MCP1602 2.0 MHz, 500 mA Synchronous Buck Regulator with Power-Good Features General Description • • • • • • • The MCP1602 is a high efficient, fully integrated 500 mA synchronous buck regulator with a powergood monitor. The 2.7V to 5.5V input voltage range and low quiescent current (45 µA, typical) makes the MCP1602 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 Power-Good Output with 262 ms Delay Low Quiescent Current: 45 µA (typical) Low Shutdown Current: 0.05 µA (typical) Automatic PWM to PFM Mode Transition 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) Internally Compensated Undervoltage Lockout (UVLO) Overtemperture Protection Overcurrent Protection Space Saving Packages: - 8-Lead MSOP - 8-Lead 3x3 DFN Applications • • • • • • • Cellular Telephones Portable Computers Organizers / PDAs USB Powered Devices Digital Cameras Portable Equipment +5V or +3.3V Distributed Systems At heavy loads, the MCP1602 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 MCP1602 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 MCP1602 to achieve the highest efficiency over the entire operating current range. The open-drain power-good feature of the MCP1602 monitors the output voltage and provides indication when the output voltage is within 94% (typical) of the regulation value. The typical 2% hystereses in the power-good transition threshold as well as a 262 ms (typical) delay time ensures accurate powergood signaling. The MCP1602 is available in either the 8-pin DFN or MSOP package. It is also 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. Additional protection features include: overtemperature, and overcurrent protection. UVLO, Package Types MSOP-8 3x3 DFN-8 PGND 8 SHDN 1 8 PGND 2 VCC LX 7 VCC 2 7 LX 3 PG VIN 6 PG 3 6 VIN 4 AGND VOUT/VFB 5 AGND 4 5 VOUT/VFB 1 SHDN © 2007 Microchip Technology Inc. DS22061A-page 1 MCP1602 Typical Application Circuit 4.7 µH VIN 2.7V to 4.5V 4.7 µF LX 7 6 VIN 10Ω 2 VCC 0.1 µF 4 AGND 1 SHDN VOUT 1.5V @ 500 mA 4.7 µF VFB 5 PGND 8 PG 3 MCP1602 RPULLUP Processor Reset ON OFF VIN DS22061A-page 2 © 2007 Microchip Technology Inc. MCP1602 Functional Block Diagram VCC UVLO VIN VREF Band Gap Thermal Shutdown UVLO Soft Start SHDN ILIMPWM TSD ILIMPFM IPK Limit IPEAKPWM Disable Switcher IPEAKPFM Slope Comp OSC -ILPK S Q POFF LX NOFF Switch Drive R Q Logic and Timing PWM/PFM PFM Error Amp PWM/PFM Logic PGND IPEAKPFM VREF IPEAKPWM PWM Error Amp EA -ILPK -IPK Limit VREF VREF VCC PG OV Threshold PG Generator with Delay VFB / VOUT AGND UV Threshold VOUT © 2007 Microchip Technology Inc. DS22061A-page 3 MCP1602 1.0 ELECTRICAL CHARACTERISTICS † 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. Absolute Maximum Ratings † VIN - AGND ......................................................................+6.0V All Other I/O .............................. (AGND - 0.3V) to (VIN + 0.3V) LX to PGND ............................................. -0.3V to (VIN + 0.3V) Output Short Circuit Current..................................Continuous Power Dissipation (Note 6) ..........................Internally Limited Storage Temperature.................................... -65oC to +150oC Ambient Temp. with Power Applied................ -40oC to +85oC Operating Junction Temperature.................. -40oC to +125oC ESD Protection On All Pins: HBM..............................................................................3 kV MM...............................................................................200V DC CHARACTERISTICS Electrical Characteristics: Unless otherwise indicated, VIN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, IOUT = 100 mA, TA = +25°C. Boldface specifications apply for the TA range of -40oC to +85oC. Parameters Sym Min Typ Max Units VIN 2.7 — 5.5 V Conditions Input Characteristics Input Voltage Note 1 IOUT 500 — — mA Note 1 Shutdown Current IIN_SHDN — 0.05 1 µA SHDN = GND Quiescent Current IQ — 45 60 µA SHDN = VIN, IOUT = 0 mA Maximum Output Current 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 SHDN, Input Leakage Current Undervoltage Lockout Undervoltage Lockout Hysteresis VL_SHND -1.0 ±0.1 1.0 µA VIN = 2.7V to 5.5V, SHDN = AGND UVLO 2.40 2.55 2.70 V VIN Falling UVLOHYS — 200 — mV TSHD — 150 — °C Note 5, Note 6 TSHD-HYS — 10 — °C Note 5, Note 6 VOUT 0.8 — 4.5 V Note 2 Reference Feedback Voltage VFB — 0.8 — V Feedback Input Bias Current IVFB — -1.5 — nA Thermal Shutdown Thermal Shutdown Hysteresis Output Characteristics Adjustable Output Voltage Range Note 1: 2: 3: 4: 5: 6: 7: 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. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load range of 0.1 mA to the maximum specified output current. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 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 too. Thermal protection is not able to limit the junction temperature for these cases. The current limit threshold is a cycle-by-cycle current limit. DS22061A-page 4 © 2007 Microchip Technology Inc. MCP1602 DC CHARACTERISTICS (CONTINUED) Electrical Characteristics: Unless otherwise indicated, VIN = 3.6V, COUT = CIN = 4.7 µF, L = 4.7 µH, VOUT(ADJ) = 1.8V, IOUT = 100 mA, TA = +25°C. Boldface specifications apply for the TA range of -40oC to +85oC. Parameters Sym Min Typ Max Output Voltage Tolerance Fixed VOUT Line Regulation VLINE- Load Regulation VLOAD- Units -2.5 VR +2.5 % — 0.3 — %/V — 0.4 — % FOSC 1.6 2.0 2.4 MHz TSS — 0.5 — ms TR = 10% to 90% RDSon P-Channel RDSon-P — 450 — mΩ IP = 100 mA RDSon N-Channel RDSon-N — 450 — mΩ IN = 100 mA ILX -1.0 ±0.01 1.0 µA SHDN = 0V, VIN = 5.5V, LX = 0V, LX = 5.5V Positive Current Limit Threshold +ILX(MAX) Power-Good (PG) — 700 — mA Note 7 Voltage Range VPG 1.0 1.2 — 5.5 5.5 V PG Threshold High VTH_H — 94 96 % of VOUT On Rising VOUT PG Threshold Low VTH_L 89 92 — % of VOUT On Falling VOUT PG Threshold Hysteresis VTH_HYS — 2 — % of VOUT PG Threshold Tempco ΔVTH/ΔT — 30 — ppm/°C PG Delay tRPD — 165 — µs VOUT = (VTH_H + 100 mV) to (VTH_L - 100 mV) PG Active Time-out Period tRPU 140 262 560 ms VOUT = (VTH_L - 100 mV) to (VTH_H + 100 mV), ISINK = 1.2mA PG_VOL — — 0.2 V REG REG Internal Oscillator Frequency Start Up Time LX Pin Leakage Current PG Output Voltage Low Note 1: 2: 3: 4: 5: 6: 7: Conditions Note 3 VIN = VR + 1V to 5.5V, IOUT = 100 mA VIN = VR +1.5V, ILOAD = 100 mA to 500 mA, Note 1 TA = 0°C to +70°C TA = -40°C to +85°C VIN ≤ 2.7V, ISINK = 100 µA VOUT = VTH_L - 100 mV, IPG = 1.2 mA, VIN > 2.7V IPG = 100 µA, 1.0 < VIN < 2.7V 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. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load range of 0.1 mA to the maximum specified output current. