Microchip Technology ARD00386 数据表
MCP1640 12V/50 mA Two Cells Input Boost Converter Reference Design
DS51999A-page 16
© 2011 Microchip Technology Inc.
The board has several test points that help engineers analyze the switch node’s
waveforms or MCP1640’s output:
waveforms or MCP1640’s output:
• The high-voltage switch node test point (SWH).
• The test point of the MCP1640 device’s switch node (SWL).
• VO test point shows the MCP1640 device’s V
OUT
pin (this output is unregulated).
The difference between SWH and SWL signals is their amplitude. For 12V output, the
amplitude of SWL is approximately 5V, while SWH shows the sum of MCP1640's SW
node (SWL signal) and external n-channel MOS voltage.
amplitude of SWL is approximately 5V, while SWH shows the sum of MCP1640's SW
node (SWL signal) and external n-channel MOS voltage.
Figures
show the Discontinuous (25 mA load for 2.4V V
IN
) and Continuous
mode waveforms (60 mA load at 2.4V V
IN
, where the inductor peak current is close to
the maximum input peak current limit of the MCP1640 device, 800 mA). Once the
800 mA limit is reached, V
800 mA limit is reached, V
OUT
value is decreasing (goes out of regulation).
The mean
value of the inductor current (I
L
) is equal for a boost converter with the input current
(except the current consumption of MCP1640).
FIGURE 2-4:
MCP1640 12V/50 mA Two Cells Input Boost Converter
Reference Design Test Points (SWH, SWL), Inductor (I_L) and Load Current (I_OUT)
Waveforms for 25 mA Load and 2.4V Input in Discontinuous Mode.
Waveforms for 25 mA Load and 2.4V Input in Discontinuous Mode.