figaro product information applications: featur es: tgs 2180 - water vapor detection for automatic control of microwave ovens the figure below represents typical sensitivity characteristics, all data having been gathered at standard test conditions (see reverse side of this sheet). the y-axis is indicated as sensor resistance ratio (rs/ro) which is defined as follows: rs = sensor resistance in water vapor at various absolute humidities ro = sensor resistance in clean air at 11.2g/m 3 of absolute humidity (corresponding to 20?c/65%rh) the figure below represents sensitivity to various gases. again, the y-axis is indicated as sensor resistance ratio (rs/ro), defined as follows: rs = sensor resistance in vaious concentrations of gases ro = ro = sensor resistance in clean air at 11.2g/m 3 of absolute humidity (corresponding to 20?c/65%rh) * automatic cooking control in microwave ovens the sensing element is comprised of a metal oxide semiconductor layer formed on an alumina substrate of a sensing chip together with an integrated heater. the tgs 2180 has relatively high sensitivity to water vapor and low sensitivity to organic vapors which may be generated from cooking food. the sensor's conductivity increases depending on absolute humidity. a simple electrical circuit can convert the change in conductivity to an output signal which corresponds to absolute humidity. cooking condition can be detected by monitoring changes in sensor resistance ratio, whcih can be uniquely determined depending on the type of food, but independent from the food's weight. with quick response to water vapor and excellent durability in high temperature operation, tgs 2180 is an ideal sensor for automatic cooking time control in microwave ovens. due to miniaturization of the sensing chip, tgs 2180 requires a heater current of only 166ma and the device is housed in a standard plastic housing package. * low power consumption * high sensitivity to water vapor * high temperature durability * long life and low cost * uses simple electrical circuit * small size sensitivity characteristics to various gases: sensitivity characteristics to water vapor: important note: operating conditions in which figaro sensors are used will vary with each customers specific applications. figaro strongly recommends consulting our technical staff before deploying figaro sensors in your application and, in particular, when customer s target gases are not listed herein. figaro cannot assume any responsibility for any use of its sensors in a product or application for which sensor has not been specifically tested by figaro. 0.1 1 1 10 100 1000 rs/ro absolute humidity (g/m 3 ) 0.1 1 10 10 100 1000 methane iso-butane hydrogen co ethanol air rs/ro concentration (ppm)
structure and dimensions: figaro engineering inc. 1-5-11 senba-nishi mino, osaka 562 japan tel.: (81) 72-728-2561 fax: (81) 72-728-0467 email: figaro@figaro.co.jp basic measuring circuit: rev: 04/04 the sensor requires two voltage inputs: heater voltage (v h ) and circuit voltage (v c ). the heater voltage (v h ) is applied to the integrated heater in order to maintain the sensing element at a specific temperature which is optimal for sensing. circuit voltage (v c ) is applied to allow measurement of voltage (vout) across a load resistor (r l ) which is connected in series with the sensor. dc voltage is required for the circuit voltage since the sensor has a polarity. a common power supply circuit can be used for both v c and v h to fulfill the sensor's electrical requirements. the value of the load resistor (r l ) should be chosen to optimize the alarm threshold value, keeping power consumption (p s ) of the semiconductor below a limit of 15mw. power consumption (p s ) will be highest when the value of rs is equal to r l on exposure to gas. the value of power consumption (p s ) can be calculated by utilizing the following formula: p s = sensor resistance (rs) is calculated with a measured value of vout by using the following formula: r s = - r l specifications: bottom view top view side view v c x r l vout (v c - vout) 2 r s r e b m u n l e d o m0 8 1 2 s g t e p y t t n e m e l e g n i s n e s1 s e g a k c a p d r a d n a t sc i t s a l p s e s a g t e g r a tr o p a v r e t a w e g n a r n o i t c e t e d l a c i p y tm / g 0 5 1 ~ 1 3 t i u c r i c d r a d n a t s s n o i t i d n o c e g a t l o v r e t a e h v h 0 . 5 c a / c d v 2 . 0 e g a t l o v t i u c r i c v c 0 . 5 c d v 2 . 0 s p w m 5 1 e c n a t s i s e r d a o l r l e l b a i r a vk 5 4 . 0 w . n i m l a c i r t c e l e s c i t s i r e t c a r a h c t s e t d r a d n a t s r e d n u s n o i t i d n o c e c n a t s i s e r r e t a e h r h 8 1 2 w . p m e t m o o r t a ) l a c i p y t ( t n e r r u c r e t a e h i h a m 6 6 1 r e w o p r e t a e h n o i t p m u s n o c p h ) l a c i p y t ( w m 0 3 8 e c n a t s i s e r r o s n e s s r k 5 4 1 ~ 3 2 w r i a n i h r % 5 6 / c ? 0 2 t a r o p a v r e t a w o t y t i v i t i s n e s ) s r f o o i t a r e g n a h c ( 1 e t o n 2 9 . 0 ~ 7 7 . 0 h r % 8 6 / c ? 5 2 t a r i a s r h r % 5 6 / c ? 0 2 t a r i a s r h o t e o t y t i v i t i s n e s ) s r f o o i t a r e g n a h c ( 1 1 . 1 ~ 3 8 . 0 ) h o t e m p p 0 0 3 ( s r r i a s r t s e t d r a d n a t s s n o i t i d n o c s n o i t i d n o c s a g t s e t r i a l a m r o n 0 2 t a 5 6 , c ? 2 h r % 5 s n o i t i d n o c t i u c r i c v c 0 . 5 = c d v 5 0 . 0 v h 0 . 5 = c d v 5 0 . 0 d o i r e p g n i n o i t i d n o c t s e t e r o f e b s y a d 2 rs r h rl v 1 2 3 6.0 3.0 20 0.5 4.7 0.2 11.5 0. 2 0.8 0.1 0. 2 2.54 2.54 pin connection: 1: sensor electrode (-) 2: common (+) 3: heater (-) ?2.0 0.5 u/m=mm note 1: absolute humidity at 25?c/68%rh = 15.6g/m 3 absolute humidity at 20?c/65%rh = 11.2g/m 3
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