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 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 too. Thermal protection is not able to limit the junction temperature for these cases. The current limit threshold is a cycle-by-cycle current limit. © 2007 Microchip Technology Inc. DS22061A-page 5 MCP1602 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, 8L-MSOP θJA — 211 — °C/W Typical 4-layer Board with Internal Ground Plane Thermal Resistance, 8L-3x3 DFN θJA — 60 — °C/W Typical 4-layer Board with Internal Ground Plane and 2-Vias in Thermal Pad Temperature Ranges Steady State Transient Package Thermal Resistances DS22061A-page 6 © 2007 Microchip Technology Inc. MCP1602 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. 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. 55 VOUT = 1.8V Quiescent Current (µA) Quiescent Current (µA) 60 55 VIN = 5.5V 50 45 VIN = 3.6V 40 VIN = 4.2V 35 30 -40 -25 -10 5 TA = +25°C TA = +90°C 50 45 TA = -40°C 40 35 30 20 35 50 65 80 95 110 125 2.7 3.05 3.4 3.75 Ambient Temperature (oC) FIGURE 2-1: FIGURE 2-4: 4.8 5.15 5.5 IQ vs. Input Voltage. 100 VOUT = 1.2V 95 IOUT = 100 mA 90 85 80 IOUT = 300 mA 75 VIN = 3.6V 90 Efficiency (%) Efficiency (%) 4.45 Input Voltage (V) IQ vs. Ambient Temperature. 100 IOUT = 500 mA 70 80 VIN = 3.0V 70 60 50 40 VIN = 4.2V 30 65 3.0 3.2 3.4 3.6 3.8 4.0 VOUT = 1.2V 20 4.2 0.1 1 Input Voltage (V) FIGURE 2-2: (VOUT = 1.2V). Efficiency vs. Input Voltage 1000 Efficiency vs. Output Load 100 VOUT = 1.8V 90 85 IOUT = 300 mA IOUT = 500 mA 80 VIN = 3.6V 90 IOUT = 100 mA 75 Efficiency (%) 95 10 100 Output Current (mA) FIGURE 2-5: (VOUT = 1.2V). 100 Efficiency (%) 4.1 80 70 VIN = 3.0V 60 50 40 VIN = 4.2V 30 70 3.0 3.2 3.4 3.6 3.8 4.0 4.2 VOUT = 1.8V 20 0.1 Input Voltage (V) FIGURE 2-3: (VOUT = 1.8V). Efficiency vs. Input Voltage © 2007 Microchip Technology Inc. 1 10 100 1000 Output Current (mA) FIGURE 2-6: (VOUT = 1.8V). Efficiency vs. Output Load DS22061A-page 7 MCP1602 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. 100.0 100 VOUT = 3.3V IOUT = 100 mA 95.0 IOUT = 300 mA 92.5 90.0 VIN = 4.2V 90 Efficiency (%) Efficiency (%) 97.5 IOUT = 500 mA 87.5 80 70 60 50 40 30 85.0 VIN = 5.5V 4.2 4.4 4.6 4.8 5.0 5.2 5.4 0.1 1 Input Voltage (V) FIGURE 2-7: (VOUT = 3.3V). Efficiency vs. Input Voltage FIGURE 2-10: (VOUT = 3.3V). 100 1000 Efficiency vs. Output Load 96 PG Threshold (% of V OUT ) PG Active Time-Out (ms) 10 Output Current (mA) 340 320 300 280 260 240 220 200 95 PG Threshold High 94 93 92 91 90 PG Threshold Low 89 88 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 Ambient Temperature (°C) 5 20 35 50 65 80 95 110 125 Ambient Temperature (°C) FIGURE 2-8: PG Active Time-out vs. Ambient Temperature. FIGURE 2-11: PG Threshold Voltage vs. Ambient Temperature. 1.85 0.832 0.828 Output Voltage (V) Feedback Voltage (V) VOUT = 3.3V 20 0.824 0.820 0.816 Ambient Temperature (°C) FIGURE 2-9: Feedback Voltage vs. Ambient Temperature. DS22061A-page 8 125 95 110 80 65 50 35 5 20 -10 -25 -40 0.812 1.84 1.83 1.82 1.81 0 50 100 150 200 250 300 350 400 450 500 Output Current (mA) FIGURE 2-12: Output Voltage vs. Load Current (VOUT = 1.8V). © 2007 Microchip Technology Inc. MCP1602 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. Switching Frequency (MHz) Switching Frequency (MHz) 2.00 1.98 1.96 1.94 1.92 1.90 -40 -25 -10 5 20 35 50 65 80 95 110 125 Ambient Temperature (°C) FIGURE 2-13: Switching Frequency vs. Ambient Temperature. 2.05 2.00 1.95 1.90 1.85 2.70 3.05 3.40 3.75 4.10 4.45 4.80 5.15 5.50 Input Voltage (V) FIGURE 2-16: Input Voltage. 