Datasheet Texas Instruments TPS62270DRVTG4 — 数据表

TPS62270, TPS62272
TPS62273
www.ti.com . SLVS799C – NOVEMBER 2007 – REVISED JANUARY 2009 2.25 MHz 400-mA Step Down Converter With Selectable VOUT
FEATURES 1 High Efficiency Step Down Converter Output Current up to 400 mA VIN Range From 2V to 6V for Li-Ion Batteries
With Extended Voltage Range 2.25 MHz Fixed Frequency Operation Pin-Selectable Fixed Output Voltage Power Save Mode for Highest Efficiency Automatic transition between PFM and PWM
Mode Voltage Positioning in PFM Mode Typical 15-ВµA Quiescent Current 100% Duty Cycle for Lowest Dropout Available in 2Г—2Г—0,8 mm SON Package Allows 4.5V. The input capacitor can be increased without any limit for better
input voltage filtering. Take care when using only small ceramic input capacitors. When a ceramic capacitor is
used at the input and the power is being supplied through long wires, such as from a wall adapter, a load step at
the output or VIN step on the input can induce ringing at the VIN pin. This ringing can couple to the output and
be mistaken as loop instability or could even damage the part by exceeding the maximum ratings.
Table 3. List of Capacitors 16 CAPACITANCE TYPE SIZE mm3 SUPPLIER 4.7 µF GRM188R60J475K 0603: 1.6 × 0.8 × 0.8 mm3 Murata 10 µF GRM188R60J106M69D 0603: 1.6 × 0.8 × 0.8 mm3 Murata Submit Documentation Feedback Copyright © 2007–2009, Texas Instruments Incorporated Product Folder Link(s): TPS62270 TPS62272 TPS62273 TPS62270, TPS62272
TPS62273
www.ti.com . SLVS799C – NOVEMBER 2007 – REVISED JANUARY 2009 LAYOUT CONSIDERATIONS
As for all switching power supplies, the layout is an important step in the design. Proper function of the device
demands careful attention to PCB layout. Care must be taken in board layout to get the specified performance. If
the layout is not carefully done, the regulator could show poor line and/or load regulation, stability issues as well
as EMI problems. It is critical to provide a low inductance, impedance ground path. Therefore, use wide and
short traces for the main current paths. The input capacitor should be placed as close as possible to the IC pins
as well as the inductor and output capacitor.
Connect the GND Pin of the device to the PowerPadв„ў of the PCB and use this pad as a star point. Use a
common Power GND node and a different node for the Signal GND to minimize the effects of ground noise.
Connect these ground nodes together to the PowerPadв„ў (star point) underneath the IC. Keep the common path
to the GND PIN, which returns the small signal components and the high current of the output capacitors as …