MCP1603 2.0 MHz, 500 mA Synchronous Buck Regulator Features General Description • • • • • The MCP1603 is a high efficient, fully integrated 500 mA synchronous buck regulator whose 2.7V to 5.5V input voltage range makes it ideally suited for applications powered from 1-cell Li-Ion or 2-cell/3-cell NiMH/NiCd batteries. • • • • • • • • Over 90% Typical Efficiency Output Current Up To 500 mA Low Quiescent Current = 45 µA, typical Low Shutdown Current = 0.1 µA, typical Adjustable Output Voltage: - 0.8V to 4.5V Fixed Output Voltage: - 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V 2.0 MHz Fixed-Frequency PWM (Heavy Load) Automatic PWM to PFM Mode Transition 100% Duty Cycle Operation Internally Compensated Undervoltage Lockout (UVLO) Overtemperature Protection Space Saving Packages: - 5-Lead TSOT - 8-Lead 2X3 DFN At heavy loads, the MCP1603 operates in the 2.0 MHz fixed frequency PWM mode which provides a low noise, low output ripple, small-size solution. When the load is reduced to light levels, the MCP1603 automatically changes operation to a PFM mode to minimize quiescent current draw from the battery. No intervention is necessary for a smooth transition from one mode to another. These two modes of operation allow the MCP1603 to achieve the highest efficiency over the entire operating current range. The MCP1603 is available with either an adjustable or fixed output voltage. The available fixed output voltage options are 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V. When a fixed option is used, only three additional small external components are needed to form a complete solution. Couple this with the low profile, small-foot print packages and the entire system solution is achieved with minimal size. Applications • • • • • • • Cellular Telephones Portable Computers Organizers / PDAs USB Powered Devices Digital Cameras Portable Equipment +5V or +3.3V Distributed Systems Additional protection features include: overtemperature, and overcurrent protection. UVLO, Package Types 8-Lead 2x3 DFN 5-Lead TSOT VIN 1 GND 2 SHDN 3 5 4 LX VFB/VOUT MCP1603 © 2007 Microchip Technology Inc. SHDN 1 GND 2 LX 3 5 4 VFB/VOUT VIN LX 1 8 GND NC 2 7 VIN SHDN 3 6 NC VFB/VOUT 4 5 NC MCP1603L DS22042A-page 1 MCP1603 Typical Application Circuit L1 4.7 µH VIN 2.7V To 4.5V LX VIN CIN 4.7 µF VOUT 1.8V @ 500 mA COUT 4.7 µF SHDN VFB Efficiency (%) GND 100 95 90 85 80 75 70 65 60 55 50 VOUT = 1.8V VIN = 2.7V VIN = 3.6V VIN = 4.5V 0.1 1 10 100 1000 Output Current (mA) DS22042A-page 2 © 2007 Microchip Technology Inc. MCP1603 Functional Block Diagram VIN Band Gap UVLO Thermal Shutdown UVLO TSD VREF Soft Start SHDN IPK Limit IPEAKPWM ILIMPWM ILIMPFM IPEAKPFM Slope Comp OSC -ILPK S R Q POFF Q Switch Drive Logic and timing NOFF LX PWM/PFM PFM Error Amp VREF PWM Error Amp EA PWM/PFM Logic GND IPEAKPFM IPEAKPWM -ILPK -IPK Limit VREF OV Threshold Disable Switcher VFB / VOUT © 2007 Microchip Technology Inc. UVLO TSD UV Threshold DS22042A-page 3 MCP1603 1.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings † VIN - GND.......................................................................+6.0V All Other I/O ...............................(GND - 0.3V) to (VIN + 0.3V) LX to GND .............................................. -0.3V to (VIN + 0.3V) Output Short Circuit Current..................................Continuous Power Dissipation (Note 5) ..........................Internally Limited Storage Temperature.....................................-65°C to +150°C Ambient Temp. with Power Applied.................-40°C to +85°C Operating Junction Temperature...................-40°C to +125°C ESD Protection On All Pins: HBM..............................................................................4 kV MM...............................................................................300V † Notice: Stresses above those listed under "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. DC CHARACTERISTICS Electrical Characteristics: Unless otherwise indicated, VIN = SHDN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, IOUT = 100 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C. Parameters Sym Min Typ Max Units Conditions VIN 2.7 — 5.5 V Note 1 — mA Note 1 Input Characteristics Input Voltage Maximum Output Current IOUT 500 — Shutdown Current IIN_SHDN — 0.1 1 µA SHDN = GND Quiescent Current IQ — 45 60 µA SHDN = VIN, IOUT = 0 mA Shutdown/UVLO/Thermal Shutdown Characteristics SHDN, Logic Input Voltage Low VIL — — 15 %VIN VIN = 2.7V to 5.5V SHDN, Logic Input Voltage High VIH 45 — — %VIN VIN = 2.7V to 5.5V IL_SHDN -1.0 ±0.1 1.0 µA VIN = 2.7V to 5.5V UVLO 2.12 2.28 2.43 V VIN Falling Undervoltage Lockout Hysteresis UVLOHYS Thermal Shutdown TSHD — 140 — mV — 150 — °C Note 4, Note 5 Thermal Shutdown Hysteresis — 10 — °C Note 4, Note 5 SHDN, Input Leakage Current Undervoltage Lockout Note 1: 2: 3: 4: 5: 6: TSHD-HYS The minimum VIN has to meet two conditions: VIN ≥ 2.7V and VIN ≥ VOUT + 0.5V. Reference Feedback Voltage Tolerance applies to adjustable output voltage setting. VR is the output voltage setting. