MCP16321/2 24V Input, 1A/2A Output, High Efficiency Synchronous Buck Regulator with Power Good Indication Features Description • • • • • The MCP16321/2 is a highly integrated, high-efficiency, fixed frequency, synchronous step-down DC-DC converter in a 16-pin QFN package that operates from input voltages up to 24V. Integrated features include a high-side and low-side N-Channel switch, fixed frequency Peak Current Mode Control, internal compensation, peak current limit, VOUT overvoltage protection and overtemperature protection. Minimal external components are necessary to develop a complete synchronous step-down DC-DC converter power supply. • • • • • • • • • • • • • • • Up to 95% Typical Efficiency Input Voltage Range: 6.0V to 24V 1A Output Current (MCP16321) 2A Output Current (MCP16322) Fixed Output Voltages: 0.9V, 1.5V, 1.8V, 2.5V, 3.3V, 5V with 2% Output Voltage Accuracy Adjustable Version Output Voltage Range: 0.9V to 5V with 1.5% Reference Voltage Accuracy Integrated N-Channel High-Side Switch: 180 mΩ Integrated N-Channel Low-Side Switch: 120 mΩ 1 MHz Fixed Frequency Low Device Shutdown Current Peak Current Mode Control Internal Compensation Stable with Ceramic Capacitors Internal Soft-Start Cycle-by-Cycle Peak Current Limit Undervoltage Lockout (UVLO): 5.75V Overtemperature Protection VOUT Overvoltage Protection VOUT Voltage Supervisor Reported at the PG Pin Available Package: QFN-16 (3x3 mm) Applications • • • • • • • • • • • • PIC®/dsPIC® Microcontroller Bias Supply 12V Industrial Input DC-DC Conversion Set-Top Boxes DSL Cable Modems Automotive Wall Cube Regulation SLA Battery Powered Devices AC-DC Digital Control Power Source Power Meters Consumer Medical and Health Care Distributed Power Supplies © 2011 Microchip Technology Inc. High converter efficiency is achieved by integrating a high-speed, current limited, low resistance, high-side N-Channel MOSFET, as well as a high-speed, low resistance, low-side N-Channel MOSFET and associated drive circuitry. High switching frequency minimizes the size of the inductor and output capacitor, resulting in a small solution size. The MCP16321/2 device can supply 1A/2A of continuous current while regulating the output voltage from 0.9V to 5V. A high-performance peak current mode architecture keeps the output voltage tightly regulated, even during input voltage steps and output current transient conditions that are common in power supplies. The regulator can be turned on and off with a logic level signal applied to the EN input. The EN input is internally pulled up to a 4.2V reference and is rated for a maximum of 6V. With EN low, typically 5 µA of current is consumed from the input, making the part ideal for power shedding and load distribution applications. The PG output is an open drain output pin used to interface with other components of the system, and can be pulled up to a maximum of 6V. The output voltage can either be fixed at output voltages of 0.9V, 1.5V, 1.8V, 2.5V, 3.3V, 5V or adjustable using an external resistor divider. The MCP16321/2 is offered in a 3x3 QFN-16 surface mount package. DS22285A-page 1 MCP16321/2 Package Type SW PGND PGND SW MCP16321/2 3x3 QFN* 16 15 14 13 12 SW SW 1 VIN 2 11 VIN EP 17 VIN 3 10 BOOST 9 EN 5 6 7 8 FB NC NC PG SGND 4 * Includes Exposed Thermal Pad (EP); see Table 3-1. Typical Applications Typical Application with Adjustable Output Voltage CBOOST 22 nF L1 4.7 μH BOOST VIN 6.0V to 24V SW MCP16321/2 VIN CIN 2x10 μF VOUT 4.2V @ 1A/2A EN SGND 36.5 k VFB COUT 2x22 μF VOUT 10 k 10 k PG PGND Typical Application with Fixed Output Voltage CBOOST 22 nF L1 4.7 μH BOOST VIN 6.0V to 24V SW MCP16321/2 VIN CIN 2x10 μF EN SGND DS22285A-page 2 VOUT 3.3V @ 1A/2A COUT 2x22 μF VFB VOUT 10 k PG PGND © 2011 Microchip Technology Inc. MCP16321/2 1.0 † Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings† VIN .................................................................... -0.3V to 26.4V SW ...................................................................... -1V to 26.4V BOOST – GND ........................................... -0.3V to (VIN+6V) EN,VFB, PG Voltage.............................................. -0.3V to 6V Continuous Total Power Dissipation ....................................... ...................................................See Thermal Characteristics Storage Temperature ....................................-65°C to +150°C Operating Junction Temperature...................-40°C to +125°C ESD Protection On All Pins: HBM ......................................................................... 