RedWave Labs LTC25 User manual

Operating manual
Linear
Temperature
Controllers
LTC25, LTC50
and LTC100

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Contents
Introduction................................................................................................................................................................................3
Training and support..................................................................................................................................................................4
Absolute Maximum Ratings.......................................................................................................................................................4
Mechanical Information .............................................................................................................................................................4
Electrical Characteristics ............................................................................................................................................................5
Main Connector Characteristics .................................................................................................................................................6
Status LED .................................................................................................................................................................................7
Jumper settings (Connector J3) .................................................................................................................................................7
Set Point ....................................................................................................................................................................................8
PI Control ...................................................................................................................................................................................8
Current Limit ..............................................................................................................................................................................8
Set Point Error Monitor ..............................................................................................................................................................9
Sensor options............................................................................................................................................................................9
Sensor failsafe operation..........................................................................................................................................................10
Sensor PTC and NTC choices ..................................................................................................................................................10
Power dissipation.....................................................................................................................................................................10
Installation................................................................................................................................................................................11
Cable LTC-CBL (optional) ........................................................................................................................................................11
Certification ..............................................................................................................................................................................11
Warranty and returns ...............................................................................................................................................................11
Return procedure .....................................................................................................................................................................12
Revisions..................................................................................................................................................................................12

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Introduction
RedWave Labs Linear Temperature Controllers come in three versions: LTC25,
LTC50 and LTC100 with maximum current capabilities of 2.5A, 5A and 10A
respectively, single supply operation (+5 to 30V) and temperature stability down to
0.001K. All models feature a variable current limiter up to the maximum current,
various sensor capabilities (thermistors, RTDs, AD590, LM335), variable P-I
setting, LED monitors and remote shutdown.
Features
Linear Temperature Control for Thermo-Electric Elements and Resistive Heaters
Applications
Laser, Detectors, Precision Instrument, OEM applications
Specifications
Parameter
Value
LTC 100
LTC50
LTC25
Power
Single
+5 V to 30 V (Vdd)
Input sensor
NTC, PTC thermistor
10μA, 100μA, 200μA,1 mA activation current
AD590
1μA/K output, LTC has 10.0 KOhm load resistor
RTDs
1mA, 10mA activation current
LM135
10 mV/K output, 1 mA activation current
Compliance voltage
Smaller of 5V or Vdd-0.5V
Temperature
Internal Set point
11 turn potentiometer 0-5V, jumper selected
External Set point
0-5 V through 14 pin connector, jumper selected
Stability Over 1 hour
0.001 C (with 20 K thermistor)
Output
Bipolar current
+/-10A
+/-5A
+/-2.5A
Current limit
Symmetrical 0 to Imax
Compliance voltage
Vdd-2.5V
Vdd-1V
Vdd-0.5V
P-I control
Proportional (2-100 A/V) and Integral (0.55-5 A/(V x sec)
Heat dissipation
60 W maximum without heatsink
Security
Disable current if sensor voltage drops below 0.4V
Connector
14 pin Molex MiniFit
Monitor
Current limit
10 bar LED 0 to Imax
Set point error
Coarse indication of set point error with variable gain
Dimensions (WxHxD)
89 x 89 x 28 mm
Weight
195 g
Storage Temp
-55 to 100 C
Operating Temp
-40 to 85 C
RedWave Labs Ltd keeps improving its products and therefore some specifications can vary.

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Training and support
Remote training and support (via Skype) are available. Please contact [e-mail] for more information.
Absolute Maximum Ratings
Symbol
Parameter
Ratings
Unit
Vdd
Supply voltage
+5 to 30
Volt
Top
Operational Temperature
-40 to 85
Deg C
Tst
Storage Temperature
-55 to100
Deg C
Mechanical Information
Parameter
Value
Unit
Length
3.50 (88.9)
Inch (mm)
Width
3.50 (88.9)
Inch (mm)
Height
1.0 (25.5)
Inch (mm)
Weight
195
Gram

