C h a r a c t e r i s t i c s ( Ta = 2 5 º C , m e a s u re m e n t f re q u e n c y @ 1 0 k H z u n l e s s o t h e r w i s e s t a t e d )
Characteristics
Humidity metrology range
Voltage supply
Nominal capacitance @ 55% RH
Temperature coefficient
Averaged Sensitivity from 33% to 75% RH
Leakage current (Vcc=5 Volts)
Recovery time after 150 hours of condensation
Humidity Hysteresis
Long term stability
Time constant (33 to 80% RH, still air, @ 63%)
Deviation to typical response curve (10% to 90%) RH)
t
τα
+/-0.5
3
+/-2
5
Symbol
RH
Vs
C
Tcc
C /% RH
I
tr
10
+/-1
0.31
1
177
180
Min
1
Typ
Max
99
10
183
0.01
Unit
% RH
V
pF
pF/°C
pf/% RH
nA
s
% RH
% RH/yr
s
% RH
Ty p i c a l re s p o n s e l o o k - u p t a b l e ( P o l y n o m i a l R e f e re n c e c u r v e ) 1 0 k H z / 1 V
RH (%)
Cp (pF)
RH (%)
Cp (pF)
0
161.6
55
180
5
163.6
60
181.4
10
165.4
65
182.9
15
167.2
70
184.3
20
169.0
75
185.7
25
170.7
80
187.2
30
172.3
85
188.6
35
173.9
90
190.1
40
175.5
95
191.6
45
177.0
100
193.1
50
178.5
Polynomial response of HS1101LF:
C (pF)=C@55 %*( 3.903 10
-8
*RH
3
-8.294 10
-6
*RH
2
+2.188 10
-3
*RH+0.898)
Reversed Polynomial response of HS1101LF:
RH (%) = -3.4656 10
+3
*X
3
+1.0732 10
-4
*X
2
-1.0457 10
+4
*X+3.2459 10
+3
With X=C(read) / C@55%RH
P ro p o r t i o n a l Vo l t a g e O u t p u t C i rc u i t
Block Diagram
Measurement Specialties, Inc.
G
1000 Lucas Way Hampton, VA 23666 USA
G
www.meas-spec.com
G
757-766-1500
G
800-745-8008
G
Fax 757-766-4297
-2-
HS1101LF Relative Humidity Sensor
F re q u e n c y O u t p u t C i rc u i t s
Note: R22=499k
S
/
R4=49.9
S
? / R1=1 k
S
/
RV1=50 k
S
potentiometer /
C1=10nF / C2=2.2nF / C3=100nF
This circuit is the typical astable design for 555. The HS1101LF, used as variable capacitor, is
connected to the TRIG and THRES pin. Pin 7 is used as a short circuit pin for resistor R4.
The HS1101LF equivalent capacitor is charged through R22 and R4 to the threshold voltage
(approximately 0.67Vcc) and discharged through R22 only to the trigger level (approximately
0.33Vcc) since R4 is shorten to ground by pin 7.
Since the charge and discharge of the sensor run through different resistors, R22 and R4, the dut
cycle is determined by:
-
thigh = C@%RH*(R22+R4)*ln2
- tlow= C@%RH*R22*ln2
- F = 1/(thigh+tlow) = 1/(C@%RH*(R4+2*R22)*ln2)
- Output duty cycle = thigh*F = R22/(R4+2*R22)
To provide an output duty cycle close to 50%, R4 should be very low compared to R22 but never
under a minimum value. Resistor R3 is a short circuit protection. 555 must be a CMOS version.
Ty p i c a l re s p o n s e l o o k - u p t a b l e ( H u m i d i t y O u t p u t )
RH (%)
Fout (Hz)
RH (%)
Fout (Hz)
55
6600
60
6550
0
5
10
7155
65
6500
15
7080
70
6450
20
7010
75
6400
25
6945
80
6355
30
6880
85
6305
35
6820
90
6260
40
6760
95
6210
45
6705
100
50
6650
Measurement Specialties, Inc.
G
1000 Lucas Way Hampton, VA 23666 USA
G
www.meas-spec.com
G
757-766-1500
G
800-745-8008
G
Fax 757-766-4297
-3-
HS1101LF Relative Humidity Sensor
M e a s u re m e n t E r ro r v s S t r a y C a p a c i t a n c e
-Special attention is required in order to
minimize stray capacitance in the layout. The
added capacitance will act as a parallel
capacitance with the sensor and create a
measurement error.
-A careful coating of PCB and components
must be implemented to prevent unexpected
deviations of Fout in high humidity conditions.
Q u a l i f i c a t i o n P ro c e s s
HS1101LF sensors have been qualified through a complete qualification process taking in account many of the requirements of the JEDEC standard including:
•
•
•
•
•
•
•
Solder heat and solderability including lead free process.
Pb free wave soldering and reflow soldering process(260°C) + DI water clean at 45°C
Mechanical shock JESD-22-B104-A
Vibration - Variable frequency(20 to 2000Hz) JESD-22-B103-A
编程基础
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