26 NXP Semiconductors
33910
6 Functional device operations
6.1 Operational modes
6.1.1 Introduction
The 33910 offers three main operating modes: Normal (Run), Stop, and Sleep (Low Power). In Normal mode, the device is active and is
operating under normal application conditions. The Stop and Sleep modes are low power modes with wake-up capabilities. In Stop mode,
the voltage regulator still supplies the MCU with VDD (limited current capability), while in Sleep mode the voltage regulator is turned off
(VDD = 0 V).
Wake-up from Stop mode is initiated by a wake-up interrupt. Wake-up from Sleep mode is done by a reset and the voltage regulator is
turned back on. The selection of the different modes is controlled by the MOD1:2 bits in the Mode Control Register (MCR). Figure 14
describes how transitions are done between the different operating modes. Table 6 gives an overview of the operating modes.
6.1.2 Reset mode
The 33910 enters the Reset mode after a power up. In this mode, the RST pin is low for 1.0 ms (typical value). After this delay, it enters
the Normal Request mode and the RST pin is driven high. The Reset mode is entered if a reset condition occurs (VDD low, watchdog
trigger fail, after wake-up from Sleep mode, Normal Request mode timeout occurs).
6.1.3 Normal request mode
This is a temporary mode automatically accessed by the device after the Reset mode, or after a wake-up from Stop mode. In Normal
Request mode, the VDD regulator is ON, the RESET pin is High, and the LIN is operating in RX Only mode. As soon as the device enters
in the Normal Request mode an internal timer is started for 150 ms (typical value). During these 150 ms, the MCU must configure the
Timing Control Register (TIMCR) and the Mode Control Register (MCR) with MOD2 and MOD1 bits set = 0, to enter the Normal mode. If
within the 150 ms timeout, the MCU does not command the 33910 to Normal mode, it enters in Reset mode. If the WDCONF pin is
grounded in order to disable the watchdog function, it goes directly in Normal mode after the Reset mode.
6.1.4 Normal mode
In Normal mode, all 33910 functions are active and can be controlled by the SPI interface and the PWMIN pin. The VDD regulator is ON
and delivers its full current capability. If an external resistor is connected between the WDCONF pin and the Ground, the window watchdog
function is enabled. The wake-up input (L1) can be read as digital input or have its voltage routed through the analog-multiplexer.
The LIN interface has slew rate and timing compatible with the LIN protocol specification 2.0, 2.1 and SAEJ2602. The LIN bus can transmit
and receive information. The high-side switches are active and have PWM capability according to the SPI configuration. The interrupts
are generated to report failures for VSUP over/undervoltage, thermal shutdown, or thermal shutdown prewarning on the main regulator.
6.1.5 Sleep mode
The Sleep mode is a low power mode. From Normal mode, the device enters into Sleep mode by sending one SPI command through the
Mode Control Register (MCR), or (VDD low > 150 ms) with VSUV = 0. When in Reset mode, a VDD undervoltage condition with no VSUP
undervoltage (VSUV = 0) sends the device to Sleep mode. All blocks are in their lowest power consumption condition. Only some wake-
up sources (wake-up input with or without cyclic sense, forced wake-up and LIN receiver) are active. The 5.0 V regulator is OFF. The
internal low-power oscillator may be active if the IC is configured for cyclic-sense. In this condition, one of the high-side switches is turned
on periodically and the wake-up input is sampled. Wake-up from Sleep mode is similar to a power-up. The device goes in Reset mode
except the SPI reports the wake-up source and the BATFAIL flag is not set.
6.1.6 Stop mode
The Stop mode is the second low power mode, but in this case the 5.0 V regulator is ON with limited current drive capability. The
application MCU is always supplied while the 33910 is operating in Stop mode. The device can enter into Stop mode only by sending the
SPI command. When the application is in this mode, it can wake-up from the 33910 side (for example: cyclic sense, force wake-up, LIN
bus, wake inputs) or the MCU side (CS, RST pins). Wake-up from Stop mode transitions the 33910 to Normal Request mode and
generates an interrupt except if the wake-up event is a low to high transition on the CS pin or comes from the RST pin.