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable temperature and the thermal resistance from junction to air (i.e. TA, TJ, θJA). Exceeding the maximum allowable power dissipation causes the device to initiate thermal shutdown. The internal MOSFET switches have an integral diode from the LX pin to the VIN pin, and from the LX pin to the GND pin. In cases where these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not able to limit the junction temperature for these cases. The current limit threshold is a cycle-by-cycle peak current limit. DS22042A-page 4 © 2007 Microchip Technology Inc. MCP1603 DC CHARACTERISTICS (CONTINUED) Electrical Characteristics: Unless otherwise indicated, VIN = SHDN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, IOUT = 100 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C. Parameters Sym Min Typ Max VOUT VFB Units Conditions 0.8 — 4.5 V — 0.8 — V -3.0 — +3.0 % TA = -40°C to +25°C -2.5 — +2.5 % TA = +25°C to +85°C Output Characteristics Adjustable Output Voltage Range Reference Feedback Voltage Reference Feedback Voltage Tolerance Note 2 Feedback Input Bias Current IVFB — 0.1 — nA Output Voltage Tolerance Fixed VOUT -3.0% VR +3.0% % TA = -40°C to +25°C, Note 3 VOUT -2.5 VR +2.5 % TA = +25°C to +85°C, Note 3 Line Regulation VLINE- — 0.3 — %/V Load Regulation VLOAD- — 0.35 — % FOSC 1.5 2.0 2.8 MHz TSS — 0.6 — ms TR = 10% to 90% RDSon P-Channel RDSon-P — 500 — mΩ IP = 100 mA RDSon N-Channel RDSon-N — 500 — mΩ IN = 100 mA ILX -1.0 ±0.1 1.0 µA SHDN = 0V, VIN = 5.5V, LX = 0V, LX = 5.5V +ILX(MAX) — 860 — mA Note 6 REG REG Internal Oscillator Frequency Start Up Time LX Pin Leakage Current Positive Current Limit Threshold Note 1: 2: 3: 4: 5: 6: VIN = VR + 1V to 5.5V, IOUT = 100 mA VIN = VR +1.5V, ILOAD = 100 mA to 500 mA The minimum VIN has to meet two conditions: VIN ≥ 2.7V and VIN ≥ VOUT + 0.5V. Reference Feedback Voltage Tolerance applies to adjustable output voltage setting. VR is the output voltage setting. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable temperature and the thermal resistance from junction to air (i.e. TA, TJ, θJA). Exceeding the maximum allowable power dissipation causes the device to initiate thermal shutdown. The internal MOSFET switches have an integral diode from the LX pin to the VIN pin, and from the LX pin to the GND pin. In cases where these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not able to limit the junction temperature for these cases. The current limit threshold is a cycle-by-cycle peak current limit. © 2007 Microchip Technology Inc. DS22042A-page 5 MCP1603 TEMPERATURE SPECIFICATIONS Electrical Specifications: Unless otherwise indicated, all limits are specified for: VIN + 2.7V to 5.5V Parameters Sym Min Typ Max Units Conditions Operating Junction Temperature Range TJ -40 — +125 °C Storage Temperature Range TA -65 — +150 °C Maximum Junction Temperature TJ — — +150 °C Thermal Resistance, 5L-TSOT θJA — 256 — °C/W Typical 4-layer Board with Internal Ground Plane Thermal Resistance, 8L-2x3 DFN θJA — 84.5 — °C/W Typical 4-layer Board with Internal Ground Plane and 2-Vias in Thermal Pad Temperature Ranges Steady State Transient Package Thermal Resistances DS22042A-page 6 © 2007 Microchip Technology Inc. MCP1603 2.0 TYPICAL PERFORMANCE CURVES Note: 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. 50 49 48 47 46 45 44 43 42 41 40 52 VOUT = 1.8V Quiescent Current (µA) Quiescent Current (µA) Note: Unless otherwise indicated, VIN = SHDN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, ILOAD = 100 mA, TA = +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics. VIN = 3.6V VIN = 4.2V VIN = 3.0V o TA = +90 C 50 48 46 o TA = +25 C 44 42 o TA = - 40 C 40 -40 -25 -10 5 20 35 50 65 80 95 110 125 2.7 3.05 3.4 o Ambient Temperature ( C) FIGURE 2-1: IQ vs. Ambient Temperature. FIGURE 2-4: VOUT = 1.2V 95 4.45 4.8 IOUT = 100 mA 90 85 80 IOUT = 300 mA 75 IOUT = 500 mA 70 70 IQ vs. Input Voltage. 