TK11052 Просмотр технического описания (PDF) - Toko America Inc
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TK11052 Datasheet PDF : 12 Pages
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TK11052
APPLICATION HINTS
EXTERNAL RESISTORS Ra , Rb , Rc , and Rd
(6)
The temperature set point (TSET) and hysteresis (TSH) of
the TK11052 are easily set by external resistors Ra , Rb ,
Rc , and Rd. See Figure 1 for clarification of TSET and TSH.
Ra =
Vref x TSH x TC
(0.4925 + TSET x TC) x ISH
=
1.597 x TSH x 6.1 m
(0.4925 + TSET x 6.1 m) x 1.35 µ
TSET
TSH
FIGURE 1
≈ 1183 x TSH x 103
80.74 + TSET
where
I
SH
=
1.35
µA,
T
C
=
6.1
mV
and
V
REF
=
1.597
V
The set voltage (VSET) of the comparator at the set
temperature (TSET) is calculated as follows:
(1)
VSET = 0.4925 + TSET x TC
where TC = 6.1 mV/°C
1. For Set Temperatures ≥ 25 °C
The set voltage (VSET) of the comparator at the reference
voltage and external resistances is calculated as follows:
(2)
VSET =
Rb
Ra + Rb
x VREF
Rb is calculated by Equations (1) and (2), resulting in:
(3)
Rb =
0.4925 + TSET x TC
x
VREF - 0.4925 - TSET x TC
Ra
The hysteresis voltage (VSH) of the comparator can be
calculated as follows:
(4)
( ) VSH =
Ra x Rb
Ra + Rb
x ISH
where ISH = 1.35 µA
Rb is calculated by Equation (4)
(5)
Rb =
Ra x VSH
Ra x ISH - VSH
Ra is calculated by Equations (3) and (5)
Rb is calculated by Equations (3) and (6)
(7)
Rb =
Vref x TSH x TC
(VREF - 0.4925 - TSET x TC) x ISH
=
1.597 x TSH x 6.1 m
(1.597 - 0.4925 - TSET x 6.1 m) x 1.35 µ
≈ 1183 x TSH x 103
181.07 - TSET
Example:
Ra and Rb when set temperature is 85 °C and temperature
hysteresis is 5 °C.
Ra =
1183 x TSH
1183 x 5
x 103 =
x 103
80.74 + TSET
80.74 + 85
= 35.69 k ≈ 36 kΩ
Rb =
1183 x TSH x
181.07 - TSET
103 =
1183 x 5
181.07 - 85
x
103
= 61.57 k ≈ 62 kΩ
2. For Set Temperatures < 25 °C
(8)
Ra
=
VREF x TSH x TC
(0.4925 + TSET x TC - TSH x TC) x ISH
=
1183 x TSH
x 103
80.74 + (TSET - TSH)
Page 8
July 1999 TOKO, Inc.
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