ST AEK-POW-LDOV01J, Руководство пользователя

Страница: 9 / 37

Figure 8. LDO driver finite state machine
The AEK-POW-LDOV01x states are:
•
IDLE : initial state at power-up
• POWER ON : this state is reached when the AEK-POW-LDOV01x is enabled (through the pulse signal
applied to the EN pin)
• POWER OFF : this state is reached when the AEK-POW-LDOV01x is disabled (through the high signal
applied to the EN pin)
• RESET : this state detects a falling reset signal. It returns to the normal state when the V
O
output voltage
rises above V
OTH
and the watchdog frequency value is correct (for the AEK-POW-LDOV01J only)
• ERROR : the FSM enters this state when the absolute value of the difference between the V
O
voltage output
(read by the SARADC-12 bit) and the voltage output reference (selected by the SELx pin) is greater than a
voltage threshold equal to 5% of the voltage reference. In this state, the system is in a dangerous condition
and the LDO should be disabled
• NORMAL : this is the state of normal operating conditions. In this state, the AEK-POW-LDOV01x software
library is able to detect the thermal and overvoltage warning events (for the AEK-POW-LDOV01J
only).When the normal state is active, the AEK-POW-LDOV01x software library generates a WI (watchdog)
signal by using the E-MIOS peripheral with a fixed frequency whose value depends on the SELx
configuration pin (for the
AEK-POW-LDOV01J only)
Note: The AEK-POW-LDOV01x software library supports both AEK-POW-LDOV01J and AEK-POW-LDOV01S
evaluation boards. If the user selects the AEK-POW-LDOV01S , the watchdog signal generation (WI), thermal,
and overvoltage detection events are disabled.
3.3.1 Init device
At power-up, the AEK-POW-LDOV01x initializes the E-MIOS peripheral in the microcontroller to generate the WI
signal (for the
AEK-POW-LDOV01J only). The second step consists in initializing the ADC (SARADC-12bit) used
to read and monitor the V
O
output voltage provided by the voltage regulator.
The AEK-POW-LDOV01x software library includes a unique
Init
instruction with the following prototype:
void AEK_POW_LDOV01x_init(uint8_t AEK_POW_LDOV01x_n_device);
where the
AEK_POW_LDOV01x_n_device
represents the allocated AEK-POW-LDOV01x board.
Note: You can invoke
void AEK_POW_LDOV01x_initAll()
to initiate all the boards allocated.
3.3.2 Power on
The AEK-POW-LDOV01x activation requires an enable on transaction of the FSM (see Section 2.2 ).
The AEK-POW-LDOV01x software library includes the following power on instruction:
void AEK_POW_LDOV01x_power_on(uint8_t AEK_POW_LDOV01x_n_device);
, where the
AEK_POW_LDOV01x_n_device
represents the allocated AEK-POW-LDOV01x board.
UM3028
AEK-POW-LDOV01x software library architecture
UM3028 - Rev 1
page 9/37