50 40 30 20 3.4 3.75 4.1 4.45 4.8 5.15 VIN = 3.6V 60 60 3.05 5.5 VIN = 4.2V 0.1 1 Input Voltage (V) FIGURE 2-2: (VOUT = 1.2V). Efficiency vs. Input Voltage FIGURE 2-5: (VOUT = 1.2V). 1000 IOUT = 300 mA IOUT = 500 mA 75 Efficiency (%) 90 Efficiency vs. Output Load VIN = 2.7V 90 IOUT = 100 mA 80 100 100 VOUT = 1.8V 85 10 Output Current (mA) 100 95 5.5 VIN = 2.7V 80 65 2.7 5.15 VOUT = 1.2V 90 Efficiency (%) Efficiency (%) 4.1 100 100 Efficiency (%) 3.75 Input Voltage (V) 80 VIN = 3.6V 70 60 50 40 VIN = 4.2V 30 VOUT = 1.8V 20 70 2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5 0.1 Efficiency vs. Input Voltage © 2007 Microchip Technology Inc. 10 100 1000 Output Current (mA) Input Voltage (V) FIGURE 2-3: (VOUT = 1.8V). 1 FIGURE 2-6: (VOUT = 1.8V). Efficiency vs. Output Load DS22042A-page 7 MCP1603 Typical Performance Curves (Continued) Note: Unless otherwise indicated, VIN = SHDN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, ILOAD = 100 mA, TA = +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics. 100 IOUT = 300 mA IOUT = 500 mA 85 Efficiency (%) 90 VIN = 2.7V 90 IOUT = 100 mA 95 Efficiency (%) 100 VOUT = 2.4V 80 80 VIN = 3.6V 70 60 50 40 75 VIN = 4.2V VOUT = 2.4V 30 3 3.5 4 4.5 5 5.5 0.1 1 Input Voltage (V) FIGURE 2-7: (VOUT = 2.4V). Efficiency vs. Input Voltage 100.0 FIGURE 2-10: (VOUT = 2.4V). IOUT = 100 mA 92.5 90.0 IOUT = 500 mA 87.5 80 85.0 4.25 4.5 4.75 5 Efficiency vs. Output Load VIN = 3.6V 70 60 50 VIN = 4.2V 40 4 VOUT = 3.3V 30 5.25 5.5 0.1 1 Input Voltage (V) FIGURE 2-8: (VOUT = 3.3V). 10 100 1000 Output Current (mA) Efficiency vs. Input Voltage 0.6 FIGURE 2-11: (VOUT = 3.3V). 1.82 VOUT = 1.8V 0.5 IOUT = 300 mA 0.4 0.3 IOUT = 100 mA 0.2 1.81 Output Voltage (V) Line Regualtion (%/V) 1000 90 IOUT = 300 mA 95.0 3.5 3.75 100 100 VOUT = 3.3V Efficiency (%) Efficiency (%) 97.5 10 Output Current (mA) Efficiency vs. Output Load o o TA = +125 C TA = +90 C 1.80 1.79 o 1.78 TA = +25 C o TA = - 40 C 1.77 1.76 1.75 0.1 -40 -25 -10 5 20 35 50 65 80 95 110 125 o Ambient Temperature ( C) FIGURE 2-9: Line Regulation vs. Ambient Temperature (VOUT = 1.8V). DS22042A-page 8 1.74 100 150 200 250 300 350 400 450 500 Output Current (mA) FIGURE 2-12: Output Voltage vs. Load Current (VOUT = 1.8V). © 2007 Microchip Technology Inc. MCP1603 Typical Performance Curves (Continued) 2.20 Switching Frequency (MHz) Switching Frequency (MHz) Note: Unless otherwise indicated, VIN = SHDN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, ILOAD = 100 mA, TA = +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics. 2.15 2.10 2.05 2.00 1.95 -40 -25 -10 5 2.20 2.15 2.10 2.05 2.00 1.95 20 35 50 65 80 95 110 125 2.7 3.05 3.4 o FIGURE 2-13: Switching Frequency vs. Ambient Temperature. FIGURE 2-16: Input Voltage. 4.1 4.45 4.8 5.15 5.5 Switching Frequency vs. 0.9 Switch Resistance (mΩ) 0.65 Switch Resistance (mΩ) 3.75 Input Voltage (V) Ambient Temperature ( C) 0.60 0.55 0.50 N-Channel P-Channel 0.45 0.40 0.8 N-Channel 0.7 0.6 0.5 0.4 P-Channel 0.3 0.35 2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 o Input Voltage (V) Ambient Temperature ( C) FIGURE 2-14: Voltage. Switch Resistance vs. Input FIGURE 2-17: Switch Resistance vs. Ambient Temperature. FIGURE 2-15: Waveform. Output Voltage Startup FIGURE 2-18: Waveform. © 2007 Microchip Technology Inc. Heavy Load Switching DS22042A-page 9 MCP1603 Typical Performance Curves (Continued) Note: Unless otherwise indicated, VIN = SHDN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, ILOAD = 100 mA, TA = +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics. FIGURE 2-19: Waveform. Light Load Switching FIGURE 2-21: Output Voltage Line Step Response vs. Time. FIGURE 2-20: Output Voltage Load Step Response vs. Time. DS22042A-page 10 © 2007 Microchip Technology Inc. MCP1603 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE Pin No. Description Symbol MCP1603 TSOT23 MCP1603L TSOT23 2x3 DFN 1 4 7 2 2 8 GND 3 1 3 SHDN 4 5 4 VFB/VOUT 5 3 1 LX Switch Node, Buck Inductor Connection Pin — — 2, 5, 6 NC No Connect — — Exposed Pad EP For the DFN package, the center exposed pad is a thermal path to remove heat from the device. Electrically this pad is at ground potential and should be connected to GND 3.1 VIN Power Supply Input Voltage Pin (VIN) Connect the input voltage source to VIN. The input source must be decoupled to GND with a 4.7 µF capacitor. 