3 kV MM ..........................................................................200V DC CHARACTERISTICS Electrical Characteristics: Unless otherwise indicated, TA = +25°C, VIN = 12V, VOUT = 3.3V, IOUT = 300 mA, L = 4.7 µH, COUT = 2x22 µF, CIN = 2x10 µF. Boldface specifications apply over the TJ range of -40°C to +125°C. Parameters Sym Min Typ Max Input Voltage VIN Quiescent Current (Switching) IQ Quiescent Current (Non-Switching) Quiescent Current Shutdown Units Conditions 6.0 — 24 V — 5.2 — mA IOUT = 0 mA IQ — 2.3 — mA Closed Loop in Overvoltage IOUT = 0 mA IQ — 5 10 µA EN = 0 Undervoltage Lockout Start UVLOSTRT 5.5 5.75 6.0 V VIN Rising Undervoltage Lockout Hysteresis UVLOHYS — 0.65 — V Non-Switching Maximum Output Current MCP16321 IOUT 1 — — A VIN = 6V to 24V Maximum Output Current MCP16322 IOUT 2 — — A VIN = 6V to 24V Output Voltage Adjust Range VOUT 0.9 — 5.0 V Output Voltage Tolerance in PWM Mode VOUT-PWM VOUT - 2% VOUT VOUT + 2% V IOUT = 1A Output Voltage Tolerance in PFM Mode VOUT-PFM VOUT - 1% VOUT + 1% VOUT + 3.5% V IOUT = 0A VIN Supply Voltage VIN Undervoltage Lockout Output Characteristics Feedback Voltage VFB 0.886 0.9 0.914 V Feedback Reference Tolerance VFB-TOL -1.5 — 1.5 % PFM Mode Feedback Comparator Threshold VFB-PFM — VOUT + 1% — V IFB — 100 — nA Feedback Input Bias Current Note 1: Regulator SW pin is forced off for 240 ns every 8 cycles to ensure the BOOST cap is replenished. © 2011 Microchip Technology Inc. DS22285A-page 3 MCP16321/2 DC CHARACTERISTICS (CONTINUED) Electrical Characteristics: Unless otherwise indicated, TA = +25°C, VIN = 12V, VOUT = 3.3V, IOUT = 300 mA, L = 4.7 µH, COUT = 2x22 µF, CIN = 2x10 µF. Boldface specifications apply over the TJ range of -40°C to +125°C. Parameters Sym Min Typ Max Units VFB-PFM — VOUT + 1% — V VIH 2.2 — — V EN Input Logic Low VIL — — 0.8 V EN Input Hysteresis VEN-HYST — 480 — mV IENLK — 3.5 — µA VEN = 5V — -1.5 — µA VEN = 0V tSS — 4 — ms Switching Frequency fSW 0.9 1 1.1 Maximum Duty Cycle DCMAX 95 97 99 PFM Mode Feedback Conditions EN Input Characteristics EN Input Logic High EN Input Leakage Current Soft-Start Time Switching Characteristics Minimum Duty Cycle MHz Open Loop VFB Low % Open Loop VFB Low Note 1 — 7 — % NMOS Low-Side Switch On Resistance Low-Side RDS(ON) — 120 — mΩ NMOS High-Side Switch On Resistance High-Side RDS(ON) — 180 — mΩ IN(MAX) 1.4 1.8 2.4 A MCP16321 2.4 2.8 3.4 A MCP16322 NMOS High-Side Switch Current Limit PG Output Characteristics PG Low-level Output Voltage PGIL — — 0.01 V IPG = -0.3 mA PG High-Level Output Leakage Current IPGLK — 0.5 — µA VPG = 5V ms PG Release Timer tPG — 10 — VOUT-UV 91% VOUT 93% VOUT 95% VOUT VOUT Undervoltage Hysteresis VOUT-UV_HYST — 1.5% VOUT — VOUT Overvoltage Threshold VOUT-OV — 103% VOUT — VOUT Overvoltage Hysteresis VOUT-OV_HYST — 1% VOUT — TSD — 170 — °C TSDHYS — 10 — °C VOUT Undervoltage Threshold Thermal Characteristics Thermal Shutdown Die Temperature Die Temperature Hysteresis Note 1: Regulator SW pin is forced off for 240 ns every 8 cycles to ensure the BOOST cap is replenished. DS22285A-page 4 © 2011 Microchip Technology Inc. MCP16321/2 TABLE 1-1: TEMPERATURE CHARACTERISTICS Electrical Characteristics Parameters Sym Min Typ Max Units Operating Junction Temperature Range TJ -40 — 125 °C Storage Temperature Range TA -65 — 150 °C Maximum Junction Temperature TJ — — 150 °C θJA — 38.5 — Conditions Temperature Ranges Steady State Transient Package Thermal Resistances Thermal Resistance, 16L 3x3-QFN Note 1: °C/W Note 1 2 Measured using a 4-layer FR4 Printed Circuit Board with a 13.5 in , 1 oz internal copper ground plane. © 2011 Microchip Technology Inc. DS22285A-page 5 MCP16321/2 NOTES: DS22285A-page 6 © 2011 Microchip Technology Inc. MCP16321/2 2.0 TYPICAL PERFORMANCE CURVES The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. Note: 100 95 90 85 80 75 70 65 60 55 50 100 VIN = 6V VIN = 12V VIN = 18V VIN = 24V VOUT = 5V 0.8 1.2 IOUT (A) 1.6 VOUT = 1.8V 5V VOUT Efficiency vs. IOUT. 0 VIN = 6V 80 VIN = 12V 75 VIN = 18V 70 VOUT = 3.3V 65 60 VIN = 24V 55 50 0 0.4 0.8 1.2 IOUT (A) 1.6 90 85 80 75 70 65 60 55 50 45 40 0.8 1.2 IOUT (A) 1.6 2 1.8V VOUT Efficiency vs. VIN = 6V VIN = 12V VIN = 18V VOUT = 1.5V 0 2 3.3V VOUT Efficiency vs. FIGURE 2-2: IOUT. 0.4 FIGURE 2-4: IOUT. Efficiency (%) Efficiency (%) VIN = 18V 60 2.0 85 0.4 0.8 1.2 IOUT (A) 1.6 2 1.5V VOUT Efficiency vs. FIGURE 2-5: IOUT. 100 100 VIN = 6V 90 Efficiency (%) 90 Efficiency (%) VIN = 12V 70 40 0.4 FIGURE 2-1: 90 80 50 0.0 95 VIN = 6V 90 Efficiency (%) Efficiency (%) Note: Unless otherwise indicated, VIN = 12V, EN = Floating (Internally pulled up), CIN = 20 µF, COUT = 2x22 µF, L = 4.7 µH (XAL6060-472MEB), ILOAD = 200 mA, TA = +25°C. MCP16321 maximum output current = 1A. 80 VIN = 12V 70 VIN = 18V 60 VIN = 6V 80 70 VIN = 8V 60 VOUT = 0.9V VOUT = 2.5V 50 VIN = 24V 50 40 VIN = 10V 40 0 FIGURE 2-3: IOUT. 0.4 0.8 1.2 IOUT (A) 1.6 2 2.5V VOUT Efficiency vs. © 2011 Microchip Technology Inc. 0 FIGURE 2-6: IOUT. 0.4 0.8 1.2 IOUT (A) 1.6 2 0.9V VOUT Efficiency vs. DS22285A-page 7 MCP16321/2 Note: Unless otherwise indicated, VIN = 12V, EN = Floating (Internally pulled up), CIN = 20 µF, COUT = 2x22 µF, L = 4.7 µH (XAL6060-472MEB), ILOAD = 200 mA, TA = +25°C. MCP16321 maximum output current = 1A. 5.04 VOUT = 5V 5.03 VOUT (V) 5.01 VOUT (V) VIN = 6V 5.02 VIN = 12V 5 VIN = 18V VIN = 24V 4.99 4.98 0 0.4 FIGURE 2-7: 0.8 1.2 IOUT (A) 1.6 1.808 1.807 1.806 1.805 1.804 1.803 1.802 1.801 1.8 1.799 1.798 2 5V VOUT vs. IOUT. VOUT =1.8V VIN = 6V VIN = 12V VIN = 18V 0 0.4 FIGURE 2-10: 3.32 0.8 1.2 IOUT (A) 1.6 2 1.8V VOUT vs. IOUT. 1.505 VOUT =3.3V VOUT =1.5V 1.504 3.315 VIN = 6V 3.305 VOUT (V) VOUT (V) 1.503 3.31 VIN = 12V VIN = 6V 1.502 1.501 VIN = 12V 1.5 3.3 VIN = 24V 3.295 0 0.4 1.498 1.6 2 3.3V VOUT vs. IOUT. 2.515 2.513 2.511 2.509 2.507 2.505 2.503 2.501 2.499 2.497 2.495 0 0.4 FIGURE 2-11: 0.8 1.2 IOUT (A) 1.6 2 1.5V VOUT vs. IOUT. 0.904 VOUT =0.9V VOUT =2.5V 0.903 0.902 VIN = 6V VOUT (V) VOUT (V) FIGURE 2-8: 0.8 