UVLO/stdby pin functioning modes
Due to the wide supply voltage range of the TD310, the UVLO function (Under Voltage Lock Out) is
externally adjustable by a resistor bridge.
The bridge rate can be calculated in relation with the expected UVLO protection level as follows :
R1 + R2
= 1.2V (where R1 is the lower resistor of the bridge)
The internal resistor sets the default UVLO value to 12V (*) and might influence the external bridge rate if
the values of the external resistors are too high. Moreover, the internal resistor ratio is accurate, but the
the tolerance on the absolute value of each internal resistor (typically 140k and 1.26M) is about +/-20%.
If an external bridge is used, we recommend to choose resistor values not greater than 10k.
The standby threshold value depends of the UVLO value as follows:
Vstdby = 0.7/1.2 VUVLO
Both UVLO and stdby functions can be inhibited by connecting the UVLO/stdby pin to VCC+ via a pull up
resistor (ex 150kΩ).
The following table summarizes the functions of the TD310 :
Configuration 1 : UVLO/stdby = H
The TD310 is in a normal consumption state (1.5mA), the operational amplifier is normally functioning and
the buffer outputs are determined by the sense comparator inputs, the enable inputs and the buffer inputs.
Configuration 2 : UVLO/stdby = L
The TD310 is in a low consumption state (standby mode 30µA), the buffer outputs are set to low state and
the operational amplifier is in high impedance state.
Configuration 3 : UVLO/stdby = M
The VCC supply voltage is between VUVLO and Vstdby (**). The TD310 remains in a normal
consumption state and the operational amplifier is normally functioning but the buffer outputs and the
alarm pin are set to low state.
(*) If the UVLO level remains unadjusted, it is recommended to bypass the UVLO/stdby pin with a 1nF capacitor.
(**) If the supply voltage falls below Vstdby, the TD310 is set in standby mode (configuration 2).