3.2 Ground Pin (GND) Ground pin for the device. The loop area of the ground traces should be kept as minimal as possible. 3.3 Shutdown Control Input Pin (SHDN) The SHDN pin is a logic-level input used to enable or disable the device. A logic high (> 45% of VIN) will enable the regulator output. A logic-low (< 15% of VIN) will ensure that the regulator is disabled. © 2007 Microchip Technology Inc. Power Supply Input Voltage Pin Ground Pin Shutdown Control Input Pin Feedback / Output Voltage Pin 3.4 Feedback / Output Voltage Pin (VFB/VOUT) For adjustable output options, connect the center of the output voltage divider to the VFB/VOUT pin. For fixedoutput voltage options, connect the output directly to the VFB/VOUT pin. 3.5 Switch Node, Buck Inductor Connection Pin (LX) Connect the LX pin directly to the buck inductor. This pin carries large signal-level current; all connections should be made as short as possible. 3.6 Exposed Metal Pad (EP) For the DFN package, connect the Exposed Pad to GND, with vias into the GND plane. This connection to the GND plane will aid in heat removal from the package. DS22042A-page 11 MCP1603 4.0 DETAILED DESCRIPTION 4.1 Device Overview The MCP1603 is a synchronous buck regulator that operates in a Pulse Frequency Modulation (PFM) mode or a Pulse Width Modulation (PWM) mode to maximize system efficiency over the entire operating current range. Capable of operating from a 2.7V to 5.5V input voltage source, the MCP1603 can deliver 500 mA of continuous output current. When using the MCP1603, the PCB area required for a complete step-down converter is minimized since both the main P-Channel MOSFET and the synchronous N-Channel MOSFET are integrated. Also while in PWM mode, the device switches at a constant frequency of 2.0 MHz (typ) which allow for small filtering components. Both fixed and adjustable output voltage options are available. The fixed voltage options (1.2V, 1.5V 1.8V, 2.5V, 3.3V) do not require an external voltage divider which further reduces the required circuit board footprint. The adjustable output voltage options allow for more flexibility in the design, but require an external voltage divider. Additionally the device features undervoltage lockout (UVLO), overtemperature shutdown, overcurrent protection, and enable/disable control. 4.2 Synchronous Buck Regulator The MCP1603 has two distinct modes of operation that allow the device to maintain a high level of efficiency throughout the entire operating current and voltage range. The device automatically switched between PWM mode and PFM mode depending upon the output load requirements. 4.2.1 FIXED FREQUENCY, PWM MODE During heavy load conditions, the MCP1603 operates at a high, fixed switching frequency of 2.0 MHz (typical) using current mode control. This minimizes output ripple (10 - 15 mV typically) and noise while maintaining high efficiency (88% typical with VIN = 3.6V, VOUT = 1.8V, IOUT = 300 mA). During normal PWM operation, the beginning of a switching cycle occurs when the internal P-Channel MOSFET is turned on. The ramping inductor current is sensed and tied to one input of the internal high-speed comparator. The other input to the high-speed comparator is the error amplifier output. This is the difference between the internal 0.8V reference and the divideddown output voltage. When the sensed current becomes equal to the amplified error signal, the highspeed comparator switches states and the P-Channel MOSFET is turned off. The N-Channel MOSFET is turned on until the internal oscillator sets an internal RS latch initiating the beginning of another switching cycle. PFM-to-PWM mode transition is initiated for any of the following conditions: • Continuous device switching • Output voltage has dropped out of regulation 4.2.2 LIGHT LOAD, PFM MODE During light load conditions, the MCP1603 operates in a PFM mode. When the MCP1603 enters this mode, it begins to skip pulses to minimize unnecessary quiescent current draw by reducing the number of switching cycles per second. The typical quiescent current draw for this device is 45 µA. PWM-to-PFM mode transition is initiated for any of the following conditions: • Discontinuous inductor current is sensed for a set duration • Inductor peak current falls below the transition threshold limit DS22042A-page 12 © 2007 Microchip Technology Inc. MCP1603 4.3 Soft Start The output of the MCP1603 is controlled during startup. This control allows for a very minimal amount of VOUT overshoot during start-up from VIN rising above the UVLO voltage or SHDN being enabled. 