0.6 Switching Frequency vs. 0.7 0.5 P-Channel 0.4 N-Channel 0.3 0.2 2.70 3.05 3.40 3.75 4.10 4.45 4.80 5.15 5.50 Switch Resistance (Ω) Switch Resistance (Ω) 2.10 0.6 0.5 P-Channel 0.4 N-Channel 0.3 0.2 -40 -25 -10 5 20 35 50 65 80 95 110 125 Ambient Temperature (°C) Input Voltage (V) 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 DS22061A-page 9 MCP1602 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 2-20: Output Voltage Load Step Response vs. Time. DS22061A-page 10 FIGURE 2-21: Output Voltage Line Step Response vs. Time. FIGURE 2-22: Power-Good Output Timing. © 2007 Microchip Technology Inc. MCP1602 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE MSOP DFN Sym 1 1 SHDN 2 2 VCC Analog Input Supply Voltage Pin 3 3 PG Power Good Output Pin 4 4 AGND 5 5 VFB/VOUT 6 6 VIN Input Supply Voltage Pin 7 7 LX Buck Inductor Output Pin 8 8 PGND — Exposed Pad EP 3.1 Description Shutdown Input Pin Analog Ground Pin Feedback Voltage (Adjustable Version) / Output Voltage (Fixed Version) Pin Power Ground Pin 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 AGND Shutdown Control Input Pin (SHDN) 3.6 Power Supply Input Voltage Pin (VIN) 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. VIN is the buck regulator power input supply pin. Connect a variable input voltage source to VIN. 3.2 Connect LX directly to the buck inductor. This pin carries large signal-level current; all connections should be made as short as possible. Analog Input Supply Voltage Pin (VCC) The VCC pin provides bias for internal analog functions. This voltage is derived by filtering the VIN supply. 3.3 Power-Good Output Pin (PG) PG is an output level indicating that the output voltage is within 94% of regulation. The PG output is configured as an open-drain output. 3.4 Analog Ground Pin (AGND) AGND is the analog ground connection. Tie AGND to the analog portion of the ground plane (AGND). See the physical layout information in the Section 5.8 “PCB Layout Information” section for ground recommendations. 3.5 3.7 3.8 Buck Inductor Output Pin (LX) Power Ground Pin (PGND) Connect all large signal level ground returns to PGND. These large signal level ground traces should have a small loop area and length to prevent coupling of switching noise to sensitive traces. 3.9 Exposed Metal Pad (EP) For the DFN package, connect the Exposed Pad to AGND, with vias into the AGND plane. This connection to the AGND plane will aid in heat removal from the package. Output Voltage Sense Pin (VFB/ VOUT) For the adjustable output voltage options, connect the center of the output voltage divider to the VFB pin. For fixed-output voltage options, connect the output of the buck regulator to this pin (VOUT). © 2007 Microchip Technology Inc. DS22061A-page 11 MCP1602 4.0 DETAILED DESCRIPTION 4.1 Device Overview The MCP1602 is a synchronous buck regulator with a power-good signal. The device 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 MCP1602 can deliver 500 mA of continuous output current. When using the MCP1602, 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 (typical) 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 MCP1602 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 switches between PWM mode and PFM mode depending upon the output load requirements. 