DS2790 Maxim Integrated Products, DS2790 Datasheet - Page 14

• Manufacturer Part Number: DS2790
• Description: Programmable 1-Cell Li-Ion Fuel Gauge and Protector
• Manufacturer: Maxim Integrated Products

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DS2790 POWER MODES
When power is first applied to the DS2790, a Power-on-Reset (POR) circuit transitions the IC to Brown-Out State
where cell voltage is monitored. If V
and begins code execution. Firmware determines if the IC switches to ANALOG State or low-power SLEEP States
when a STOP halts CPU operation.
The DS2790 enters SLEEP state after a CPU STOP if the ADC, the protector, and all internal timers are disabled.
In SLEEP State, all IC operation becomes inactive except for external activity interrupts. Brown-Out detection does
not occur in SLEEP State. Any interrupt generated by 2-wire port communication, external input on ports P0.0 or
P0.1, or a charger detection on PLS will transition the DS2790 from SLEEP to Brown-Out to verify cell voltage
before returning to CPU State. The DS2790 enters ANALOG State after a CPU STOP if any one of the following is
active: the ADC, the protector, the interval timer or the watchdog timer. An external interrupt or an interrupt from
any active internal circuit causes the DS2790 to transition back to CPU State to service the condition.
If the DS2790 is in ANALOG or CPU State, and VDD falls below V
DS2790 enters the Brown-Out State. In Brown-Out State, the processor is halted without changing the instruction
pointer. If V
brown-out interrupt (if enabled). Otherwise, if V
state where it waits for a charger to be applied. When charge voltage is sensed on PLS, the DS2790 returns to the
Brown-Out State where V
Figure 3. DS2790 State Diagram
4
DD
voltage rises above V
ANALOG
ADC & Protector
Mode
Active
Brown-Out
DD
VDD < V
voltage is verified before returning to CPU State.
Analog Circuits Active
CPU STOP
Charger Detect
BO
V
DD
PLS
BO
voltage is above the brown-out threshold V
> V
Inactive
Interrupt
within a time of t
IN
Brown-Out Recovery
IC
+ 0.15V
VDD > V
DD
remains below V
DS2790 Programmable 1-Cell Li-Ion Fuel Gauge and Protector
BO
Brown-Out Timeout
14 of 41
for t
Brown-Out
CPU Mode
SU:OSCI
CPU and Protector
SU:OSCI
Code Execution
Disabled.
t > t
Brown-Out
, the DS2790 returns to CPU state and generates a
SU:OSCI
VDD < V
BO
BO
for t
BO
Analog Circuits Inactive
, a brown-out condition occurs and the
SU:OSCI
CPU STOP
POR
External
Interrupt
BO
, the DS2790 enters an inactive
, the DS2790 enters CPU state
External Interrupts
SLEEP
Mode
Monitored