
calculated using Equation 3-1:
EQUATION 3-1:
For example, a 50°C setting on either the HIGH SET
or LOW SET input is calculated using Equation 3-2 as
follows:
EQUATION 3-2:
Care must be taken to ensure the LOW SET program-
ming resistor is a smaller value than the HIGH SET
programming resistor. Failure to do this will result in
erroneous operation of the CONTROL output.
©
Control Output (Heat Option)
Where:
R
T = The desired trip point temperature in degrees
Kelvin.
Control Output (Cool Option
2002 Microchip Technology Inc.
TRIP
R
SET
= Programming resistor in Ohms
= 0.5997 x ((50 + 273.15)
DETAILED DESCRIPTION
High Limit Output
Programming the TC620
Low Limit Output
DD.
High Set Point
Low Set Point
The HIGH LIMIT and LOW LIMIT outputs
R
TRIP
= 0.5997 x T
TC620/TC621 INPUT VS.
OUTPUT LOGIC
Temperature
2.1312
2.1312
) = 133.6kΩ
Care must also be taken to ensure the LOW SET
temperature setting is at least 5°C lower than the HIGH
SET temperature setting.
Figure 3-2 can help the user obtain an estimate of the
external resistor values required for the desired LOW
SET and HIGH SET trip points.
FIGURE 3-2:
3.2
To prevent output "chattering" when measured
temperature is at (or near) the programmed trip point
values, the LOW SET and HIGH SET inputs each have
built-in hysteresis of -2°C below the programmed
settings (Figure 3-3).
FIGURE 3-3:
As shown, the outputs remain in their active state
(hysteresis) until temperature falls an additional 2°C
below the user's setting.
(Set Point 2˚C)
High Limit
or Low Limit
Output
250
200
150
100
50
-55
Set Point
Built-in Hysteresis
-35
-15
TC620/TC621
5
TEMPERATURE (˚C)
TC620 SENSE
RESISTORS VS. TRIP
TEMPERATURE
BUILT-IN HYSTERESIS ON
LOW LIMIT AND HIGH
LIMIT OUTPUTS
25
45
65
DS21439B-page 5
85
105
125