LM2757_14 Datasheet, PDF (13/20 Pages) Texas Instruments – Switched Capacitor Boost Regulator with High Impedance Output in Shutdown

LM2757
www.ti.com
SNVS536D – OCTOBER 2007 – REVISED AUGUST 2009
Table 1. LM2757 Performance with Different Capacitor Configurations ⁽¹⁾ (continued)
Capacitor
Configuration
(V_IN = 3.6V)
C_IN = 0.68µF,
C_OUT = 1µF,
C₁, C₂ = 0.47µF
C_IN = 0.68µF,
C_OUT = 0.47µF,
C₁, C₂ = 0.47µF
C_IN = 0.68µF,
C_OUT = 0.47µF,
C₁, C₂ = 0.22µF
Typical
5.0V,200mA
Output
Ripple
32mV
51mV
53mV
Typical
4.5V,100mA
Output
Ripple
11mV
15mV
18mV
Typical
4.1V,100mA
Output
Ripple
11mV
15mV
18mV
Layout Guidelines
Proper board layout will help to ensure optimal performance of the LM2757 circuit. The following guidelines are
recommended:
• Place capacitors as close to the LM2757 as possible, and preferably on the same side of the board as the IC.
• Use short, wide traces to connect the external capacitors to the LM2757 to minimize trace resistance and
inductance.
• Use a low resistance connection between ground and the GND pin of the LM2757. Using wide traces and/or
multiple vias to connect GND to a ground plane on the board is most advantageous.
Application Circuits
USB OTG / Mobile HDMI POWER SUPPLY
V_BAT (System Voltage)
Dual Role
Application
Processor
EN (V_M1)
V_M0
LM2757 (Host
Mode V_BUS
Power)
V_OUT / V_BUS (5V)
USB OTG
Transceiver
USB Connector
V_BUS
ID
D+
D-
GND
The 5V output mode will normally be used for the USB OTG / Mobile HDMI application. Therefore the LM2757
can be enabled/disabled by applying a logic signal on only the M1 pin while grounding the M0 pin. Depending on
the USB/HDMI mode of the application, the LM2757 can be enabled to drive the power bus line (Host), or
disabled to put its output in high impedance allowing an external supply to drive the bus line (Slave). In addition
to the high impedance-backdrive protection, the output current limit protection is 250mA (typ.), well within the
USB OTG and HDMI requirements.
Copyright © 2007–2009, Texas Instruments Incorporated
Product Folder Links: LM2757
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