XE8000EV120 Semtech, XE8000EV120 Datasheet - Page 102

• Manufacturer Part Number: XE8000EV120
• Description: BOARD EVAL FOR SX8722I070TRLF
• Manufacturer: Semtech
• Series: ZoomingADC™r

Specifications of XE8000EV120

• Number Of Adc's: 1
• Number Of Bits: 16
• Data Interface: I²C
• Inputs Per Adc: 7 Single or 4 Differential
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Utilized Ic / Part: SX8722
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: XM8000EV120; XM8000EV120

15.3.3. SX8722 sleep current consumption below 3V Vbat
Below 3 Volts SX8722 enables the internal voltage multiplier to power the ZoomingADC™. This internal voltage multiplier is
automatically enabled when the power supply goes below 3V Vbat.
This voltage multiplier increases SX8722 consumption. This is why the chip consumption in sleep mode with 2.5V supply is
higher than with 5.5V supply.
There is a possibility to consume less current when the Vbat voltage is lower than 3V: the SLEEP signal has to be sent to the
SLEEP pin when Vbat is higher than 3V, and then decrease the Vbat value. In this case, the voltage multiplier is not
activated.
15.3.4. SX8722 sleep current consumption with the 32.768 kHz Xtal
The sleep mode current consumption with the presence of the 32.768 kHz Xtal is around 1µA if the supply voltage is above
3V. Below 3V, the current consumption is around 4 µA because the VMULT is enabled.
In addition to set the precise RC frequency, the presence of an external 32.768 kHz Xtal allows SX8722 sleep current
consumption 3x lower than without the Xtal.
In this case SX8722 main clock is generated by the Xtal.
15.3.5. SX8722 sleep current consumption without the 32.768 KHz Xtal
The current consumption in sleep mode without the 32.768 kHz Xtal is around 3 µA if the supply voltage is above 3V. Below
3V, the current consumption is around 9 µA because the voltage multiplier is enabled. The RC min frequency is set and its
value is around 80 kHz.
15.3.6. How to set SX8722 in sleep mode
I2C sleep
Through the I2C interface, send a write mask command at address 00 and toggle the SLEEP bit of the SXCtrl1 register.
When SX8722 is in sleep mode, send a write mask command at address 00 and toggle the SLEEP bit to restore SX8722
active mode.
WARNING: The I2C SLEEP command does not allow reaching as low current consumption as the SLEEP pin command or writing the
SLEEP pin
Put the SLEEP input signal to VSS, the SLEEP input is active on negative edge.
Is the SX8722 in SLEEP mode?
There are pulses on the READY pin in active mode every 36ms. In sleep mode there is no pulse on the READY pin.
15.3.7. Wake up from sleep mode to active mode
ACS - Revision 4.2
©2008 Semtech Corp.
ADVANCED COMMUNICATIONS & SENSING
Program HALT, SX8722 needs an interrupt to wake up (I2C communication, SLEEP pin signal, reset, etc).
SXCtrl1 register SLEEP bit. The sleep mode called by I2C SLEEP command (0x40) has a current consumption around 80µA.
October 2008
Page 102
High gain acquisition for sensor interface
DATASHEET
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SX8722