4.2.1 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 MCP1602 operates in a PFM mode. When the MCP1602 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 4.3 Power-Good (PG) The open-drain power-good (PG) circuitry monitors the regulated output voltage. A fixed delay time of approximately 262 ms is generated once the output voltage is above the power-good high threshold, VTH_H, (typically 94% of VOUT). As the output voltage falls below the power-good low threshold, VTH_L, (typically 92% of VOUT) the PG signal transitions to a low state indicating that the output is out of regulation. The PG circuitry has a typical 165 µs delay when detecting a falling output voltage. This helps to increase the noise immunity of the power-good output, avoiding false triggering of the PG signal during line and load transients. FIXED FREQUENCY, PWM MODE During heavy load conditions, the MCP1602 operates at a high, fixed switching frequency of 2.0 MHz (typical). 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 sensed output voltage. When the sensed current becomes equal to the amplified error signal, the high-speed 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. DS22061A-page 12 VTH_H VTH_L VOUT tRPU tRPD PG FIGURE 4-1: VOH VOL Power-Good Timing. © 2007 Microchip Technology Inc. MCP1602 4.4 Soft Start The output of the MCP1602 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. 4.5 Overtemperature Protection Overtemperature protection circuitry is integrated in the MCP1602. This circuitry monitors the device junction temperature and shuts the device off if the junction temperature exceeds the typical 150oC threshold. If this threshold is exceeded, the device will automatically restart once the junction temperature drops by approximately 10oC. The soft start is reset during an overtemperture condition. 4.6 Overcurrent Protection Cycle-by-cycle current limiting is used to protect the MCP1602 from being damaged when an external short circuit is applied. The typical peak current limit is 700 mA. If the sensed current reaches the 700 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. 4.7 Enable/Disable Control The SHDN pin is used to enable or disable the MCP1602. 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. 4.8 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 MCP1602, 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 200 mV. DS22061A-page 13 MCP1602 5.0 APPLICATION INFORMATION 5.1 Typical Applications The MCP1602 synchronous buck regulator with powergood 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 to 5V regulated input applications. 5.2 Fixed Output Voltage Applications The Typical Application Circuit shows a fixed MCP1602 in a typical application used to convert three NiMH batteries into a well regulated 1.5V @ 500 mA output. A 4.7 µF input and output capacitor, a 4.7 µH inductor, and a small RC filter make up the entire external component selection for this application. No external voltage divider or compensation is necessary. In addition to the fixed 1.5V option, the MCP1602 is also available in 1.2V, 1.8V, 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 MCP1602 can be used. The circuit listed in Figure 6-2 shows an adjustable MCP1602 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 = VOUT = VFB 200 kΩ 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 a RMS current rating given by Equation 5-2. 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 it also 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. 