LMR62014_15 Datasheet, PDF (10/22 Pages) Texas Instruments – LMR62014 SIMPLE SWITCHER® 20Vout, 1.4A Step-Up Voltage Regulator in SOT-23

LMR62014
SNVS735B – OCTOBER 2011 – REVISED APRIL 2013
www.ti.com
FEED-FORWARD COMPENSATION
Although internally compensated, the feed-forward capacitor Cf is required for stability (see Basic Application
Circuit). Adding this capacitor puts a zero in the loop response of the converter. The recommended frequency for
the zero fz should be approximately 6 kHz. Cf can be calculated using the formula:
Cf = 1 / (2 X π X R1 X fz)
(1)
SELECTING DIODES
The external diode used in the typical application should be a Schottky diode.The diode must be rated to handle
the maximum output voltage and load current. A 20V diode such as the MBR0520 is recommended.
The MBR05XX series of diodes are designed to handle a maximum average current of 0.5A. For applications
exceeding 0.5A average, a Toshiba CRS08 can be used.
LAYOUT HINTS
High frequency switching regulators require very careful layout of components in order to get stable operation
and low noise. All components must be as close as possible to the LMR62014 device. It is recommended that a
4-layer PCB be used so that internal ground planes are available.
As an example, a recommended layout of components is shown:
Figure 18. Recommended PCB Component Layout
Some additional guidelines to be observed:
1. Keep the path between L1, D1, and C2 extremely short. Parasitic trace inductance in series with D1 and C2
will increase noise and ringing.
2. The feedback components R1, R2 and CF must be kept close to the FB pin of U1 to prevent noise injection
on the FB pin trace.
3. If internal ground planes are available (recommended) use vias to connect directly to ground at pin 2 of U1,
as well as the negative sides of capacitors C1 and C2.
10
Submit Documentation Feedback
Product Folder Links: LMR62014
Copyright © 2011–2013, Texas Instruments Incorporated