EM6819 datasheet(18/154 Pages) EMMICRO

18 / 154 page

EM6819

07 /09 – rev.D

www.emmicroelectronic.com

2.4 POWER MANAGEMENT

The internal voltage regulator and the voltage multiplier assure a constant voltage VREG to the memory cells, GPNVM,

RAM, ROM, the logic, the CPU core and sensible analog cells over the whole voltage range.

For voltages below typ 2.2V the internal voltgage multiplier may become active and deliver the energy to sustain VREG

voltage. While the internal voltage multiplier is enabled the maximum current draw of all VREG supplied peripherals is

limited and the user shall not use operation frequencies above 2MHz nor switch on the 15Mhz RC oscillator.

The flag VSUPLow shows the status of the voltage multiplier, if read ‘1’ it means the multiplier is active and the current

rescrictions apply.On low voltage supply status 1’ the internal voltage multiplier maintains VREG voltage.

Full frequency range can be used as long as VSUPLow = ‘0’, the voltage multiplier is disabled and the logic regulator

maintains VREG stable.

Figure 2, Power Management architecture

2.4.1

BROWNOUT

If enabled, the BrownOut supervises the VREG voltage. As soon as Vreg drop below the minimal safe operation voltage

for core operations and as such underpasses the brownout limits, reset ResBO is asserted. The circuit goes in reset

state and can only recover from reset if the voltage rises above the PwrCheck level. (VPWRCheck > VBrwnout).

The brownout can be disabled by EnBrownOut bit. The function is also automatically stopped in sleep mode if none of

the Bandgap reference, ADC or OPAMP is active.

2.4.2

POWERCHECK

Powercheck is enabled on system power-up, it keeps the circuit in idle state until VREG voltage is sufficient high for

safe core operation.

( VREG > VPWRCheck > VBrwnoutt)

Powercheck is active after

initial power-up,

wake-up from Power-Down,

wake-up from sleep

after any system reset

2.4.3

POR

POR circuitry supervises the supply voltage VSUP at start-up and during all operation modes. As long as VSUP is

below the VPOR voltage the circuit is in reset state. If the VSUP falls below VPOR the circuit will enter reset state even if

brownout was disabled.

At power-up the POR initializes the whole circuit except the RAM and powercheck is initiated.

EM6819 Datasheet(PDF) 18 Page - EM Microelectronic - MARIN SA