SC446TETRT Semtech, SC446TETRT Datasheet - Page 16

• Manufacturer Part Number: SC446TETRT
• Description: IC LED DRVR WHT BCKLGT TSSOP-16
• Manufacturer: Semtech
• Type: Backlight, White LEDr

Specifications of SC446TETRT

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 3
• Internal Driver: Yes
• Type - Primary: Backlight
• Frequency: 700kHz
• Voltage - Supply: 4.5 V ~ 27 V
• Voltage - Output: 36V
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
• Current - Output / Channel: 100mA
• Internal Switch(s): Yes
• Efficiency: 90%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Other names: SC446TETR

SC446
Applications Information (continued)
Layout Guidelines
The SC446 contains a boost converter and the placements
of the power components outside the SC446 should fol-
low the layout guidelines of a general boost converter.
The evaluation application circuit on page 17 will be used
as an example. C2 and C3 are input decoupling capacitor
for SC446 VIN pin and main power input. C2,C3 should be
placed as close as possible to the VIN pin to achieve the
best decoupling performance.
To minimize the switching noise, The switching loop
formed by input decoupling capacitors, internal switch,
output Schottky diode and output capacitors must be
minimized. The LED current programming resistor(R6),
compensation network (R9,C5,C7) and soft start capaci-
tor (C6) should be placed as close as possible to SC446.
The C14~C17 are decoupling capacitors for LED cur-
rent source which prevent IO pins from noise influence.
C14~C17 should be placed close to each corresponding
IO pin.
Use an isolated local AGND plane underneath the con-
troller and tie it to the negative side of output capacitor
through R14 for better noise immunity.
© 2010 Semtech Corporation
16
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