NCP5005GEVB ON Semiconductor, NCP5005GEVB Datasheet - Page 6

• Manufacturer Part Number: NCP5005GEVB
• Description: EVAL BOARD FOR NCP5005G
• Manufacturer: ON Semiconductor

Specifications of NCP5005GEVB

• Design Resources: NCP5005 EVB BOM NCP5005GEVB Gerber Files NCP5005 EVB Schematic
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 22V
• Voltage - Input: 3.6V
• Utilized Ic / Part: NCP5005
• Core Chip: NCP5005
• Topology: Boost
• No. Of Outputs: 1
• Development Tool Type: Hardware - Eval/Demo Board
• Leaded Process Compatible: Yes
• Mcu Supported Families: NCP5005SNT1G
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Current - Output / Channel: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: NCP5005G
• Other names: NCP5005GEVBOS

Discontinuous Mode of Operation Analysis
large peak current takes place in the inductor as depicted in
Figure 6. The PWM mode is prone to such a discontinuous
cycle. The output voltage is largely different, in comparison
with the NCP5007, as one expects from a discontinuous
mode of operation. The main consequence is the large
oscillations developed when the transfer of the current
between the inductor and the load is completed. Of course,
internal circuit can be implemented to avoid such oscillation
(so-called ring killer), but all ICs might not have such
features. The oscillations are no longer the only
consequence of the Schottky diode, but come from the main
inductor (22 mH) associated with the stray capacitances.
Assuming we have a 30 pF stray capacitance (the Schottky
When a chip operates in a fully discontinuous mode, a
Figure 6. Typical PWM Normal Operation
http://onsemi.com
AND8172/D
6
diode as a minimum parasitic capacitance since the reverse
voltage is maximum), the frequency is 6.2 MHz, yielding a
161 ns period. The calculated values are well within the
evaluation tests carried out with a PWM based white LED
driver used as a reference (Figure 6, top trace).
during this period:
inductor and this element is prone to radiate most of this
energy out of the core, unless a shielding magnetic core is
used.
Ej + 1
Ej + 1
At this point, one can derive the level of energy radiated
Although such a level is low, is it generated by the main
2
2
* L * I 2
* 22 * 10 -6 * 0.04 2 + 4.4 nJ
(I = level of the current during the oscillation
first order only)
(eq. 5)