1.0V 0.8V RBOT = 200 kΩ x (0.8V/(1.0V - 0.8V)) RBOT = 800 kΩ (Standard Value = 787 kΩ) DS22061A-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: EQUATION 5-3: ΔI L ΔV OUT = ΔI L × ESR + -------------------8×f×C © 2007 Microchip Technology Inc. MCP1602 Table 5-1 contains the recommend range for the output capacitor value. TABLE 5-1: CAPACITOR VALUE RANGE CIN COUT Minimum 4.7 µF 4.7 µF Maximum — 22 µF 5.6 Inductor Selection For most applications an inductor value of 4.7 µH is recommended to achieve a good balance between converter load transient response and minimized noise. There are many different magnetic core materials and package options to select from. That decision is based on size, cost, and acceptable radiated energy levels. Toroid and shielded ferrite pot cores will have low radiated energy, but tend to be larger and higher in cost. 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 Equation 5-4. 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: MCP1602 RECOMMENDED INDUCTORS Value (µH) DCR Ω (max) ISAT (A) Size WxLxH (mm) SD10 3.3 0.108 1.31 5.2x5.2x1.0 SD10 4.7 0.154 1.08 5.2x5.2x1.0 SD10 6.2 0.218 0.92 5.2x5.2x1.0 SD12 3.3 0.104 1.42 5.2x5.2x1.2 Part Number TABLE 5-2: Part Number MCP1602 RECOMMENDED INDUCTORS (CONTINUED) Value (µH) DCR Ω (max) ISAT (A) Size WxLxH (mm) Wurth Elektronik® WE-TPC Type S 3.6 0.085 1.10 3.8x3.8x1.65 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 WE-TPC Type M 3.3 0.065 1.80 4.8x4.8x1.8 WE-TPC Type M 4.7 0.082 1.65 4.8x4.8x1.8 WE-TPC Type M 6.8 0.100 1.25 4.8x4.8x1.8 5.7 Thermal Calculations The MCP1602 is available in two different packages (MSOP and 3x3 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 MCP1602 is +125oC. 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 Dis ⎝ 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 MCP1602. There is some percentage of power lost in the buck inductor, with very little loss in the input and output capacitors. Coiltronics® SD12 4.7 0.118 1.29 5.2x5.2x1.2 SD12 6.2 0.170 1.08 5.2x5.2x1.2 © 2007 Microchip Technology Inc. DS22061A-page 15 MCP1602 5.8 PCB Layout Information components along the high current path should be placed as close as possible to the MCP1602 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. Therefore, it is important that the 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. 4.7 µH VIN 2.7V to 4.5V 4.7 µF LX 7 6 VIN 10Ω 2 VCC 4 AGND 0.1 µF 1 SHDN VOUT 1.5V @ 500 mA 4.7 µF VFB 5 PGND 8 PG 3 MCP1602 RPULLUP Processor Reset ON OFF VIN FIGURE 5-1: DS22061A-page 16 PCB High Current Path. © 2007 Microchip Technology Inc. MCP1602 6.0 TYPICAL APPLICATION CIRCUITS l VIN 3.0V to 4.2V 4.7 µF 10Ω 0.1 µF 4.7 µH 6 VIN LX 7 2 VCC VFB 5 4 AGND PGND 8 1 SHDN PG 3 MCP1602 VOUT 1.5V @ 500 mA 4.7 µF RPULLUP Processor Reset ON OFF VIN FIGURE 6-1: VIN 5.0V 4.7 µF Single Li-Ion to 1.5V @ 500 mA Application. 10Ω 0.1 µF LX 7 VCC VOUT 5 4 AGND PGND 8 1 SHDN PG 3 6 VIN 2 4.7 µH RTOP 200 kΩ ON 4.7 µF RBOT 787 kΩ MCP1602 RPULLUP OFF RCOMP 4.99 kΩ CCOMP 33 pF VOUT 1.0V @ 500 mA Processor Reset VIN FIGURE 6-2: 5V to 1.0V @ 500 mA Application. VIN 2.7V to 4.5V 4.7 µF 10Ω 0.1 µF 4.7 µH 6 VIN LX 7 2 VCC VFB 5 4 AGND PGND 8 1 SHDN PG 3 MCP1602 VOUT 1.2V @ 500 mA 4.7 µF RPULLUP Processor Reset ON OFF VIN FIGURE 6-3: 3 NiMH Batteries to 1.2V @ 500 mA Application. © 2007 Microchip Technology Inc. DS22061A-page 17 MCP1602 7.0 PACKAGING INFORMATION 7.1 Package Marking Information 8-Lead DFN (3x3) XXXX XYWW NNN Part Number Code MCP1602-120I/MF CAAU MCP1602-150I/MF CAAV MCP1602-180I/MF CAAW MCP1602-250I/MF CAAY MCP1602-330I/MF CAAZ MCP1602-ADJI/MF CAAS 8-Lead