SLVSHP0 July 2024 TLVM14404 , TLVM14406
PRODUCTION DATA
VCC is the output of the internal LDO sub-regulator used to supply the control circuits of the TLVM1440x. The nominal VCC voltage is 3.3V. The VOSNS pin is the input to the internal LDO. Connect this input to VOUT to provide the lowest possible input supply current. If the VOSNS voltage is less than 3.1V, VIN1 and VIN2 directly power the internal LDO.
To prevent unsafe operation, VCC has UVLO protection that prevents switching if the internal voltage is too low. See VCC_UVLO and VCC_UVLO_HYS in the Electrical Characteristics.
VCC must not be used to power external circuitry. Do not load VCC or short VCC to ground. VOSNS is an optional input to the internal LDO. Connect an optional high quality 0.1µF to 1µF capacitor from VOSNS to AGND for improved noise immunity.
The LDO provides the VCC voltage from one of two inputs: VIN or VOSNS. When VOSNS is tied to ground or below 3.1V, the LDO derives power from VIN. The LDO input becomes VOSNS when VOSNS is tied to a voltage above 3.1V. The VOSNS voltage must not exceed both VIN and 12V.
Equation 8 specifies the LDO power loss reduction as:
The VOSNS input provides an option to supply the LDO with a lower voltage than VIN, thus minimizing the LDO input voltage relative to VCC and reducing power loss. For example, if the LDO current is 10mA at 1MHz with VIN = 24V and VOUT = 5V, the LDO power loss with VOSNS tied to ground is 10mA × (24V – 3.3V) = 207mW, while the loss with VOSNS tied to VOUT is equal to 10mA × (5V – 3.3V) = 17mW – a reduction of 190mW.