MAX1441 Datasheet, PDF (1/41 Pages) Maxim Integrated Products – Automotive, Two-Channel Proximity and Touch Sensor

19-5310; Rev 0; 7/10
EVAALVUAAILTAIOBNLEKIT
Automotive, Two-Channel Proximity and
Touch Sensor
General Description
The MAX1441 proximity and touch sensor IC is designed
for capacitive proximity sensing in automotive passive
remote keyless entry (PRKE) and other applications.
This device provides signal processing to support
two independent touch/proximity sensor channels. The
device features two open-drain output pins with high-
voltage capability up to 28V, as well as five digital I/Os
to indicate sensing events. During manufacturing, JTAG
programming uses four digital I/Os.
The device uses grounded electrode capacitive sens-
ing to measure capacitance between one of the two
sense pins and the ground. A hand approaching a
sense electrode attached to these sense pins causes
a change in measured capacitance indicating the
presence (touch or proximity) of the object. Active-
guard outputs shield the sense electrode from unwant-
ed sources without adding parasitic capacitance.
Spread-spectrum techniques in the sensor excitation
circuit reduce both electromagnetic emissions and
susceptibility to interfering signals. In addition, the
sensing excitation frequency is programmable from
100kHz to 500kHz in 10kHz steps to avoid interference.
The sensor input signals are converted to a 12-bit
digital data and are available to an on-chip microcon-
troller (FC). The device provides independent offset
compensation of up to 63pF for each input channel.
Each channel can be programmed to 5pF, 10pF, or 20pF
full-scale range.
The device features an internal MAXQ^® microcontroller
with 2kword of flash for user programs and 128 bytes
of SRAM. This feature provides the ability to implement
customized signal processing and discrimination
algorithms that optimize performance in the systems.
The device offers user-configurable general-purpose
digital I/O lines. Power-on-reset (POR) circuitry provides
consistent startup of the device, and a watchdog
timer ensures long-term reliable operation of the user’s
software.
The device is available in a 20-pin TSSOP package and
is specified over the -40NC to +105NC automotive tem-
perature range.
Features
S Low Average Operating Current (100µA at 14V)
S 1.2.fF LSB Capacitance-to-Digital Resolution (5pF
Range)
S 5V to 28V Operation
S 45V Overvoltage Protection
S Sinusoidal Excitation for Reduced EMI Emissions
S Frequency Spreading Operation for Reduced EMI
Susceptibility and Emissions
S Active-Guard-Sense Architecture Provides
Increased Flexibility in System Packaging
S CMOS/LVCMOS-Compatible Outputs
S Embedded µC Supports User-Specified Adaptive
Sense Algorithms
S 2kwords Flash Memory
S 128-Byte SRAM
S ±2kV ESD Immunity on Sensor I/O Lines
S JTAG Serial Interface
S Supports Two Independent Grounded Capacitor
Sensor Inputs
S -12V Reverse Voltage Protection with External
Diode
Applications
PRKE System Proximity Sensing
Object Detection Systems
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX1441GUP/V+ -40NC to +105NC
20 TSSOP
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V Denotes an automotive qualified part.
MAXQ is a registered trademark of Maxim Integrated
Products, Inc.
________________________________________________________________ Maxim Integrated Products   1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.