4.4 Overtemperature Protection Overtemperature protection circuitry is integrated in the MCP1603. This circuitry monitors the device junction temperature and shuts the device off, if the junction temperature exceeds the typical 150°C threshold. If this threshold is exceeded, the device will automatically restart once the junction temperature drops by approximately 10°C. The soft start is reset during an overtemperture condition. 4.5 Overcurrent Protection Cycle-by-cycle current limiting is used to protect the MCP1603 from being damaged when an external short circuit is applied. The typical peak current limit is 860 mA. If the sensed current reaches the 860 mA limit, the P-Channel MOSFET is turned off, even if the output voltage is not in regulation. The device will attempt to start a new switching cycle when the internal oscillator sets the internal RS latch. © 2007 Microchip Technology Inc. 4.6 Enable/Disable Control The SHDN pin is used to enable or disable the MCP1603. When the SHDN pin is pulled low, the device is disabled. When pulled high the device is enabled and begins operation provided the input voltage is not below the UVLO threshold or a fault condition exists. 4.7 Undervoltage Lockout (UVLO) The UVLO feature uses a comparator to sense the input voltage (VIN) level. If the input voltage is lower than the voltage necessary to properly operate the MCP1603, the UVLO feature will hold the converter off. When VIN rises above the necessary input voltage, the UVLO is released and soft start begins. Hysteresis is built into the UVLO circuit to compensate for input impedance. For example, if there is any resistance between the input voltage source and the device when it is operating, there will be a voltage drop at the input to the device equal to IIN x RIN. The typical hysteresis is 140 mV. DS22042A-page 13 MCP1603 5.0 APPLICATION INFORMATION 5.1 Typical Applications The MCP1603 500 mA synchronous buck regulator operates over a wide input voltage range (2.7V to 5.5V) and is ideal for single-cell Li-Ion battery powered applications, USB powered applications, three cell NiMH or NiCd applications and 3V or 5V regulated input applications. The 5-lead TSOT and 8-lead 2x3 DFN packages provide a small footprint with minimal external components. 5.2 Fixed Output Voltage Applications Typical Application Circuit shows a fixed MCP1603 in an application used to convert three NiMH batteries into a well regulated 1.8V @ 500 mA output. A 4.7 µF input capacitor, 4.7 µF output capacitor, and a 4.7 µH inductor make up the entire external component solution for this application. No external voltage divider or compensation is necessary. In addition to the fixed 1.8V option, the MCP1603 is also available in 1.2V, 1.5V, 2.5V, or 3.3V fixed voltage options. 5.3 Adjustable Output Voltage Applications When the desired output for a particular application is not covered by the fixed voltage options, an adjustable MCP1603 can be used. The circuit listed in Figure 6-2 shows an adjustable MCP1603 being used to convert a 5V rail to 1.0V @ 500 mA. The output voltage is adjustable by using two external resistors as a voltage divider. For adjustable-output voltages, it is recommended that the top resistor divider value be 200 kΩ. The bottom resistor value can be calculated using the following equation: EQUATION 5-1: V FB R BOT = R TOP × ⎛ -----------------------------⎞ ⎝ V OUT – V FB⎠ Example: RTOP = 200 kΩ VOUT = 1.0V VFB = 0.8V RBOT = 200 kΩ x (0.8V/(1.0V - 0.8V)) RBOT = 800 kΩ (Standard Value = 787 kΩ) DS22042A-page 14 For adjustable output applications, an additional R-C compensation network is necessary for control loop stability. Recommended values for any output voltage are: RCOMP = 4.99 kΩ CCOMP = 33 pF Refer to Figure 6-2 for proper placement of RCOMP and CCOMP. 