LM5046 datasheet(21/42 Pages) TI1

21 / 42 page

LM5046

www.ti.com

SNVS703F – FEBRUARY 2011 – REVISED JANUARY 2012

Soft-Stop Off

The Soft-Start Off (SSOFF) pin gives additional flexibility by allowing the power converter to be configured for

hard-stop during line UVLO and hiccup mode condition. If the SS OFF pin is pulled up to the 5V REF pin, the

power converter hard-stops in any fault condition. Hard-stop drives each control output to a low state

immediately. Refer to Table 2 for more details.

Table 2. Soft-Stop in Fault Conditions

Fault Condition

SSSR

UVLO

Soft-Stop

(UVLO<1.25V)

3x the charging rate

OVP

Hard-Stop

(OVP>1.25V)

Hiccup

Soft-Stop

(CS>0.75 and RES>1V)

6x the charging rate

VCC/VREF UV

Hard-Stop

Internal Thermal Limit

Hard-Stop

Note: All the above conditions are valid with SSOFF pin tied to GND. If SSOFF=5V, the LM5046 hard-stops in all

the conditions. The SS pin remains high in all the conditions until the SSSR pin reaches 1V.

Thermal Protection

Internal thermal shutdown circuitry is provided to protect the integrated circuit in the event the maximum rated

junction temperature is exceeded. When activated, typically at 160°C, the controller is forced into a shutdown

state with the output drivers, the bias regulators (VCC and REF) disabled. This helps to prevent catastrophic

failures from accidental device overheating. During thermal shutdown, the SS and SSSR capacitors are fully

discharged and the controller follows a normal start-up sequence after the junction temperature falls to the

operating level (140 °C).

Submit Documentation Feedback

Product Folder Links: LM5046

LM5046 Datasheet(PDF) 21 Page - Texas Instruments