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Electrical Characteristics
Parameter
Comments
Value
Unit
SENSOR
Type
Thermistor (NTC and PTC), RTDs,
LM135/235/335, AD590
Activation current
Activation current
mA
Compliance voltage
Smaller of Vdd−0.5 and 5
V
CONTROL
Set point internal (SPi)
11 turn potentiometer CC increase; selection by
jumper 5 of J3
0 to 5
V
Set point external (SPe)
External Voltage with transfer function 1V/V.
Jumper 6 J3
0 to 5
V
Set point ext+int
Set voltage is equal to 0.5×(Spi+SPe)
0 to 5
V
Proportional Gain Gp
1 turn potentiometer
2 to 100
V / A
Integral Gain Gi
1 turn potentiometer
0.5 to 5
A(V×s)
Set point accuracy
20 KOhm thermistor, critically dump system
1
mV
Temperature stability
1 hour
0.001
°C
External control
Provides direct control of current: 1.5 V→3.5 V: -
Imax→Imax; jumper 8 of J3
Internal PI
Uses Proportional Gain Gp and Integral Gain Gi to
control driving current
Power current enable
Pin 13 J3; 0V enable; 5V disable
POWER CURRENT
Type
Range
LTC-25, LTC-50, LTC-100 accordingly
+/-2.5,+/-5,+/-10
A
Current limit
1 turn potentiometer with LED bar indicator
Linear 0 to 100,
symmetrical
%
Voltage compliance
LTC-25, LTC-50, LTC-100 accordingly
Vdd-0.5; Vdd-1; Vdd-2.5;
V
Master / slave capability
Slave unit can be driven from Actual TEC current
monitor
Heat dissipation
At 25°C
60
W
Shutdown mode current
60
mA
MONITOR SIGNALS AND INDICATORS
Set point temperature
Fully buffered
0 to Vdd−1.4
V
Actual point temperature
Fully buffered
0 to Vdd−1.4
V
Actual TEC current
Fully buffered; 2.5 V “0” point
1.5 to 3.5
V
Actual TEC monitor transfer
function
2.5+A×Iactual
A=0.4 (LTC−25);
A=0.2 (LTC−50);
A=0.1 (LTC−100)
V / A
Current limit monitor
10 Segment LED Bar
0 to Imax
A
Set point –Actual Temp
Error
10 Segment LED Bar, Gain varies from 0.25V
down to 0.05V per one segment

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Main Connector Characteristics
PIN#
Abbreviation
Name
Description
1
Power GND
Power Ground/
Negative Power Pin
Power Ground for TEC power. Electrically connected to Pin 3 (Monitor
GND) and Pin 14 (Sensor GND). Pin1 is the only pin that can be used
for the return path of the TEC (Heater) driving current
2
Power V+
Positive power supply/
Positive power pin
Power Ground for TEC power. Electrically connected to Pin 3 (Monitor
GND) and Pin 14 (Sensor GND). Pin1 is the only pin that can be used
for the return path of the TEC (Heater) driving current
3
GND
Monitor Ground pin
Pin is used for monitoring circuits. This pin must not be connected to
the Power Ground (Pin1).
4
Monitor
Temperature
Temperature Monitor
Pin
Fully buffered Actual Temperature. Output range is the smaller of
0→Vdd-1.4V and 0→5V. Ext
5
Set Temperature
Temperature Set Pin
Pin is used to set the External Temperature. Selected by jumpers.
Voltage range 0→5V
6
Monitor TEC
current
Monitor TEC current
Pin provides voltage corresponding to the actual TEC(heater) current.
Range 2.5+A×Iactual(A=0.4;0.2; 0.1for LTC-25; LTC-50 and LTC-
100 accordingly)
7
Sensor+
Sensor Positive
Positive pin for the sensor current supply and sensing
8
TEC+
Positive TEC Power
PIN
Positive Thermo-electric cooler power pin. For Resistive Heaters one
side of the heater should be connected to the TEC+ or TEC- pin and
the other side should be connected to the same power supply as Pin
2( Power V+). Correct heating polarity will depend on the sensor
(NTC or PTC). Correct feedback direction can be adjusted with
Jumpers 1-4 (Positive/Negative sensor) of J3.
9
TEC-
Negative TEC
Negative Thermo-electric Cooler pin. For Resistive Heaters one side of
the heater should be connected to the TEC+ or TEC- pin and the other
side should be connected to the same power supply as Pin 2( Power
V+). Correct heating polarity will depend on the sensor (NTC or PTC).
Correct feedback direction can be adjusted with Jumpers 1-4
(Positive/Negative sensor) of J3
10
Monitor Set
Temperature
SET Temperature
Monitor Pin
Fully buffered Set Temperature. Output range smaller of 0→Vdd-1.4V
and 0→5V
11
Max Current
Status
Max Current Status
Reached Pin
0V –normal operation; +5V if current limit (any side) is reached
12
Set TEC Current
Set TEC current Pin
Used to set TEC current directly if internal PI control is disabled (J3
Jumper 7 OFF) and external TEC control is enabled (J3 Jumper 8
ON). One of Jumpers 7 or 8 has to be ON. Both jumpers in ON and
both jumpers in OFF position could damage LTC and cooling/heating
element. Transfer function is I=B× (2.5-Vset) A/V where
B=2.5(LTC25), B=5(LTC-50) and B=10 (LTC-100).
13
Set TEC Current
External TEC current
disable Pin
0V-TEC enable; +5V-TEC current disable.
14
Sensor- (GND)
Sensor negative Pin
Sensor negative pin is connected internally to the Power Ground but
is not able to carry high current. This pin should not be used for the
main current return.
The LTC Main Connector is a Molex Mini-Fit p/n 39-30-0140. The mating connector is a Molex Mini-Fit p/n 39-01-2145 with
crimp pins Molex p/n 39-00-0207 or 39-00-0079 for high current (up to 13 A). The Molex suggested crimping tool p/n 63819-
0900 can be purchased, e.g. from Digikey Inc (www.digikey.com).