5.4 Input Capacitor Selection The input current to a buck converter, when operating in continuous conduction mode, is a squarewave with a duty cycle defined by the output voltage (VOUT) to input voltage (VIN) relationship of VOUT/VIN. To prevent undesirable input voltage transients, the input capacitor should be a low ESR type with an RMS current rating given by Equation 5.5. Because of their small size and low ESR, ceramic capacitors are often used. Ceramic material X5R or X7R are well suited since they have a low temperature coefficient and acceptable ESR. EQUATION 5-2: ⎛ V OUT × ( V IN – V OUT )⎞ I CIN ,RMS = I OUT ,MAX × ⎜ -----------------------------------------------------⎟ V IN ⎝ ⎠ Table 5-1 contains the recommend range for the input capacitor value. 5.5 Output Capacitor Selection The output capacitor helps provide a stable output voltage during sudden load transients, smooths the current that flows from the inductor to the load, and reduces the output voltage ripple. Therefore, low ESR capacitors are a desirable choice for the output capacitor. As with the input capacitor, X5R and X7R ceramic capacitors are well suited for this application. The output ripple voltage is often a design specification. A buck converters’ output ripple voltage is a function of the charging and discharging of the output capacitor and the ESR of the capacitor. This ripple voltage can be calculated by Equation 5-3. EQUATION 5-3: Δ IL Δ V OUT = Δ I L × ESR + -------------------8×f×C © 2007 Microchip Technology Inc. MCP1603 Table 5-1 contains the recommend range for the output capacitor value. TABLE 5-1: 5.6 CAPACITOR VALUE RANGE CIN COUT Minimum 4.7 µF 4.7 µF Maximum — 22 µF Inductor Selection When using the MCP1603, the inductance value can range from 3.3 µH to 10 µH. An inductance value of 4.7 µH is recommended to achieve a good balance between converter load transient response and minimized noise. The value of inductance is selected to achieve a desired amount of ripple current. It is reasonable to assume a ripple current that is 20% of the maximum load current. The larger the amount of ripple current allowed, the larger the output capacitor value becomes to meet ripple voltage specifications. The inductor ripple current can be calculated according to the following equation. EQUATION 5-4: V OUT V OUT⎞ ΔI L = ------------------- × ⎛⎝ 1 – -----------F SW × L V IN ⎠ Where: FSW = Switching Frequency When considering inductor ratings, the maximum DC current rating of the inductor should be at least equal to the maximum load current, plus one half the peak-topeak inductor ripple current (1/2 * ΔIL). The inductor DC resistance adds to the total converter power loss. An inductor with a low DC resistance allows for higher converter efficiency. TABLE 5-2: MCP1603 RECOMMENDED INDUCTORS Value (µH) DCR Ω (max) ISAT (A) Size WxLxH (mm) SD3110 3.3 0.195 0.81 3.1x3.1x1.0 SD3110 4.7 0.285 0.68 3.1x3.1x1.0 Part Number Coiltronics® SD3110 6.8 0.346 0.58 3.1x3.1x1.0 SD3812 3.3 0.159 1.40 3.8x3.8x1.2 SD3812 4.7 0.256 1.13 3.8x3.8x1.2 SD3812 6.8 0.299 0.95 3.8x3.8x1.2 Würth Elektronik® WE-TPC Type XS 3.3 0.225 0.72 3.3x3.5x0.95 WE-TPC Type XS 4.7 0.290 0.50 3.3x3.5x0.95 WE-TPC Type S 4.7 0.105 0.90 3.8x3.8x1.65 WE-TPC Type S 6.8 0.156 0.75 3.8x3.8x1.65 CMD4D06 3.3 0.174 0.77 3.5x4.3x0.8 CMD4D06 4.7 0.216 0.75 3.5x4.3x0.8 CMD4D06 6.8 0.296 0.62 3.5x4.3x0.8 Sumida® 5.7 Thermal Calculations The MCP1603 is available in two different packages (TSOT-23 and 2x3 DFN). 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 MCP1603 is +125°C. To quickly estimate the internal power dissipation for the switching buck regulator, an empirical calculation using measured efficiency can be used. Given the measured efficiency, the internal power dissipation is estimated by: EQUATION 5-5: OUT × I OUT⎞ ⎛V ------------------------------ – ( V OUT × I OUT ) = P Diss ⎝ Efficiency ⎠ The difference between the first term, input power dissipation, and the second term, power delivered, is the internal power dissipation. This is an estimate assuming that most of the power lost is internal to the MCP1603. There is some percentage of power lost in the buck inductor, with very little loss in the input and output capacitors. © 2007 Microchip Technology Inc. DS22042A-page 15 MCP1603 5.8 PCB Layout Information Therefore, it is important that the components along the high current path should be placed as close as possible to the MCP1603 to minimize the loop area. Good printed circuit board layout techniques are important to any switching circuitry and switching power supplies are no different. When wiring the high current paths, short and wide traces should be used. This high