1.2 IOUT (A) VIN = 16V 1.499 VIN = 18V VIN = 12V VIN = 6V 0.901 0.9 VIN = 8V 0.899 VIN = 10V VIN = 24V 0.898 VIN = 18V 0.897 0 FIGURE 2-9: DS22285A-page 8 0.4 0.8 1.2 IOUT (A) 1.6 2.5V VOUT vs. IOUT. 2 0 FIGURE 2-12: 0.4 0.8 1.2 IOUT (A) 1.6 2 0.9V VOUT vs. IOUT. © 2011 Microchip Technology Inc. MCP16321/2 Note: Unless otherwise indicated, VIN = 12V, EN = Floating (Internally pulled up), CIN = 20 µF, COUT = 2x22 µF, L = 4.7 µH (XAL6060-472MEB), ILOAD = 200 mA, TA = +25°C. MCP16321 maximum output current = 1A. 5.02 1.804 VOUT = 1.8V VOUT = 5V 5.015 1.803 1.802 VOUT (V) VOUT (V) 5.01 5.005 1.801 IOUT = 1A 5 1.8 4.995 IOUT = 2A 4.99 IOUT = 1A 1.799 IOUT = 2A 1.798 4.985 6 8 10 FIGURE 2-13: 12 14 16 VIN (V) 18 20 22 6 24 5V VOUT vs VIN. 12 VIN (V) 14 16 18 1.8V VOUT vs VIN. 1.503 VOUT = 3.3V 3.308 VOUT = 1.5V 1.5025 1.502 3.306 IOUT = 2A 1.5015 3.304 VIN (V) VOUT (V) 10 FIGURE 2-16: 3.31 3.302 IOUT = 1A 3.3 1.501 1.5005 1.5 3.298 IOUT = 1A 1.4995 3.296 1.499 IOUT = 2A 1.4985 3.294 6 8 10 FIGURE 2-14: 12 14 16 VIN (V) 18 20 22 3.3V VOUT vs VIN. 2.506 2.505 2.504 2.503 2.502 2.501 2.5 2.499 2.498 2.497 2.496 6 24 8 10 12 VOUT (V) FIGURE 2-17: 14 16 1.5V VOUT vs VIN. 0.9012 VOUT = 2.5V VOUT = 0.9V 0.901 0.9008 VOUT (V) VOUT (V) 8 IOUT = 1A 0.9006 0.9004 0.9002 IOUT = 1A 0.9 0.8998 IOUT = 2A 0.8996 IOUT = 2A 0.8994 6 8 FIGURE 2-15: 10 12 14 16 VIN (V) 18 20 2.5V VOUT vs VIN. © 2011 Microchip Technology Inc. 22 24 6 FIGURE 2-18: 7 8 VIN (V) 9 10 0.9V VOUT vs VIN. DS22285A-page 9 MCP16321/2 Note: Unless otherwise indicated, VIN = 12V, EN = Floating (Internally pulled up), CIN = 20 µF, COUT = 2x22 µF, L = 4.7 µH (XAL6060-472MEB), ILOAD = 200 mA, TA = +25°C. MCP16321 maximum output current = 1A. 1020 Oscillator Frequency (kHz) Shudown Current (µA) 8 7 6 5 4 3 2 1 0 10 14 VIN (V) 18 1005 1000 995 990 985 22 Shutdown Current vs. Input -40 4.90 4.85 4.80 4.75 4.70 4.65 4.60 4.55 4.50 4.45 -40 -10 FIGURE 2-20: Temperature. 20 50 80 Ambient Temperature (°C) IOUT = 0.1A 3.298 3.296 IOUT = 1A 3.294 3.292 3.290 3.288 3.286 3.284 -40 -10 FIGURE 2-21: Temperature. DS22285A-page 10 20 50 80 Ambient Temperature (°C) Output Voltage vs. 110 110 5.45 IOUT = 0A 5.40 5.35 5.30 5.25 5.20 -40 -10 20 50 80 Ambient Temperature (°C) 110 FIGURE 2-23: Input Quiescent Current vs. Temperature (No Load, Switching). Non-Switching Quiscent Current (mA) 3.300 20 50 80 Ambient Temperature (°C) 5.50 110 Shutdown Current vs. -10 FIGURE 2-22: Oscillator Frequency vs. Temperature (IOUT = 300 mA). Switching Quiscent Current (mA) FIGURE 2-19: Voltage. Shutdown Current (µA) 1010 980 6 VOUT (V) 1015 2.42 2.40 IOUT = 0A 2.38 2.36 2.34 2.32 2.30 2.28 -40 -10 20 50 80 Ambient Temperature (°C) 110 FIGURE 2-24: Input Current vs. Temperature (No Load, No Switching). © 2011 Microchip Technology Inc. MCP16321/2 Note: Unless otherwise indicated, VIN = 12V, EN = Floating (Internally pulled up), CIN = 20 µF, COUT = 2x22 µF, L = 4.7 µH (XAL6060-472MEB), ILOAD = 200 mA, TA = +25°C. MCP16321 maximum output current = 1A. VOUT = 3.3V IOUT = 200 mA VIN = 12V 30 Typical Mininimum Duty Cycle = 7% Max VIN (V) 25 20 15 10 5 0 0.9 1.2 1.5 VOUT (V) 1.8 2.1 FIGURE 2-25: Maximum VIN to VOUT Ratio for Continuous Switching. VOUT = 3.3V IOUT = 50 mA VIN = 12V FIGURE 2-26: Waveforms. Startup From Enable. VOUT = 3.3V IOUT = 200 mA VIN = 12V Light Load Switching FIGURE 2-29: Startup From VIN. VOUT = 3.3V IOUT = 100 mA to 600 mA VIN = 12V VOUT = 3.3V IOUT = 500 mA VIN = 12V FIGURE 2-27: Waveforms. FIGURE 2-28: Heavy Load Switching © 2011 Microchip Technology Inc. FIGURE 2-30: Load Transient Response. DS22285A-page 11 MCP16321/2 Note: Unless otherwise indicated, VIN = 12V, EN = Floating (Internally pulled up), CIN = 20 µF, COUT = 2x22 µF, L = 4.7 µH (XAL6060-472MEB), ILOAD = 200 mA, TA = +25°C. MCP16321 maximum output current = 1A. VOUT = 3.3V IOUT = 200 mA VIN = 6V to 10V FIGURE 2-31: DS22285A-page 12 Line Transient Response. © 2011 Microchip Technology Inc. MCP16321/2 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE MCP16321/2 3x3 QFN Symbol 1 SW Output switch node, connects to the inductor and the bootstrap capacitor 2 VIN Input supply voltage pin for power and internal biasing 3.1 Description 3 VIN 4 SGND 5 VFB Output voltage feedback pin. Connect VFB to VOUT for fixed version and output resistor divider for adjustable version. 6 NC No Connection 7 NC No Connection 8 PG Power Good open-drain output, pulled up to a maximum of 6V 9 EN Enable input pin. Logic high enables the operation. Internally pulled up, pull EN pin low to disable regulator’s output. Maximum voltage on EN input is 6V. 10 BOOST Boost voltage that drives the internal NMOS control switch. A bootstrap capacitor is connected between the BOOST and SW pins. 11 VIN Input supply voltage pin for power and internal biasing 12 SW Output switch node, connects to the inductor and the bootstrap capacitor 13 SW Output switch node, connects to the inductor and the bootstrap capacitor 14 PGND GND supply for the internal low-side NMOS/integrated diode 15 PGND GND supply for the internal low-side NMOS/integrated diode 16 SW Output switch node, connects to the inductor and the bootstrap capacitor 17 EP Exposed Thermal Pad (EP); must be connected to GND Input supply voltage pin for power and internal biasing Primary signal ground Switch Pin (SW) The drain of the low-side N-Channel switch is connected internally to the source of the high-side N-Channel switch, and externally to the SW node, consisting of the inductor and bootstrap capacitor. The SW node can rise very fast as a result of the internal high-side switch turning on. It should be connected directly to the 4.7 µH inductor with a wide, short trace. 