MCP355XDV-MS1 Datasheet, PDF (19/36 Pages) Microchip Technology – Low-Power, Single-Channel 22-Bit Delta-Sigma ADCs

Once a power-up event has occurred, the device must
require additional time before a conversion can take
place. During this time, all internal analog circuitry must
settle before the first conversion can occur. An internal
timer counts 32 internal clock periods before the
internal oscillator can provide clock to the conversion
process. This allows all internal analog circuitry to
settle to their proper operating point. This timing is
typically less than 300 µs, which is negligible compared
to one conversion time (e.g. 72.7 ms for the
MCP3551). Figure 4-6 illustrates the conditions for a
power-up and power-down event under typical start-up
conditions.
V_DD
2.2V
2.0V
300 µs
MCP3550/1/3
4.8 Sleep Mode
During Sleep mode, the device is not converting and is
awaiting data retrieval; the internal analog circuitry is
still running and the device typically consumes 10 µA.
In order to restart a conversion while in Sleep mode,
toggling CS to a logic-high (placing the part in Shut-
down mode) and then back to a logic-low will restart the
conversion. Sleep can only be entered in Single
Conversion mode. Once a conversion is complete in
Single Conversion mode, the device automatically
enters Sleep mode.
0V
Reset Start-up
Normal
Operation
Reset
Time
FIGURE 4-6:
Power-On Reset Operation.
4.7 Shutdown Mode
When not internally converting, the two modes of
operation for the MCP3550/1/3 devices are the
Shutdown and Sleep modes. During Shutdown mode,
all internal analog circuitry, including the POR, is turned
off and the device consumes less than 1 µA. When
exiting Shutdown mode, the device must require
additional time before a conversion can take place.
During this time, all internal analog circuitry must settle
before the first conversion can occur. An internal timer
counts 32 internal clock periods before the internal
oscillator can provide clock to the conversion process.
This allows all internal analog circuitry to settle to their
proper operating point. This timing is typically less than
300 µs, which is negligible compared to one conversion
time (72.7 ms for MCP3551).
© 2009 Microchip Technology Inc.
DS21950E-page 19