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Status LED
Status LEDs are used for fast visual assessment of the LTC status. The LED status indicator has 3 separate LEDs located on the
same side as main connector. The default LED colour is red; this can be varied in customized versions.
LED
Abbreviation
Name
Description
Bottom
Power
Power connected
indicator
LED is ON once power is connected.
Mid
TEC Current Off
TEC Current disable
indicator
LED is ON if either: i) external TEC disable signal is applied to
PIN 13 of the Main connector; or ii) sensor voltage drops below
0.4V (safety condition to prevent thermal runway if the sensor is
disconnected)
Top
TEC Current
Limit
TEC Current limit
indicator
LED is ON when Current limit (positive or negative) is reached.
Jumper settings (Connector J3)
Overall jumper setting (J3) are summarized below together with shipping (default) settings. We can provide different default
settings on request.
Type
Selection
Jumpers
Description
‘Negative / Positive’
J3 ‘Negative’
Jumper 1 ON/OFF
Default option: ‘Negative’
Negative’ ‘Positive’
J3 ‘Positive’
Jumper 2 OFF/ON
J3 ‘Negative’
Jumper 3 ON/OFF
J3 ‘Positive’
Jumper 4 OFF/ON
‘Set Point’ ‘Internal /
External / Dual’
J3 ‘Internal’
Jumper 5 ON/OFF/ON
Default option: ‘Internal’
‘Internal’ ‘External’ ‘Dual’
J3 ‘External’
Jumper 6 OFF/ON/ON
‘PI Control’ ‘Internal
/ External’
J3 ‘Internal’
Jumper 7 ON/OFF
Default option: ‘Internal’
‘Internal’ ‘External’
J3 ‘External’
Jumper 8 OFF/ON
‘Sensors’ ‘AD590 /
Other’
J3 ‘AD590’
Jumper 9 ON/OFF
Default option: ‘Other’
‘AD590’ ‘Other’
J3 ‘Other’
Jumper 10 OFF/ON
‘Sensors’
10µA / 100µA /
1mA / 200µA
J3 ‘10µA’
Jumper 11 ON/OFF/OFF/OFF
Default option: ‘100µA’
‘10µA’ ‘100µA’ ‘1mA’ ‘200µA’
J3 ‘100µA’
Jumper 12 OFF/ON/OFF/OFF
J3 ‘1mA’
Jumper 13 OFF/OFF/ON/OFF
J3 ‘200µA’
Jumper 14 OFF/OFF/OFF/ON

