LYT1402-1604
The bypass supply capacitor C5 should be placed directly across
BYPASS pin and SOURCE pin of U1 for effective noise decoupling.
PCB Layout Considerations
In Figure 6, the EMI filter components should be located close
together to improve filter effectiveness. Place the EMI filter compo-
nents C1 and L1 as far away as possible from any switching nodes on
the circuit board especially U1 drain node, output diode (D1) and the
transformer (T3).
As shown in Figure 6, minimize the loop areas of the following
switching circuit elements to lessen the creation of EMI.
• Loop area formed by the transformer winding (T3), free-wheeling
rectifier diode (D1) and output capacitor (C6).
• Loop area formed by input capacitor (C4), U1 internal MOSFET,
free-wheeling rectifier diode (D1) and sense resistor (R5).
Care should be taken in placing the components on the layout that
are used for processing input signals for the feedback loop that any
high frequency noise coupled to the signal pins of U1 may affect
proper system operation. The critical components in RDK-464 are R4,
R5, R6, R7 and C5. It is highly recommended that these components
be placed very close to the pins of U1 (to minimize long traces which
could serve as antenna) and far away as much as possible from any
high-voltage and high current nodes in the circuit board to avoid
noise coupling.
LYTSwitch-1 Low-Side Configuration
In Figure 8, LYTSwitch-1 employs low-side Buck configuration and the
ground potential SOURCE pins are used for heat sinking. This allows
the designer to maximize the copper area for good thermal manage-
ment but, without having the risk of increased EMI.
ꢀꢁꢂꢃꢄꢅꢁꢆꢇꢃꢄꢈꢆ ꢉꢊꢋ
ꢌꢊvꢊꢍeꢎ Reꢏꢊꢏꢐꢑꢎꢏ R7 ꢒ Rꢓ
ꢂꢭꢃꢚꢮꢊꢐꢨꢝꢡ1
ꢀꢔꢕꢊꢖꢊꢗeꢍ ꢇꢑꢘꢘeꢎ
ꢤꢁ1ꢥ
ꢙeꢔꢐ ꢚꢊꢋꢛ
ꢀꢁꢂꢃT
ꢄꢃTꢂꢃT
ꢃꢊꢜꢝꢐ ꢂꢑꢑꢘ ꢞꢎeꢔ ꢅꢑꢎꢖeꢍ ꢟꢠ ꢄꢋꢘꢧꢐ
ꢇꢔꢘꢔꢨꢊꢐꢑꢎ ꢤꢇꢓꢥꢦ ꢅꢎeeꢡꢢꢝeeꢣꢊꢋꢜ ꢌꢊꢑꢍe ꢤꢌ1ꢥꢦ
ꢈꢧꢐꢘꢧꢐ ꢇꢔꢘꢔꢨꢊꢐꢑꢎ ꢤꢇ6ꢥꢦ ꢀꢈꢚꢅꢫꢃ ꢤꢁ1ꢥꢦ
ꢚeꢋꢏe Reꢏꢊꢏꢐꢑꢎ ꢤRꢬꢥ Rꢪ ꢒ ꢇꢓ
Bꢭꢉꢞꢚꢚ ꢉꢊꢋ
ꢇꢔꢘꢔꢨꢊꢐꢑꢎ ꢇꢬ
ꢃꢊꢜꢝꢐ ꢂꢑꢑꢘ ꢞꢎeꢔ ꢅꢑꢎꢖeꢍ ꢟꢠ ꢐꢝe
ꢅꢎeeꢡꢢꢝeeꢣꢊꢋꢜ ꢌꢊꢑꢍe ꢤꢌ1ꢥꢦ ꢈꢧꢐꢘꢧꢐ
ꢇꢔꢘꢔꢨꢊꢐꢑꢎ ꢤꢇ6ꢥꢦ ꢄꢋꢍꢧꢨꢐꢑꢎ ꢤꢃꢩꢥ
ꢉꢄꢡ7ꢪꢯꢯꢡ061016
Rꢪ ꢒ ꢇꢓ
Figure 6. Design Example RDK-464 PCB Layout Showing the Critical Loop Areas with LYTSwitch-1 in High-Side Buck Configuration.
120 ꢆꢇ 1ꢈ0 ꢉꢊ
ꢆꢋ
R1
BR1
B10ꢈꢂꢙ
1000 ꢊ
10 ꢕ
Ω
1/ꢅ ꢐ
ꢓ1
1 ꢑ
L
ꢋ1
ꢔ.7 ꢍꢎ
Rꢔ
ꢌ00 ꢕ
1/ꢅ ꢐ
ꢒꢌ
1ꢄ0 ꢗꢓ
ꢔꢄ0 ꢊ
ꢒꢖ
6ꢅ µꢓ
160 ꢊ
ꢆ1
ꢇꢈ1ꢉ
600 ꢊ
Rꢊ1
ꢌ7ꢄ ꢊꢑꢒ
Ω
ꢒ1
100 ꢗꢓ
ꢖ0ꢄ ꢊ
1ꢍ0 - ꢎ00
ꢆꢊꢏ
R7
LYTꢃꢑꢒꢓꢔꢕ-1
ꢌ.ꢌ
Ω
ꢋꢚꢛ160ꢔꢆ
1ꢏ
1/ꢅ ꢐ
ꢌ
ꢒꢄ
Rꢖ
ꢌ00 ꢕ
1ꢏ
ꢁꢂ
ꢀ
ꢔ.7 µꢓ
Ω
ꢐTꢌ
16 ꢊ
ꢃ
ꢋꢌ
ꢆ-
R6
Rꢄ
6.ꢅ1 ꢕ
1ꢏ
1.ꢄ ꢍꢎ
ꢒꢔ
ꢂꢅ
ꢄ
0.ꢄ1
1ꢏ
Ω
Ω
ꢀꢁꢂ7ꢃꢄꢃꢂ0ꢄ1ꢅ16
100 ꢘꢓ
1000 ꢊ
1/ꢅ ꢐ
1/16 ꢐ
Rꢌ
ꢌ00 ꢕ
Ω
1ꢏ
1/ꢅ ꢐ
Figure 7. Schematic from DER-548 a 20 W, 120 V-170 mA Non-isolated LED Driver for Tube with High-line Input Range of 190 – 300 VAC using LYT1604D.
5
Rev. B 07/16
www.power.com
POWERINT [ Power Integrations ]