3.2 Power Supply Input Voltage Pin (VIN) Connect the input voltage source to VIN. The input source should be decoupled to GND using 2 x 10 µF capacitors. The amount of the capacitance depends on the impedance of the source and output current. The input capacitors provide AC current for the high-side power switch and a stable voltage source for the internal device power. This capacitor should be connected as close as possible to the VIN and GND pins. © 2011 Microchip Technology Inc. 3.3 Signal Ground Pin (SGND) This ground is used for the majority of the device, including the analog reference, control loop, and other circuits. 3.4 Feedback Voltage Pin (VFB) The VFB input pin is used to provide output voltage regulation by either using a resistor divider or VOUT directly. For the adjustable version, the VFB will be 0.9V typical with the output voltage in regulation. For the fixed version, the VFB will be equal to the corresponding VOUT value. 3.5 Power Good Pin (PG) PG is an open drain, active low output. The regulator output voltage is monitored and the PG line will remain low until the output voltage reaches the VOUT-UV threshold. Once the internal comparator detects that the output voltage is above the VOUT-UV threshold, an internal delay timer is activated. After a 10 ms delay, the PG open drain output pin can be pulled high, indicating that the output voltage is in regulation. The maximum voltage applied to the PG output pin should not exceed 6V. DS22285A-page 13 MCP16321/2 3.6 Enable Pin (EN) The EN input pin is a logic-level input used to enable or disable the device. A logic high (> 2.2V) will enable the regulator output, while a logic low (< 0.8V) will ensure that the regulator is disabled. This pin is internally pulled up to an internal reference and will be enabled when VIN > UVLO, unless the EN pin is pulled low. The maximum input voltage applied to the EN pin should not exceed 6V. 3.7 BOOST Pin (BOOST) This pin will provide the bootstrap voltage required for driving the upper internal NMOS switch of the buck regulator. An external ceramic capacitor placed between the BOOST input pin and the SW pin will provide the necessary drive voltage for the upper switch. During steady state operation, the capacitor is recharged on every low-side, synchronous switching cycle. If the Switch mode approaches 100% duty cycle for the high-side MOSFET, the device will automatically reduce the duty cycle switch to a minimum off time of 240 ns on every 8th cycle to recharge the boost capacitor. 3.8 Power Ground Pin (PGND) This is a separate ground connection used for the lowside synchronous switch to isolate switching noise from the rest of the device. 3.9 Exposed Thermal Pad (EP) There is no internal electrical connection between the Exposed Thermal Pad (EP) and the PGND and SGND pins. The EP must be connected to GND on the Printed Circuit Board (PCB). DS22285A-page 14 © 2011 Microchip Technology Inc. MCP16321/2 4.0 DETAILED DESCRIPTION 4.1 Device Overview The MCP16321/2 is a high-input voltage, step-down regulator, capable of supplying 1A/2A to a regulated output voltage from 0.9V to 5V. Internally, the 1 MHz oscillator provides a fixed frequency, while the Peak Current Mode Control architecture varies the duty cycle for output voltage regulation. An internal floating driver is used to turn the high-side integrated N-Channel MOSFET on and off. The power for this driver is derived from an external boost capacitor whose energy is replenished when the low-side N-Channel MOSFET is turned on. When the maximum duty cycle approaches 100%, the boost capacitor is replenished for 240 ns after every 8 cycles. 4.1.1 INTERNAL REFERENCE VOLTAGE VREF For the adjustable version, an integrated precise 0.9V reference combined with an external resistor divider sets the desired converter output voltage. The resistor divider can vary without affecting the control system gain. High-value resistors consume less current, but are more susceptible to noise. For the fixed version, an integrated precise voltage reference is set to the desired VOUT value and is directly connected to VOUT. 4.1.2 INTERNAL COMPENSATION All control system components necessary for stable operation over the entire device operating range are integrated, including the error amplifier and inductor current slope compensation. 4.1.3 EXTERNAL COMPONENTS External components consist of: • • • • Input capacitor Output filter (inductor and capacitor) Boost capacitor Resistor divider (adjustable version only) The selection of the external inductor, output capacitor, input capacitor and boost capacitor is dependent upon the output voltage and the maximum output current. © 2011 Microchip Technology Inc. 4.1.4 ENABLE INPUT The enable input (EN) is used to disable the device. If disabled, the device consumes a minimal current from the input. Once enabled, the internal soft start controls the output voltage rate of rise, preventing high-inrush current and output voltage overshoot. The EN is internally pulled up or enabled; to disable the converter, it must be pulled low. 4.1.5 SOFT START The internal reference voltage rate of rise is controlled during startup, minimizing the output voltage overshoot and the inrush current. 