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Set Point
The LTC has 3 options to operate with set points. The most common options are to use an internal set point with the 11-turn
potentiometer or to use an external voltage applied to Pin 5 of the Main connector.
Type
Selection
Jumpers
Description
Internal (11-turn
potentiometer)
J3
Jumper 5 ON
Jumper 6 OFF
Internal set point: 0 to 5V set by 11 turn potentiometer located in top
right corner of the cover. Voltage is increased in CW direction
External
J3
Jumper 5 OFF
Jumper 6 ON
External set point: 0 to 5V set by Pin 5 Main Connector
Joint: Internal
and External
J3
Jumper 5 ON
Jumper 6 ON
Set voltage is equal to 0.5 × (SPint+ SPext). For example, if the
internal and external are both equal to 2.5V then the resulting set point
is still 2.5V
PI Control
The LTC has 2 options to control the temperature feedback loop: Internal and External. Internal PI control covers the vast
majority of systems and the P and I control potentiometers can be adjusted to obtain the optimal PI. External PI control can be
used if the user has a digital PID implementation elsewhere.
Type
Selection
Jumpers
Description
Internal
Proportional
J3
Jumper 7 ON
Jumper 8 OFF
Internal Proportional Gain setting 2-100 A/V with ¾ turn linear
potentiometer. Gain is increased in CW direction. Shipped with
Proportional Gain=20 A/V.
Internal Integral
J3
Jumper 7 ON
Jumper 8 OFF
Internal Integral Gain setting 0.55-5 A/(×sec)V with ¾ turn linear
potentiometer. Gain is increased in CW direction. Shipped with Integral
Gain=0.5 A/(V×sec)
External
J3
Jumper 7 OFF
Jumper 8 ON
External control of TEC/heater current through Pin 12 of the Main
Connector. Transfer function is I=B×(2.5−Vset) A/V where
B=2.5(LTC-25), B=5(LTC-50) and B=10 (LTC-100). Maximum
current is limited by the current limit setting. If Vset is outside 1.5V
to3.5V range but less than Vdd, no damage will occur.
Proportional and Integral gains can be measured using 3 test points ( Common ‘C’, Proportional ‘P’, and Integral ‘I’) on the top
right corner close to the P and I potentiometers. The Proportional gain (A/V) can be calculated using the value of the resistance
between ‘C’ and ‘P’ test points and expressed in kOhm:
𝐺𝑝𝑟𝑜𝑝 =400 − 2 × 𝑅𝑚
4 + 1.98 × 𝑅𝑚
where Rm is the measured resistance.
The Integral gain (A/(V× sec)) can be calculated using the same approach:
𝐺𝑖𝑛 = 0.5 + 4.5
1 + 𝑅𝑚
Current Limit
Current limit is set by the ¾ turn potentiometer located in bottom left corner (top view). Close to it, the LEDx10 bar of running
single LEDs is used to monitor actual current limit. If there is no indicator, the current limit is close to 0% and the Current Limit

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Linear Temperature Controllers LTC25, LTC50 and LTC100
potentiometer should be turned slightly in CW direction. In the table below Current Limit is expressed in %. For absolute current
limits, the maximum current for the given LTC model should be multiplied by the percentage value given in the table below.
Current Limit
Current Limit Monitor
0
No bar illuminated
10%
Transition to the 1st bar
20%
Transition to the 2nd bar
30%
Transition to the 3rd bar
40%
Transition to the 4th bar
50%
Transition to the 5th bar
60%
Transition to the 6th bar
70%
Transition to the 7th bar
80%
Transition to the 8th bar
90%
Transition to the 8th bar
100%
Fully open CW direction
Set Point Error Monitor
A LEDx10 bar monitors the actual error between set point and actual sensor voltage. The Error Monitor Gain can be set from
0.25V down to 0.05 V per one LED bar. The Error monitor Gain is increased in CW direction. Please note that the Error Monitor
is a coarse monitoring tool and proper monitoring should be done using Pins 4 and 3 (GND and Temperature Monitor Pins) on
the main connector.
Sensor options
Five different setting have been implemented to accommodate various temperature sensors available on the market today.
AD590 requires an external voltage to operate properly; all other sensors require constant current activation.
Type
Selection
Jumpers
Description
AD590
J3 ‘AD590’
Jumper 9 ON
AD590 is a voltage activated sensor. For proper AD590
sensor operation, the negative pin of AD590 should be
connected to Pin 14 (Main connector) and the positive pin
of AD590 should be connected to the Vdd. AD590 nominal
output is 1µA/K. The LTC (all models) has a 10 KOhm load
resistor so 293K will produce 2.93V voltage.
J3 ‘OTHER’
Jumper 10 OFF
J3 ‘10µA’
Jumper 11 OFF
J3 ‘100µA’
Jumper 12 OFF
J3 ‘1mA’
Jumper 13 OFF
J3 ‘200µA’
Jumper 14 OFF
10 µA, Thermistors
PTC and NTC
3 ‘AD590’
Jumper 9 OFF
10 µA setting is used for resistive sensors (thermistors) both
PTC and NTC types. For example, 100 kOhm thermistor
will produce 1.00V at 10µA current sensing
J3 ‘OTHER’
Jumper 10 ON
J3 ‘10µA’
Jumper 11 ON
J3 ‘100µA’
Jumper 12 OFF
J3 ‘1mA’
Jumper 13 OFF
J3 ‘10mA’
Jumper 14 OFF
100 µA, Thermistors
PTC and NTC
J3 ‘AD590’
Jumper 9 OFF
100 µA setting is used for resistive sensors (thermistors)
both PTC and NTC types.
J3 ‘OTHER’
Jumper 10 ON
J3 ‘10µA’
Jumper 11 OFF
J3 ‘100µA’
Jumper 12 ON
J3 ‘1mA’
Jumper 13 OFF
J3 ‘200µA’
Jumper 14 OFF
1 mA, RTDs,
LM135/235/335
J3 ‘AD590’
Jumper 9 OFF
1 mA setting is used for resistive sensors (thermistors and
RTDs) and LM135/235/335 IC type temperature sensors.
J3 ‘OTHER’
Jumper 10 ON
J3 ‘10µA’
Jumper 11 OFF