current path is shown with red connections in Figure 5-1. The current in this path is switching. The feedback resistors and feedback signal should be routed away from the switching node and this switching current loop. When possible ground planes and traces should be used to help shield the feedback signal and minimize noise and magnetic interference. L1 4.7 µH VIN 2.7V To 4.5V VIN CIN 4.7 µF VOUT 1.8V @ 500 mA LX SHDN VFB COUT 4.7 µF GND FIGURE 5-1: DS22042A-page 16 PCB High Current Path. © 2007 Microchip Technology Inc. MCP1603 6.0 TYPICAL APPLICATION CIRCUITS l L1 4.7 µH VIN 3.0V To 4.2V VIN CIN 4.7 µF VOUT 1.5V @ 500 mA LX COUT 4.7 µF SHDN VFB GND FIGURE 6-1: Single Li-Ion to 1.5V @ 500 mA Application. L1 4.7 µH VIN 5.0V LX VIN CIN 4.7 µF SHDN RTOP 200 kΩ VFB GND FIGURE 6-2: RCOMP 4.99 kΩ VOUT 1.0V @ 500 mA CCOMP 33 pF COUT 4.7 µF RBOT 787 kΩ 5V to 1.0V @ 500 mA Application. L1 4.7 µH VIN 2.7V To 4.5V CIN 4.7 µF VOUT 1.2V @ 500 mA LX VIN SHDN VFB COUT 4.7 µF GND FIGURE 6-3: 3 NiMH Batteries to 1.2V @ 500 mA Application.9 © 2007 Microchip Technology Inc. DS22042A-page 17 MCP1603 7.0 PACKAGING INFORMATION 7.1 Package Marking Information (Not to Scale) 8-Lead 2x3 DFN Part Number XXX YWW NNN MCP1603-120I/MC MCP1603-150I/MC MCP1603-180I/MC MCP1603-250I/MC MCP1603-330I/MC MCP1603-ADJI/MC AFM AFK AFJ AFG AFA AFQ Part Number Marking Code 5-Lead TSOT XXNN Legend: XX...X Y YY WW NNN e3 * Note: DS22042A-page 18 Marking Code MCP1603T-120I/OS MCP1603T-150I/OS MCP1603T-180I/OS MCP1603T-250I/OS MCP1603T-330I/OS MCP1603T-ADJI/OS ETNN EUNN EVNN EWNN EXNN EYNN Part Number Marking Code MCP1603LT-120I/OS MCP1603LT-150I/OS MCP1603LT-180I/OS MCP1603LT-250I/OS MCP1603LT-330I/OS MCP1603LT-ADJI/OS FMNN FKNN EJNN FGNN FANN FQNN Example: AFM 711 25 Example ET25 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. © 2007 Microchip Technology Inc. MCP1603 8-Lead Plastic Dual Flat, No Lead Package (MC) – 2x3x0.9 mm Body [DFN] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging D e b N N L K E2 E EXPOSED PAD NOTE 1 2 1 2 NOTE 1 1 D2 BOTTOM VIEW TOP VIEW A A3 A1 NOTE 2 Units Dimension Limits Number of Pins MILLIMETERS MIN N NOM MAX 8 Pitch e Overall Height A 0.80 0.90 1.00 Standoff A1 0.00 0.02 0.05 Contact Thickness A3 0.20 REF Overall Length D 2.00 BSC Overall Width E Exposed Pad Length D2 1.30 – Exposed Pad Width E2 1.50 – 1.90 b 0.18 0.25 0.30 Contact Length L 0.30 0.40 0.50 Contact-to-Exposed Pad K 0.20 – – Contact Width 0.50 BSC 3.00 BSC 1.75 Notes: 1. Pin 1 visual index feature may vary, but must be located within the hatched area. 2. Package may have one or more exposed tie bars at ends. 3. Package is saw singulated. 4. Dimensioning and tolerancing per ASME Y14.5M. BSC: Basic Dimension. Theoretically exact value shown without tolerances. REF: Reference Dimension, usually without tolerance, for information purposes only. Microchip Technology Drawing C04-123B © 2007 Microchip Technology Inc. DS22042A-page 19 MCP1603 5-Lead Plastic Thin Small Outline Transistor (OS) [TSOT] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging b N E E1 NOTE 1 1 3 2 e e1 D α A A2 c φ L A1 β Units Dimension Limits Number of Leads L1 MILLIMETERS MIN NOM MAX N 5 Lead Pitch e 0.95 BSC Outside Lead Pitch e1 Overall Height A – – Molded Package Thickness A2 0.70 0.90 1.00 Standoff A1 0.00 – 0.10 1.90 BSC Overall Width E Molded Package Width E1 1.60 BSC Overall Length D 2.90 BSC 1.10 2.80 BSC Foot Length L Footprint L1 0.30 0.45 0.60 Foot Angle φ 0° 4° 8° Lead Thickness c 0.08 – 0.20 Lead Width b 0.30 – 0.50 Mold Draft Angle Top α 4° 10° 12° Mold Draft Angle Bottom β 4° 10° 0.60 REF 12° Notes: 1. Pin 1 visual index feature may vary, but must be located within the hatched area. 2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side. 3. Dimensioning and tolerancing per ASME Y14.5M. BSC: Basic Dimension. Theoretically exact value shown without tolerances. REF: Reference Dimension, usually without tolerance, for information purposes only. Microchip Technology Drawing C04-128B DS22042A-page 20 © 2007 Microchip Technology Inc. MCP1603 APPENDIX A: REVISION HISTORY Revision A (May 2007) • Original Release of this Document. © 2007 Microchip Technology Inc. DS22042A-page 21 MCP1603 NOTES: DS22042A-page 22 © 2007 Microchip Technology Inc. MCP1603 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 X X XXX X / XX TSOT Tape Voltage Temp. Package Config. and Reel Option Examples: 