4.1.6 OUTPUT OVER VOLTAGE PROTECTION If the output of the regulator exceeds 103% of the regulation voltage, the SW outputs will tri-state to protect the device from damage. This check occurs at the start of each switching cycle. 4.1.7 INPUT UNDER VOLTAGE LOCKOUT An integrated Under Voltage Lockout (UVLO) prevents the converter from starting until the input voltage is high enough for normal operation. The converter will typically start at 5.75V (typical) and operate down to 5.25V (typical). Hysteresis of 500 mV (typical) is added to prevent starting and stopping during startup, as a result of loading the input voltage source. 4.1.8 MINIMUM DUTY CYCLE A minimum duty cycle of 70 ns typical prevents the device from constant switching for high step-down voltage ratios. Duty cycles less than this minimum will initiate pulse skipping to maintain output voltage regulation, resulting in higher output voltage ripple. Duty cycle for continuous inductor current operation is approximated by VOUT/VIN. For a 1 MHz switching frequency or 1 µs period, this results in a 7% duty cycle minimum. Maximum VIN for continuous switching can be approximated dividing VOUT by the minimum duty cycle or 7%. For example, the maximum input voltage for continuous switching for a 1.5V output is equal to approximately 21V. DS22285A-page 15 MCP16321/2 4.1.9 OVERTEMPERATURE PROTECTION Overtemperature protection limits the silicon die temperature to +170°C by turning the converter off. The normal switching resumes at +160°C. VIN CIN UV Protection VOUT OTEMP Protection EN Monitor and Control 4.2V PG BOOST Voltage Current Limit VOUT RTOP Slope Comp OV Protection FB BOOST + RBOT CS + CBOOST VREF and Softstart + + COMP - PWM Comparator Amp HS Drive - Compensation 1 MHz Oscillator Gate Drive Control L VOUT Internal Bias LS Drive - VREF SW COUT COMP + PFM Comparator SGND FIGURE 4-1: DS22285A-page 16 PGND MCP16321/2 Block Diagram. © 2011 Microchip Technology Inc. MCP16321/2 4.2 Functional Description L 4.2.1 STEP-DOWN OR BUCK CONVERTER IL The MCP16321/2 is a synchronous, step-down or buck converter capable of stepping input voltages ranging from 6V to 24V down to 0.9V to 5V. The integrated high-side switch is used to chop or modulate the input voltage using a controlled duty cycle for output voltage regulation. The integrated low-side switch is used to freewheel current when the high-side switch is turned off. High efficiency is achieved by using low-resistance switches and low equivalent series resistance (ESR), inductor and capacitors. When the high-side switch is turned on, a DC voltage is applied to the inductor (VIN – VOUT), resulting in a positive linear ramp of inductor current. When the high-side switch turns off and the low-side switch turns on, the applied inductor voltage is equal to –VOUT, resulting in a negative linear ramp of inductor current. In order to ensure there is no shoot-through current, a dead time where both switches are off is implemented between the high-side switch turning off and the low-side switch turning on, and the low-side switch turning off and the high-side switch turning on. For steady-state, continuous inductor current operation, the positive inductor current ramp must equal the negative current ramp in magnitude. While operating in steady state, the switch duty cycle must be equal to the relationship of VOUT/VIN for constant output voltage regulation, under the condition that the inductor current is continuous, or never reaches zero. For discontinuous inductor current operation, the steady-state duty cycle will be less than VOUT/VIN to maintain voltage regulation. When the inductor current reaches zero, the low-side switch is turned off so that current does not flow in the reverse direction, keeping the efficiency high. The average of the chopped input voltage or SW node voltage is equal to the output voltage, while the average inductor current is equal to the output current. © 2011 Microchip Technology Inc. VOUT S1 COUT VIN S2 IL IOUT VIN SW VOUT S1 ON S2 ON Continuous Inductor Current Mode IL IOUT VIN SW S1 ON S2 Both ON OFF Discontinuous Inductor Current Mode FIGURE 4-2: Converter. Synchronous Step-Down DS22285A-page 17 MCP16321/2 4.2.2 PEAK CURRENT MODE CONTROL The MCP16321/2 integrates a Peak Current Mode Control architecture, resulting in superior AC regulation while minimizing the number of voltage loop compensation components, and their size, for integration. Peak Current Mode Control takes a small portion of the inductor current, replicates it and compares this replicated current sense signal with the output of the integrated error voltage. In practice, the inductor current and the internal switch current are equal during the switch-on time. By adding this peak current sense to the system control, the step-down power train system can be approximated by a 1st order system rather than a 2nd order system. This reduces the system complexity and increases its dynamic performance. For Pulse-Width Modulation (PWM) duty cycles that exceed 50%, the control system can become bimodal, where a wide pulse followed by a short pulse repeats instead of the desired fixed pulse width. To prevent this mode of operation, an internal compensating ramp is summed into the current sense signal. 