MSOP XXXXXX YWWNNN Legend: XX...X Y YY WW NNN e3 * Note: DS22061A-page 18 Example: CAAU 0733 256 Example: Part Number Code MCP1602-120I/MF 160212 MCP1602-150I/MF 160215 MCP1602-180I/MF 160218 MCP1602-250I/MF 160225 MCP1602-330I/MF 160233 MCP1602-ADJI/MF 1602AJ 1602AJ 733256 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. MCP1602 8-Lead Plastic Dual Flat, No Lead Package (MF) – 3x3x0.9 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 EXPOSED PAD E E2 K NOTE 1 1 2 D2 2 NOTE 1 1 BOTTOM VIEW TOP VIEW A NOTE 2 A3 A1 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 Overall Length D Exposed Pad Width E2 Overall Width E Exposed Pad Length 0.65 BSC 0.20 REF 3.00 BSC 0.00 – 1.60 3.00 BSC D2 0.00 – Contact Width b 0.25 0.30 0.35 Contact Length L 0.20 0.30 0.55 Contact-to-Exposed Pad K 0.20 – 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. 2.40 – Microchip Technology Drawing C04-062B © 2007 Microchip Technology Inc. DS22061A-page 19 MCP1602 8-Lead Plastic Micro Small Outline Package (MS) [MSOP] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging D N E E1 NOTE 1 1 2 e b A2 A c φ L L1 A1 Units Dimension Limits Number of Pins MILLIMETERS MIN N NOM MAX 8 Pitch e Overall Height A – 0.65 BSC – Molded Package Thickness A2 0.75 0.85 0.95 Standoff A1 0.00 – 0.15 Overall Width E Molded Package Width E1 3.00 BSC Overall Length D 3.00 BSC Foot Length L Footprint L1 1.10 4.90 BSC 0.40 0.60 0.80 0.95 REF Foot Angle φ 0° – 8° Lead Thickness c 0.08 – 0.23 Lead Width b 0.22 – 0.40 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 C04-111B DS22061A-page 20 © 2007 Microchip Technology Inc. MCP1602 APPENDIX A: REVISION HISTORY Revision A (October 2007) • Original Release of this Document. © 2007 Microchip Technology Inc. DS22061A-page 21 MCP1602 NOTES: DS22061A-page 22 © 2007 Microchip Technology Inc. MCP1602 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. X Device Tape & Reel -XXX X Voltage Temp. Output Range XX Package Examples: a) b) c) Device MCP1602: 2.0 MHz, 500 mA, Buck Reg w/Power-Good Tape & Reel T = Tape and Reel Blank = Tube d) 120 = 1.20V 150 = 1.50V 180 = 1.80V 250 = 2.50V 330 = 3.30V ADJ = Adjustable Voltage Version (0.8V to 4.5V) f) * Custom output voltages available upon request. Contact your local Microchip sales office for more information. i) Standard Fixed Output Voltage * e) g) h) j) Temperature Range I = -40°C to +85°C k) Package * MF = Plastic Dual Flat No Lead, (3x3 mm Body), 8-Lead MS = Plastic Micro Small Outline, 8-Lead © 2007 Microchip Technology Inc. l) MCP1602-1202I/MF: 1.20V, 500 mA Buck Reg, 8LD DFN Pkg. MCP1602-1202I/MS: 1.20V, 500 mA Buck Reg, 8LD MSOP Pkg. MCP1602-1502I/MF: 1.50V, 500 mA Buck Reg, 8LD DFN Pkg. MCP1602-1502I/MS: 1.50V, 500 mA Buck Reg, 8LD MSOP Pkg. MCP1602-1802I/MF: 1.80V, 500 mA Buck Reg, 8LD DFN Pkg. MCP1602-1802I/MS: 1.80V, 500 mA Buck Reg, 8LD MSOP Pkg. MCP1602-2502I/MF: 2.50V, 500 mA Buck Reg, 8LD DFN Pkg. MCP1602-2502I/MS: 2.50V, 500 mA Buck Reg, 8LD MSOP Pkg. MCP1602T-3302I/MF: Tape and Reel, 3.30V, 500 mA Buck Reg, 8LD DFN Pkg. MCP1602-3302I/MS: 3.30V, 500 mA Buck Reg, 8LD MSOP Pkg. MCP1602-ADJI/MF: Adjustable, 500 mA Buck Reg, 8LD DFN Pkg. MCP1602-ADJI/MS: Adjustable, 500 mA Buck Reg, 8LD MSOP Pkg. DS22061A-page 23 MCP1602 NOTES: DS22061A-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, dsSPEAK, 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. 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