AT42QT1011 View Datasheet(PDF) - Atmel Corporation
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AT42QT1011 Datasheet PDF : 25 Pages
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If the sensor is wired to a microcontroller as shown in Figure 3-7 on page 11, the microcontroller can reconfigure the
load resistor to either Vss or Vdd depending on the output state of the QT1011, so that the pulses are evident in
either state.
Figure 3-7. Using a Microcontroller to Obtain HeartBeat Pulses in Either Output State (SOT23-6)
Ro
Port_M.x
1 OUT
SNSK 3
Microcontroller
Port_M.y
SNS 4
SYNC/MODE 6
Electromechanical devices like relays will usually ignore the short HeartBeat pulse. The pulse also has too low a duty
cycle to visibly affect LEDs. It can be filtered completely if desired, by adding an RC filter to the output, or if
interfacing directly and only to a high-impedance CMOS input, by doing nothing or at most adding a small noncritical
capacitor from OUT to Vss.
3.9.3
Output Drive
The OUT pin is active high and can sink or source up to 2 mA. When a large value of Cs (>20 nF) is used the OUT
current should be limited to <1 mA to prevent gain-shifting side effects, which happen when the load current creates
voltage drops on the die and bonding wires; these small shifts can materially influence the signal level to cause
detection instability.
AT42QT1010 [DATASHEET]
11
9542I–AT42–05/2013
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