4.2.3 PULSE WIDTH MODULATION (PWM) The internal oscillator periodically starts the switching period, which in the MCP16321/2’s case occurs every 1 µs or 1 MHz. With the high-side integrated N-Channel MOSFET turned on, the inductor current ramps up until the sum of the current sense and slope compensation ramp exceeds the integrated error amplifier output. Once this occurs, the high-side switch turns off and the low-side switch turns on. The error amplifier output slews up or down to increase or decrease the inductor peak current feeding into the output LC filter. If the regulated output voltage is lower than its target, the inverting error amplifier output rises. This results in an increase in the inductor current to correct for errors in the output voltage. The fixed frequency duty cycle is terminated when the sensed inductor peak current, summed with the internal slope compensation, exceeds the output voltage of the error amplifier. The PWM latch is set by turning off the highside internal switch and preventing it from turning on until the beginning of the next cycle. DS22285A-page 18 4.2.4 HIGH-SIDE DRIVE The MCP16321/2 features an integrated high-side N-Channel MOSFET for high efficiency step-down power conversion. An N-Channel MOSFET is used for its low resistance and size (instead of a P-Channel MOSFET). The N-Channel MOSFET gate must be driven above its source to fully turn on the device, resulting in a gate-drive voltage above the input to turn on the high-side N-Channel. The high-side N-Channel source is connected to the inductor and boost cap or switch node. When the high-side switch is off and the low-side is on, the inductor current flows through the low-side switch, providing a path to recharge the boost cap from the boost voltage source. An internal boostblocking diode is used to prevent current flow from the boost cap back into the output during the internal switch-on time. Prior to startup, the boost cap has no stored charge to drive the switch. An internal regulator is used to “pre-charge” the boost cap. Once precharged, the switch is turned on and the inductor current flows. When the high-side switch turns off and the low-side turns on, current freewheels through the inductor and low-side switch, providing a path to recharge the boost cap. When the duty cycle approaches its maximum value, there is very little time for the boost cap to be recharged due to the short amount time that the low-side switch is on. Therefore, when the maximum duty cycle approaches, the switch node is forced off for 240 ns every 8 cycles to ensure that the boost cap gets replenished. © 2011 Microchip Technology Inc. MCP16321/2 5.0 APPLICATION INFORMATION 5.0.1 TYPICAL APPLICATIONS The MCP16321/2 synchronous step-down converter operates over a wide input range, up to 24V maximum. Typical applications include generating a bias or VDD voltage for PIC® microcontrollers, digital control system bias supply for AC-DC converters and 12V industrial input and similar applications. 5.0.2 ADJUSTABLE OUTPUT VOLTAGE CALCULATIONS 5.0.3 The step-down converter duty cycle can be estimated using Equation 5-2 while operating in Continuous Inductor Current Mode. This equation accounts for the forward drop of two internal N-Channel MOSFETS. As load current increases, the voltage drop in both internal switches will increase, requiring a larger PWM duty cycle to maintain the output voltage regulation. Switch voltage drop is estimated by multiplying the switch current times the switch resistance or RDSON. EQUATION 5-2: To calculate the resistor divider values for the MCP16321/2 adjustable version, use Equation 5-1. RTOP is connected to VOUT, RBOT is connected to SGND, and both are connected to the VFB input pin. EQUATION 5-1: RESISTOR DIVIDER CALCULATION R TOP V OUT = V FB × ⎛⎝ 1 + ------------ ⎞⎠ R BOT EXAMPLE 5-1: 2.0V RESISTOR DIVIDER VOUT = 2.0V VFB = 0.9V RBOT = 10 kΩ RTOP = 12.2 kΩ (standard value = 12.3 kΩ) VOUT = 2.007V (using standard values) EXAMPLE 5-2: 4.2V RESISTOR DIVIDER VOUT = 4.2V VFB = 0.9V RBOT = 10 kΩ RTOP = 36.7 kΩ (standard value = 36.5 kΩ) VOUT = 4.185V (using standard values) The error amplifier is internally compensated to ensure loop stability. External resistor dividers, inductance and output capacitance, all have an impact on the control system and should be selected carefully and evaluated for stability. A 10 kΩ resistor is recommended as a good trade-off for quiescent current and noise immunity. GENERAL DESIGN EQUATIONS CONTINUOUS INDUCTOR CURRENT DUTY CYCLE V OUT + ( I LSW × R DSONL ) D = ------------------------------------------------------------V IN – ( I HSW × R DSONH ) 5.0.4 INPUT CAPACITOR SELECTION The step-down converter input capacitor must filter the high-input ripple current, as a result of pulsing or chopping the input voltage. The MCP16321/2 input voltage pin is used to supply voltage for the power train and as a source for internal bias. A low equivalent series resistance (ESR), preferably a ceramic capacitor, is recommended. The necessary capacitance is dependent upon the maximum load current and source impedance. Three capacitor parameters to keep in mind are the voltage rating, equivalent series resistance and the temperature rating. For wide temperature range applications, a multilayer X7R dielectric is recommended, while for applications with limited temperature range, a multilayer X5R dielectric is acceptable. The input capacitor voltage rating must be VIN plus margin. 