AK4184A Datasheet, PDF (10/36 Pages) Asahi Kasei Microsystems – TSC with Keypad Scanner and GPIO Expander

[AK4184A]
■ λονεΫϦʔϯͷҐஔݕग़


λονεΫϦʔϯͷҐஔݕग़(X ࣠ଌఆɺY ࣠ଌఆ)͸ɺ੍ޚίϚϯυʹΑΓ੾Γସ͑·͢ɻҐஔݕग़͸ɺσΟ
ϑΝϨϯγϟϧํࣜʹͳΓ·͢ɻA/D ίϯόʔλͷϑϧεέʔϧ(ΔVREF)͸ɺଌఆର৅࣠ʹҹՃ͞ΕΔిҐ
ࠩ(X ࣠ଌఆͷ৔߹ɺΔVREF = V_XP - V_XN)ʹͳΓ·͢ɻଌఆର৅࣠ͷωΨςΟϒϐϯ(V_XN)ͱɺ΋͏Ұํͷ࣠ͷ
ϙδςΟϒϐϯ(V_XP)ͱͷిҐࠩ(X ࣠ଌఆͷ৔߹ɺΔAIN = V_YP – V_XN)͕ɺA/D ίϯόʔλͷΞφϩάೖྗ(ΔAIN
= (AIN+) - (AIN-))ʹͳΓ·͢ɻΞφϩάೖྗ͸ɺαϯϓϦϯά಺ʹؒظ෦Ωϟύγλʹνϟʔδ͞Ε·͢ɻ
಺෦Ωϟύγλͷνϟʔδ͕ྃ͢׬ΔͱͦΕҎ্ిྲྀ͸ྲྀΕ·ͤΜɻ
಺෦ΩϟύγλʹిՙΛνϟʔδ͢ΔͨΊͷητϦϯά࣌ؒ(αϯϓϦϯά࣌ؒ)͸ɺগͳ͘ͱ΋ 1.5μs ඞཁͰ
͢ɻ·ͨɺADC ͷ࠷େεϧʔϓοτ͸ɺ125kHz Ͱ͢ɻ
Ґஔݕग़͸ɺX ࣠ɾY ࣠ͷ࠲ඪΛ͢ࢉܭΔඞཁ͕͋ΔͨΊɺ࠷௿ 2 ճͷ A/D ม͕׵ඞཁͰ͢ɻσΟϑΝϨϯ
γϟϧํࣜʹΑΔҐஔݕग़࣌ʹ͓͍ͯɺग़ྗίʔυ͸ɺΞφϩάೖྗͱϑϧεέʔϧిѹͱͷൺͰද͞ݱΕ
·͢ͷͰŊόοςϦ౳ʹΑΔγεςϜిిݯѹมಈͷӨڹΛड͚·ͤΜɻ
AVDD
XP-Driver SW ON
X-Plate
XP
Y-Plate
AVDD
YP-Driver SW ON
X-Plate
XP
Y-Plate
VREF+
AIN+
ADC
YP
VREF-
AIN-
XN
VREF+
AIN+
ADC
YP
VREF-
AIN-
XN
XN-Driver SW ON
YN
YN Touch Screen
YN-Driver SW ON
a) X-Position Measurement Differential Mode
b) Y-Position Measurement Differential Mode
λονύωϧ͕ԡ͞ΕΔͱഁઢ෦෼Ͱ X-plateɺY-plate ͕઀ଓ͞Ε·͢ɻ

XP
X-Plate (Top side)
XN
YN
Y-Plate (Bottom side)
YP
c) 4-wire Touch Screen Construction


Figure 4. Ґஔଌఆճ࿏
MS0947-J-00
-10-
2008/04