8-Lead DFN: a) b) Device: MCP1603: 2.0 MHz, 500 mA Buck Regulator TSOT Pin Config. Designator * Blank = Standard pinout L = Alternate pinout * Refer to Package Types for an explanation regarding the function of the device pins. c) d) e) MCP1603-120I/MC: 1.20V Buck Reg., 8LD-DFN pkg. MCP1603-150I/MC: 1.50V Buck Reg., 8LD-DFN pkg. MCP1603-180I/MC: 1.80V Buck Reg., 8LD-DFN pkg. MCP1603-250I/MC: 2.50V Buck Reg., 8LD-DFN pkg. MCP1603-330I/MC: 3.30V Buck Reg., 8LD-DFN pkg. T Blank = Tape and Reel = Tube 5-Lead TSOT: ADJ 120 150 180 250 330 = = = = = = Adjustable 1.20V “Standard” 1.50V “Standard” 1.80V “Standard” 2.50V “Standard” 3.30V “Standard” b) Temperature: I = -40°C to +85°C Package Type: MC = Plastic Dual-Flat No-Lead Package (MC), 8-Lead OS = Plastic Thin Small Outline Transistor (OS), 5-Lead Tape and Reel: Voltage Option: © 2007 Microchip Technology Inc. a) c) d) e) f) g) MCP1603T-120I/OS: 1.20V Buck Reg., 5LD-TSOT pkg. MCP1603T-180I/OS: 1.80V Buck Reg., 5LD-TSOT pkg. MCP1603T-250I/OS: 2.50V Buck Reg., 5LD-TSOT pkg. MCP1603T-330I/OS: 3.30V Buck Reg., 5LD-TSOT pkg. MCP1603T-ADJI/OS: Adj. Buck Reg., 5LD-TSOT pkg. MCP1603LT-250I/OS:2.50V Buck Reg., 5LD-TSOT pkg. MCP1603LT-ADJI/OS:Adj. Buck Reg., 5LD-TSOT pkg. DS22042A-page 23 MCP1603 NOTES: DS22042A-page 24 © 2007 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. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, KEELOQ logo, microID, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. AmpLab, FilterLab, Linear Active Thermistor, Migratable Memory, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Smart Serial, SmartTel, Total Endurance, UNI/O, 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. © 2007, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 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. © 2007 Microchip Technology Inc. DS22042A-page 25 WORLDWIDE SALES AND SERVICE AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://support.microchip.com Web Address: www.microchip.com Asia Pacific Office Suites 3707-14, 37th Floor Tower 6, The Gateway Habour City, Kowloon Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 India - Bangalore Tel: 91-80-4182-8400 Fax: 91-80-4182-8422 India - New Delhi Tel: 91-11-4160-8631 Fax: 91-11-4160-8632 Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 India - Pune Tel: 91-20-2566-1512 Fax: 91-20-2566-1513 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Japan - Yokohama Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Atlanta Duluth, GA Tel: 678-957-9614 Fax: 678-957-1455 Boston Westborough, MA Tel: 774-760-0087 Fax: 774-760-0088 Chicago Itasca, IL Tel: 630-285-0071 Fax: 630-285-0075 Dallas Addison, TX Tel: 972-818-7423 Fax: 972-818-2924 Detroit Farmington Hills, MI Tel: 248-538-2250 Fax: 248-538-2260 Kokomo Kokomo, IN Tel: 765-864-8360 Fax: 765-864-8387 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 Santa Clara Santa Clara, CA Tel: 408-961-6444 Fax: 408-961-6445 Toronto Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509 Australia - Sydney Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 China - Beijing Tel: 86-10-8528-2100 Fax: 86-10-8528-2104 China - Chengdu Tel: 86-28-8665-5511 Fax: 86-28-8665-7889 Korea - Gumi Tel: 82-54-473-4301 Fax: 82-54-473-4302 China - Fuzhou Tel: 86-591-8750-3506 Fax: 86-591-8750-3521 Korea - Seoul Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934 China - Hong Kong SAR Tel: 852-2401-1200 Fax: 852-2401-3431 Malaysia - Penang Tel: 60-4-646-8870 Fax: 60-4-646-5086 China - Qingdao Tel: 86-532-8502-7355 Fax: 86-532-8502-7205 Philippines - Manila Tel: 63-2-634-9065 Fax: 63-2-634-9069 China - Shanghai Tel: 86-21-5407-5533 Fax: 86-21-5407-5066 Singapore Tel: 65-6334-8870 Fax: 65-6334-8850 China - Shenyang Tel: 86-24-2334-2829 Fax: 86-24-2334-2393 Taiwan - Hsin Chu Tel: 886-3-572-9526 Fax: 886-3-572-6459 China - Shenzhen Tel: 86-755-8203-2660 Fax: 86-755-8203-1760 Taiwan - Kaohsiung Tel: 886-7-536-4818 Fax: 886-7-536-4803 China - Shunde Tel: 86-757-2839-5507 Fax: 86-757-2839-5571 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 China - Wuhan Tel: 86-27-5980-5300 Fax: 86-27-5980-5118 Thailand - Bangkok Tel: 66-2-694-1351 Fax: 66-2-694-1350 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 UK - Wokingham Tel: 44-118-921-5869 Fax: 44-118-921-5820 China - Xian Tel: 86-29-8833-7250 Fax: 86-29-8833-7256 12/08/06 DS22042A-page 26 © 2007 Microchip Technology Inc.