LM46000PWP datasheet(24/56 Pages) TI2

24 / 56 page

LM46000

SNVSA45B – JUNE 2014 – REVISED MARCH 2018

www.ti.com

Product Folder Links: LM46000

Submit Documentation Feedback

Device Functional Modes (continued)

7.4.4 CCM Mode

CCM operation is employed in the LM46000 when the load current is higher than half of the peak-to-peak

inductor current. In CCM operation, the frequency of operation is fixed unless the minimum HS switch ON-time

(TON_MIN), the minimum HS switch OFF-time (TOFF_MIN) or LS current limit is exceeded. Output voltage ripple is at

a minimum in this mode, and the maximum output current of 0.5 A can be supplied by the LM46000.

7.4.5 Light Load Operation

When the load current is lower than half of the peak-to-peak inductor current in CCM, the LM46000 operates in

DCM , also known as diode emulation mode (DEM). In DCM operation, the LS FET is turned off when the

inductor current drops to 0 A to improve efficiency. Both switching losses and conduction losses are reduced in

DCM, comparing to forced PWM operation at light load.

At even lighter current loads, PFM is activated to maintain high efficiency operation. When the HS switch ON-

time reduces to TON-MIN or peak inductor current reduces to its minimum IPEAK-MIN, the switching frequency reduce

sto maintain proper regulation. Efficiency is greatly improved by reducing switching and gate drive losses.

7.4.6 Self-Bias Mode

For highest efficiency of operation, TI recommends that the BIAS pin be connected directly to VOUT when VOUT ≥

3.3 V. In this self-bias mode of operation, the difference between the input and output voltages of the internal

LDO are reduced, and therefore the total efficiency of the LM46000 is improved. These efficiency gains are more

evident during light load operation. During this mode of operation, the LM46000 operates with a minimum

quiescent current of 24 µA (typical). See VCC, UVLO, and BIAS for more details.

LM46000PWP Datasheet(PDF) 24 Page - Texas Instruments