MCP1630RD-SALED Microchip Technology, MCP1630RD-SALED Datasheet - Page 12

• Manufacturer Part Number: MCP1630RD-SALED
• Description: Power Management IC Development Tools MCP1630 Sepic Automotive LED Drvr
• Manufacturer: Microchip Technology
• Type: DC/DC Converters, Regulators & Controllersr

Specifications of MCP1630RD-SALED

• Rohs: yes
• Product: Reference Designs
• Tool Is For Evaluation Of: MCP1630
• Input Voltage: 9 V to 16 V
• Output Voltage: 55 V
• Output Current: 350 mA

MCP1630 Sepic Automotive LED Driver Reference Design
1.5
1.6
DS51955A-page 12
FUNCTIONAL DESCRIPTION
WHAT THE MCP1630 SEPIC AUTOMOTIVE LED DRIVER REFERENCE
DESIGN KIT INCLUDES
The MCP1630 device provides all the analog functions necessary to implement a Peak
Current Mode PWM DC-DC Converter. The power train is based on the Single-Ended
Primary Inductor Converter (SEPIC) topology. This topology offers the buck-boost
functionality and also has non-pulsating input current.
The converter provides adjustable constant current at the output, necessary to drive
high-power LED applications.
The MCP1630 PWM controller requires an external clock for operation. This clock is
provided by an external 8-bit microcontroller, PIC12F683. The PWM frequency and the
maximum duty cycle are set by this clock.
The output (load) current is sensed with a 0.5Ω shunt resistor (R17 and R18). The
voltage across this shunt resistor is compared with the reference voltage by the
MCP1630 device’s PWM controller.
The reference voltage for the MCP1630 device is also provided by PIC12F683, at the
V
produced by the PIC
and R3 voltage dividers. The duty cycle of the PWM signal is adjusted in eight steps.
The output current is calculated with Equation 1-1:
EQUATION 1-1:
Because the operating duty cycle is bigger than 50%, a slope compensation circuit is
required to avoid subharmonic oscillations that occur in Peak Current mode controllers.
A ramp generator is constructed with Q1 and the associated components. The ramp is
then summed with the inductor current, measured across R9 and R10 resistors.
A 100V V
MOSFET driver drives the gate of this transistor. This is necessary because the
high-voltage transistors usually have high gate charge and also require at least 7V for
gate-to-source voltage.
The MCP1630 Sepic Automotive LED Driver Reference Design includes:
• MCP1630 Sepic Automotive LED Driver Reference Design (102-00323)
• Important Information Sheet
REF
Note:
pin (Pin 8). R4, R3 and C2 form a low-pass filter that smooths the PWM signal
DS
The MCP1416 MOSFET driver must be protected against input voltage
surges. This protection is ensured by R6 and D1.
MOSFET transistor is also used in this application. The MCP1416
Where:
®
microcontroller. The maximum output current is set by the R4
V
I
OUTmax
REFmax
I
OUT
=
=
=
⎛
⎝
178mV
---------------- -
V
----------- -
-------------------- -
R3
0.5
0.5
REF
R3
+
R4
=
⎞
⎠
357mA
×
5V
© 2011 Microchip Technology Inc.
=
178
mV