5.0.5 OUTPUT CAPACITOR SELECTION The output capacitor provides a stable output voltage during sudden load transients, and reduces the output voltage ripple. As with the input capacitor, X5R and X7R ceramic capacitors are well suited for this application. The MCP16321/2 is internally compensated, so the output capacitance range is limited. See TABLE 5-1: “Capacitor Value Range” for the recommended output capacitor range. The amount and type of output capacitance and equivalent series resistance will have a significant effect on the output ripple voltage and system stability. The range of the output capacitance is limited due to the integrated compensation of the MCP16321/2. The output voltage capacitor rating should be a minimum of VOUT plus margin. TABLE 5-1: © 2011 Microchip Technology Inc. CAPACITOR VALUE RANGE Parameter Min Max CIN 8 µF None DS22285A-page 19 MCP16321/2 TABLE 5-1: CAPACITOR VALUE RANGE Parameter Min Max COUT 33 µF None 5.0.6 INDUCTOR SELECTION The MCP16321/2 is designed to be used with small surface mount inductors. Several specifications should be considered prior to selecting an inductor. To optimize system performance, low ESR inductors should be used. EQUATION 5-3: INDUCTOR CURRENT RIPPLE V Δ I L = -----L- × t ON L TABLE 5-2: MCP16321 RECOMMENDED INDUCTORS Value (µH) DCR (Ω) ISAT (A) Size WxLxH (mm) 1008PS 4.7 0.35 1.7 3.81x3.78x2.74 LPS4012 4.7 0.175 1.8 4.1x4.1x1.2 LPS4018 4.7 0.125 1.9 4.1x4.1x1.8 LPS5015 4.7 0.15 1.8 5x5x1.5 MSS5121 4.7 0.095 1.66 5.1x5.1x2.2 LPS5030 4.7 0.083 2 5x5x3 MSS6122 4.7 0.065 1.82 6.1x6.1x2.2 MOS6020 4.7 0.05 1.94 6.8x6x2.4 Part Number Coilcraft® Wurth Elektronik® EXAMPLE 5-3: MCP16321 PEAK INDUCTOR CURRENT – 1A VIN = 12V 744042 4.7 0.07 1.65 4.8x4.8x1.8 744068 4.7 0.072 1.55 8x8x1.1 7448944 4.7 0.0545 4.2 8x8x3.8 LTF5022T 4.7 0.073 2 5.2x5x2.2 VLC5020T 4.7 0.097 2 5x5x2 EPCOS® VOUT = 3.3V IOUT = 1A L = 4.7 µH Δ IL I LPK = --------- + IOUT 2 Inductor ripple current = 509 mA VLC6020T 4.7 0.079 1.8 6x6x2 VLCF5020T 4.7 0.122 1.7 5x5x2 VLF5014ST 4.7 0.12 1.7 4.8x4.6x1.4 TABLE 5-3: Inductor peak current = 1.255A An inductor saturation rating minimum of 1.255A is recommended. A trade-off between size, cost and efficiency is made to achieve the desired results. EXAMPLE 5-4: MCP16322 PEAK INDUCTOR CURRENT – 2A MCP16322 RECOMMENDED INDUCTORS Value (µH) DCR (Ω) ISAT (A) Size WxLxH (mm) MSS6132-472 4.7 0.056 2.84 6.1x6.1x3.2 Part Number Coilcraft® LPS6225-472 4.7 0.065 3.2 6.2x6.2x2.5 VIN = 12V MSS7341-502 4.7 0.024 3.16 7.3x7.3x4.1 VOUT = 3.3V DO1813H-472 4.7 0.054 2.6 8.89x6.1x5.0 IOUT = 2A Wurth Elektronik® L = 4.7 µH 7447785004 4.7 0.06 2.5 5.9x6.2x3.3 Δ IL I LPK = --------- + IOUT 2 7447786004 4.7 0.057 2.8 5.9x6.2x5.1 7447789004 4.7 0.033 3.9 7.3x3.2x1.5 EPCOS ® Inductor ripple current = 509 mA B82464G2 4.7 0.033 3.1 10.4x10.4x3.0 Inductor peak current = 2.255A B82464A2 4.7 0.03 4.5 10.4x10.4x3.0 An inductor saturation rating minimum of 2.255A is recommended. A trade-off between size, cost and efficiency is made to achieve the desired results. DS22285A-page 20 © 2011 Microchip Technology Inc. MCP16321/2 5.0.7 BOOST CAPACITOR The boost capacitor is used to supply current for the internal high-side drive circuitry that is above the input voltage. The boost capacitor must store enough energy to completely drive the high-side switch on and off. A 22 nF X5R or X7R capacitor is recommended for all applications. The boost capacitor maximum voltage is 5.5V, so a 6.3V or 10V rated capacitor is recommended. 5.0.8 EXAMPLE 5-5: To quickly estimate the internal power dissipation for the switching step-down regulator, an empirical calculation using measured efficiency can be used. Given the measured efficiency, the internal power dissipation is estimated in Equation 5-4. This power dissipation includes all internal and external component losses. For a quick internal estimate, subtract the estimated inductor ESR loss from the PDIS calculation in Equation 5-4. EQUATION 5-4: TOTAL POWER DISSIPATION ESTIMATE V OUT × I OUT PDIS = ------------------------------- – ( VOUT × I OUT ) Efficency The difference between the first term, input power, and the second term, power delivered, is the total system power dissipation. The inductor losses are estimated by PL = IOUT2 x LESR. VIN = 12V VOUT = IOUT = 5.0V Efficiency = 92.5% = 405 mW LESR = 0.04 Ω PL = 40 mW MCP16321 internal power dissipation estimate: PDIS – PL = θJA = Estimated Junction = 365 mW 38.5°C/W +14.052°C Note 1: θJA = 38.5°C/W for a 4-layer FR4 Printed Circuit Board with a 13.5 in2, 1 oz internal copper ground plane. 