Specifications

L70 Hardware Design

L70_HD_V1.0 - 18 -

The restart timing has been illustrated in Figure 5.

<0.8V

>2.0V

Pulldown

> 10ms

VCC

VRESET

(INPUT)

<170ms

Figure 5: Timing of restarting system

3.6. Power saving modes

3.6.1. Standby mode

Standby mode is one of the power saving modes, in this mode, the UART serial port is still accessible,

but has no NEMA messages output, the current consumption of the module is also minimal. The

following table has shown the ways how to enter and exit from the standby mode.

Table 7: The ways of entering and exiting from standby mode

Mode

Operation

Enter the

standby mode

Changing the level of EXTINT0 pin from high to low.

Sending the MTK proprietary command“$PMTK l61,0*28 ”.

Exit from

standby mode

Changing the level of EXTINT0 pin from low to high.

Sending any byte through the UART port.

Note: Recommended to pull EXTINT0 pin high before turning on the module.

3.6.2. Back up mode

When cutting off the main power supply, the module will enter the backup mode. In this mode, the

RTC (Real Time Clock) power supply is needed. It can supply power for backed-up memory which

contains all the necessary GPS information for quick start-up and a small amount of user configuration

variables. The RTC power supply of module can be directly provided by an external capacitor or

battery (rechargeable or non-chargeable) through the V_BCKP pin.

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