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Linear Temperature Controllers LTC25, LTC50 and LTC100
Thermistors PTC and
NTC
J3 ‘100µA’
Jumper 12 OFF
J3 ‘1mA’
Jumper 13 ON
J3 ‘200µA’
Jumper 14 OFF
200 µA, RTDs
J3 ‘AD590’
Jumper 9 OFF
200 µA setting is used for resistive sensors (thermistors)
both PTC and NTC types.
J3 ‘OTHER’
Jumper 10 ON
J3 ‘10µA’
Jumper 11 OFF
J3 ‘100µA’
Jumper 12 OFF
J3 ‘1mA’
Jumper 13 OFF
J3 ‘200µA’
Jumper 14 ON
Sensor failsafe operation
If the sensor voltage drops below 0.4V then the TEC power current is disabled, the ‘TEC current disable’ LED is ON and Pin 6
of Main Connector (TEC Current Monitor) goes to 2.5V (No current). Once the sensor voltage goes above the threshold then
normal operation resumes automatically.
Sensor PTC and NTC choices
The LTC has an option for the user to select the type of sensor (Negative or Positive Temperature Coefficient) with the J3 jumper
selection. This allows to adjust the feedback system polarity response. Users can choose between two options: i) set point –
actual sensor voltage, and ii) actual sensor voltages − set point. The feedback polarity adds an additional degree of flexibility to
wiring.
Type
Selection
Jumpers
Description
‘Negative’
J3 ‘Negative
Jumper 1 ON
Operation for NTC sensors and normal operation of the TEC
J3 ‘Positive’
Jumper 2 OFF
J3 ‘Negative
Jumper 3 ON
J3 ‘Positive’
Jumper 4 OFF
‘Positive’
J3 ‘Negative
Jumper 1 OFF
Operation for PTC sensors and normal operation of the TEC
J3 ‘Positive’
Jumper 2 ON
J3 ‘Negative
Jumper 3 OFF
J3 ‘Positive’
Jumper 4 ON
Power dissipation
LTC controllers have been designed to handle 60 Watt power dissipation without heat sink under normal atmospheric conditions.
Users must calculate the maximum heat load on the controller properly before starting continuous operation. Typical steps to
calculate maximum heat load are given below
•Obtain the load curve of the load as function of the current. Typically most of the TECs or resistive heaters follow a
standard ohmic law: Uload = R load × I , but non-linear loads could cause variations.
•Measure supply voltage Udd.
•Calculate dissipated power P=I × (Udd-Uload) over the full current range from 0 to Imax. Dissipated power must be below
60W over the full range of current. If at some point dissipated power exceeds 60W then the LTC Controller should be
mounted on an external heatsink.