Datasheet

LM10506
www.ti.com SNVS729E –SEPTEMBER 2011–REVISED MARCH 2013
Device Operating Modes
STARTUP SEQUENCE
The startup mode of the LM10506 will depend on the input voltage. Once VIN reaches the UVLO threshold, there
is a 15 msec delay before the LM10506 determines how to set up the buck regulators. If V
IN
is below 3.6V, then
Buck 1 and Buck 2 will be in bypass mode, see Bypass-FET Operation on Buck 1 and Buck 2 (Applies to Buck 1
only on LM10506-B) for functionality description. If the VIN voltage is greater than 3.6V the bucks will start up as
the standard regulators. The 3 buck regulators are staggered during startup to avoid large inrush currents. There
is a fixed delay of 2 msec between the startup of each regulator.
The Startup Sequence will be:
1. 15 msec (±30%) delay after V
IN
above UVLO
2. LDO → 3.2V → 3.2V
3. 2 msec delay
4. Buck 1 → 3.0V → 3.0V
5. 2 msec delay
6. Buck 2 → 3.0V or if H/L_B2 = Low → 1.8V
– (For LM10506-A Buck 2 → 2.0V or if H/L_B2 = Low → 1.8V)
7. 2 msec delay
8. Buck 3 → 1.2V or if H/L_B3 = Low → 1.0V
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