
AD5100
Rev. A | Page 21 of 36
POWER REQUIREMENTS
INTERNAL POWER, V
REG
The AD5100 internal power, V
REG
, is derived from V
1MON
and
becomes active when V
2MON
reaches 2.2 V. V
2MON
is used to turn
AD5100 on and off with a different behavior depending on the
V
2MON
monitoring mode selection.
By default, the AD5100 turns on when the voltage at V
2MON
rises
above the logic threshold, V
2MON_ON
. When V
2MON
falls below the
logic threshold, V
2MON_OFF
, AD5100 turns off 2 seconds after
SHDN is deasserted. Note that AD5100 requires 5 μs to start up
and that V
1MON
must be applied before V
2MON
. Extension of the
AD5100 turn-off allows the system to complete any housekeeping
tasks before the system is powered off.
shows the
default V
2MON
and V
REG
waveforms.
Rising Edge Triggered Wake-Up Mode
If rising edge triggered wake-up V
2MON
mode is selected instead,
the AD5100 does not turn off when V
2MON
returns to a logic low.
To configure the part into rising edge triggered mode, set the
V
2MON
off threshold register, Register 0x04[3:1], to 1001.
In this mode, once the part is powered on, it can only be powered
down by an I
2
C power-down instruction or by removing the
supply on the V
1MON
pin. To power down the part over the I
2
C
bus while in rising edge triggered mode, the user must first
ensure that the software power down feature is enabled.
•
Register 0x18[3] = 0: enable software power-down feature
•
Register 0x18[3] =1: disable software power-down feature
The user must then write to Register 0x17[0], to actually power
down the AD5100.
•
Register 0x17[0] = 0: AD5100 not in software power-down
•
Register 0x17[0] = 1: power down AD5100
This feature is for applications that use a wake-up signal.
0
56
92-
018
V
2MON
V
2MON_ON*
V
2MON,IH
t
2SD_HOLD*
t
2SD_HOLD*
t
VREG_OFF_DELAY
t
VREG_OFF_DELAY
t
GLITCH
t
2SD_DELAY*
t
2SD_DELAY*
V
2MON_ON*
V
2MON_OFF*
V
2MON_OFF*
t
VREG_ON_DELAY
SHDN
V
REG
NOTES
1. 6V < V
1MON
< 30V
2. * = PROGRAMMABLE
t
2SD_DELAY*
Figure 18. Internal Power V
REG
vs. V
2MON
Timing Diagrams (Default)