2: A smaller ground plane will result in a larger θJA temperature rise. EXAMPLE 5-6: POWER DISSIPATION – MCP16322 VIN = 12V VOUT = 3.3V IOUT = 2A Efficiency = 87.5% Total System Dissipation = 943 mW LESR = PL = 0.04 Ω 160 mW MCP16322 internal power dissipation estimate: PDIS – PL = θJA = Estimated Junction © 2011 Microchip Technology Inc. 1A Total System Dissipation THERMAL CALCULATIONS The MCP16321/2 is available in a 3x3 QFN-16 package. By calculating the power dissipation and applying the package thermal resistance (θJA), the junction temperature is estimated. The maximum continuous junction temperature rating for the MCP16321/2 is +125°C. POWER DISSIPATION – MCP16321 = 783 mW 38.5°C/W +30.14°C DS22285A-page 21 MCP16321/2 5.0.9 PCB LAYOUT INFORMATION frequency switch current, CIN also provides a stable voltage source for the internal MCP16321/2 circuitry. Unstable PWM operation can result if there are excessive transients or ringing on the VIN pin of the MCP16321/2 device. In Figure 5-1, CIN is placed close to the VIN pins. A ground plane on the bottom of the board provides a low resistive and low inductive path for the return current. The next priority in placement is the freewheeling current loop formed by COUT and L while strategically placing the COUT return close to CIN return. Next, CBOOST should be placed between the boost pin and the switch node pin. This leaves space close to the MCP16321/2 VFB pin to place RTOP and RBOT. RTOP and RBOT are routed away from the switch node so noise is not coupled into the high-impedance VFB input. Good printed circuit board layout techniques are important to any switching circuitry, and switching power supplies are no different. When wiring the switching high-current paths, short and wide traces should be used. Therefore, it is important that the input and output capacitors be placed as close as possible to the MCP16321/2 to minimize the loop area. The feedback resistors and feedback signal should be routed away from the switching node and the switching current loop. When possible, ground planes and traces should be used to help shield the feedback signal and minimize noise and magnetic interference. A good MCP16321/2 layout starts with CIN placement. CIN supplies current to the input of the circuit when the switch is turned on. In addition to supplying high- Bottom layer is ground plane VOUT COUT L COUT RPG 10Ω CBOOST GND MCP16321/2 RBOT RTOP Trace on bottom layer CIN VIN FIGURE 5-1: DS22285A-page 22 CIN GND Recommended Layout. © 2011 Microchip Technology Inc. MCP16321/2 CBOOST VOUT 0.9V to 5V L BOOST VIN 6.0V to 24V SW VIN MCP16321/2 10Ω EN CIN RTOP COUT VFB VOUT RBOT RPG PG SGND FIGURE 5-2: TABLE 5-4: PGND Recommended Layout – Schematic. RECOMMENDED LAYOUT COMPONENTS Component Value CIN 2 x 10 µF COUT 2 x 22 µF L 4.7 µH RTOP 36.5 kΩ RBOT 10 kΩ RPG 10 kΩ CBOOST 22 nF © 2011 Microchip Technology Inc. DS22285A-page 23 MCP16321/2 NOTES: DS22285A-page 24 © 2011 Microchip Technology Inc. MCP16321/2 6.0 PACKAGING INFORMATION 6.1 Package Marking Information 16-Lead QFN (3x3x0.9 mm) Example Part Number Legend: XX...X Y YY WW NNN e3 * Note: Code MCP16321T-150E/NG AAA MCP16321T-180E/NG AAB MCP16321T-250E/NG AAC MCP16321T-330E/NG AAD MCP16321T-500E/NG AAE MCP16321T-ADJE/NG AAF MCP16322T-150E/NG ABA MCP16322T-180E/NG ABB MCP16322T-250E/NG ABC MCP16322T-330E/NG ABD MCP16322T-500E/NG ABE MCP16322T-ADJE/NG ABF AAA E114 5256 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. © 2011 Microchip Technology Inc. DS22285A-page 25 MCP16321/2 DS22285A-page 26 © 2011 Microchip Technology Inc. MCP16321/2 © 2011 Microchip Technology Inc. DS22285A-page 27 MCP16321/2 DS22285A-page 28 © 2011 Microchip Technology Inc. MCP16321/2 APPENDIX A: REVISION HISTORY Revision A (December 2011) • Original Release of this Document. © 2011 Microchip Technology Inc. DS22285A-page 29 MCP16321/2 NOTES: DS22285A-page 30 © 2011 Microchip Technology Inc. MCP16321/2 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. Device T -XXX /XX Tape and Reel Output Temperature Package Range Voltage Device: MCP16321T: MCP16322T: Output Voltage 150 180 250 330 500 ADJ Temperature Range: E Package: X = = = = = = High-Efficiency Synchronous Buck Regulator (Tape and Reel) (QFN) High-Efficiency Synchronous Buck Regulator (Tape and Reel) (QFN) 1.5V 1.8V 2.5V 3.3V 5.0V Adjustable Examples: a) MCP16321T-150E/NG: b) MCP16321T-ADJE/NG: c) MCP16322T-150E/NG: d) MCP16322T-ADJE/NG: Tape and Reel, 1.5V Output Voltage, Extended Temperature 16LD QFN Package Tape and Reel, Adjustable Output Voltage, Extended Temperature 16LD QFN Package Tape and Reel, 1.5V Output Voltage, Extended Temperature 16LD QFN Package Tape and Reel, Adjustable Output Voltage, Extended Temperature 16LD QFN Package = -40°C to +125°C NG = Plastic Quad Flat, No Lead Package (3x3x0.9 mm Body) (QFN), 16-lead © 2011 Microchip Technology Inc. DS22285A-page 31 MCP16321/2 NOTES: DS22285A-page 32 © 2011 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. 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Analog-for-the-Digital Age, Application Maestro, chipKIT, chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2011, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. ISBN: 978-1-61341-865-9 Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. © 2011 Microchip Technology Inc. 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