LM3686 datasheet(4/27 Pages) TI

4 / 27 page

1.8V

VOUT-DCDC

VOUT-LILO

FET OF LILO (SMALL NMOS)

IOUT-LILO 7 50 mA

IOUT-LILO > 50 mA

LARGE NMOS

(SMALL NMOS TO LARGE NMOS TRANSITION)

1.2V

LM3686

SNVS520E – AUGUST 2008 – REVISED MAY 2013

www.ti.com

Enable Combinations

EN_DCDC

EN_LILO

EN_LDO

Function

No Outputs

Linear Regulator enabled only (EN_LDO), supply from VIN_LDO, IOUT_MAX = 300

Linear Regulator enabled only LILO supplies from VIN_LDO,

IOUT_MAX = 50 mA, VIN_LDO > = VOUT_LILO

DC-DC converter enabled only

Linear Regulator & DCDC enabled

1) VIN_LILO < VOUT_LILO + 150 mV (typ.), the small NMOS device is active (IMAX

= 50 mA) and supplied by VIN_LDO.

2) If VIN_LILO > VOUT_LILO + 250 mV (typ.), the large NMOS device is active (IMAX

= 350 mA) and supplied by VIN_LILO. Maxium current of DC-DC when EN_LILO =

High is 250 mA(1)(2)

DC-DC converter and linear regulator active.

Linear regulator starts after DC-DC converter.

(1)

The LILO is turned on via a small NMOS device supplied by VIN_LDO . The maximum current is 50 mA when this small NMOS is ON. If

higher current > 50 mA is desired the following condition must be done: EN_DC = HIGH .

(2)

When the switcher is enabled, a transition occurs from the small NMOS to a larger NMOS. The transition occurs when VIN_LILO >

VOUT_LILO + 250 mV. If VIN_LILO < VOUT_LILO + 150 mV, the LILO switches back to small NMOS (Switcher EN = low).

Figure 4. Mode Transition

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

Submit Documentation Feedback

Product Folder Links: LM3686

LM3686 Datasheet(PDF) 4 Page - Texas Instruments