NXP Semiconductors
UM11227
NTM88 family of tire pressure monitor sensors
UM11227 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 6 — 24 April 2020
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Symbol Pin Function Description
RFGND 17 RF ground Power in the RF output amplifier is returned to the supply through the
RFGND pin. This conductor should be connected to the power supply using
a “star” connection such that each metal trace does not share any load
currents with other supply pins.
RFOUT 18 RF output The RFOUT pin is the RF energy data supplied by the unit to an external
antenna.
PTA0 19 PTA0 / KBI0 / SS_B /
IRQ
The PTA[0] pin is a general-purpose I/O pin. PTA[0] can be configured as a
normal bidirectional I/O pin with programmable pullup or pulldown devices
and/or wake-up interrupt capability. PTA[0] can be configured for external
interrupt (IRQ). The pulldown devices can only be activated if the wake-up
interrupt capability is enabled. User software must configure the general-
purpose I/O pins so that they do not result in “floating” inputs. PTA[0] maps
to keyboard interrupt function bit [0]. When SPI is enabled, PTA0 serves as
SS_B.
X1 20 RF crystal input The X1 pin is for an external 26 MHz crystal to be used by the internal PLL
for creating the carrier frequencies and data rates for the RF pin.
X0 21 RF crystal output The X0 pin is for an external 26 MHz crystal to be used by the internal PLL
for creating the carrier frequencies and data rates for the RF pin.
PTB1 22 PTB1 / TPMCH1 /
AD4
The PTB[1] pin is a general-purpose I/O pin. This pin can be configured
as a nominal bidirectional I/O pin with programmable pullup devices. User
software must configure the general-purpose I/O pins (PTB[1:0]) so that they
do not result in “floating” inputs. PTB1 can be mapped to TPM channel 1, or
to ADC channel 4.
LFB 23 LF input '-' The LF[A:B] pins can be used by the LF receiver (LFR) as one differential
input channel for sensing low-level signals from an external low frequency
(LF) coil. The external LF coil should be connected between the LF[A] and
the LF[B] pins.
Signaling into the LFR pins can place the unit into various diagnostic or
operational modes. The LFR is comprised of the detector and the decoder.
Each LF[A:B] pin always has an impedance of approximately 500 kΩ to GND
due to the LFR input circuitry.
The LFA/LFB pins are used by the LFR when the LFEN control bit is set and
are not functional when the LFEN control bit is clear.
LFA 24 LF input '+' The LF[A:B] pins can be used by the LF receiver (LFR) as one differential
input channel for sensing low-level signals from an external low frequency
(LF) coil. The external LF coil should be connected between the LF[A] and
the LF[B] pins.
Signaling into the LFR pins can place the unit into various diagnostic or
operational modes. The LFR is comprised of the detector and the decoder.
Each LF[A:B] pin always has an impedance of approximately 500 kΩ to GND
due to the LFR input circuitry.
The LFA/LFB pins are used by the LFR when the LFEN control bit is set and
are not functional when the LFEN control bit is clear.
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