EN

BP

VOUT

7 20 µs

VIN

8 30 µs

VCON

R1 = 100 k:

C1 = 1.7 pF

C2 = 9 pF

LM3243

SNVS782C – OCTOBER 2010 – REVISED AUGUST 2015

www.ti.com

Figure 20. VCON Pin Equivalent CRC Circuit

8.2.2.4 EN Input Control

Use the system controller to drive the EN HIGH or LOW with a comparator, Schmitt trigger or logic gate. Set EN

= HIGH (> 1.2 V) for normal operation and LOW (< 0.5 V) for shutdown mode to reduce current consumption to

0.02-µA (typical) current.

8.2.2.5 Start-Up

V. Next, EN should go HIGH (> 1.2 V). Finally, VCON should be set to a value that corresponds to the required

start-up time and behavior of the output voltage, the LM3243 will always start up in PWM mode (even when

MODE = HIGH and output load current

≤ 75 mA), then seamlessly transition into PFM mode.

Figure 21. Start-Up Sequence and Conditions

18

Submit Documentation Feedback

Copyright © 2010–2015, Texas Instruments Incorporated

Product Folder Links: LM3243