MCP1643T-I/MSVAO

MCP1643 1 MHz Low Start-up Voltage Synchronous Boost LED Constant Current Regulator Features Description • 1.6A Typical Peak Input Current Limit • Up to 550 mA LED Load Current • Low Start-up Voltage: 0.65V (typical, 25 mA LED Current) • Low Operating Input Voltage: down to 0.5V • Maximum Input Voltage < VLED < 5.0V • Maximum Output Voltage: - 5.0V - Overvoltage Protection • Low Reference Voltage: - VFB = 120 mV - Minimal Power Loss on Sense Resistor • Pulse-Width Modulation Mode Operation (1 MHz) • Internal Synchronous Rectifier • Internal Compensation • Inrush Current Limiting • Internal Soft-Start (240 µs typical) • Shutdown (EN = GND): - True Load Disconnect - Dimming Control by Variable Duty Cycle • Shutdown Current: 1.2 µA (typical) • Overtemperature protection • Packages: - MSOP-8 - 2x3 DFN-8 MCP1643 is a compact, high-efficiency, fixed frequency, synchronous step-up converter optimized to drive one LED with constant current, that operates from one and two-cell alkaline and NiMH/NiCd batteries. The device can also drive two red/green/yellow series connection LEDs. Applications • One and Two Cell Alkaline and NiMH/NiCd Portable LED Lighting Products • LED Flashlight and Head Lamps • Rechargeable Flashlights • Wall LED Lamps with Motion Detectors • LED supply for backlights • General LED constant current applications Low-voltage technology allows the regulator to start up without high-output voltage and load-current overshoot from a low 0.65V input. High efficiency is accomplished by integrating the low resistance N-Channel Boost switch and synchronous P-Channel switch. All compensation and protection circuitry are integrated to minimize external components. The internal feedback (VFB) voltage is set to 120 mV for low power dissipation when sensing and regulating LED current. A single resistor sets the constant current output that drives the LED load. The device features an output overvoltage protection that limits the output voltage to 5.0V typical, in case the LED fails or output load is disconnected. The LED will either be turned OFF or turned ON using the enable input. A True Output Load Disconnect mode provides input-to-output isolation while Shutdown (EN = GND) by removing the normal boost regulator diode path from input to output. Shutdown state consumes 1.2 µA from input at room temperature. The LED can be turned on and off with a variable duty cycle pulse-width modulation (PWM) signal applied to the EN pin for dimming applications. The device also features a thermal shutdown at +150°C, with +25°C hysteresis. Two package options, MSOP-8 and 2x3 DFN-8, are available. Package Types MCP1643 MSOP-8 EN 1 VFB 2 NC 3 VOUT 4 MCP1643 2x3 DFN* 8 VIN EN 1 7 SGND VFB 2 NC 3 6 PGND VOUT 4 5 SW 8 VIN EP 9 7 SGND 6 PGND 5 SW * Includes Exposed Thermal Pad (EP), see Table 3-1.  2013 Microchip Technology Inc. DS20005208A-page 1 MCP1643 Typical Applications L1 4.7 µH I CIN 4.7...10 µF LED ILED = 25 mA SW VOUT VIN 0.12V = ----------------R SET LED COUT 4.7 µF MCP1643 ALKALINE + VFB EN - RSET 4.7 GND ON L1 4.7 µH OFF CIN 4.7...10 µF SW VOUT VIN REN 1 M NIMH 1.2V + WHITE LED ILED = 360 mA COUT 20 µF MCP1643 VFB EN - RSET 0.33 GND ON/OFF NIMH 1.2V + - RSET Minimum and Maximum Limits for ILED in Regulation, with ±6% Tolerance 10 1000 ILED MAX ILED MAX 1 100 RSET for ILED MAX ILED MIN ILED MIN WHITE LED TA = +25oC 0.1 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 LED Current (mA) RSET (Ω) RSET for ILED MIN 10 3 Input Voltage (V) DS20005208A-page 2  2013 Microchip Technology Inc. MCP1643 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 † EN, FB, VIN, VSW, VOUT - GND ........................... +6.5V EN, FB ......... < maximum VOUT or VIN > (GND – 0.3V) Output Short Circuit Current....................... Continuous Power Dissipation ............................ 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 DC CHARACTERISTICS Electrical Characteristics: Unless otherwise indicated, VIN = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH, ILED = 25 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C. Parameters Sym Min Typ Max Units Conditions Minimum Input Voltage After Start-Up VIN — 0.5 — V Note 1, Note 3 Start-Up Voltage VIN — 0.65 0.8 V Note 2, Note 1 Output Overvoltage Protection VOUT_OVP — 5.0 — V Note 3 Shutdown Quiescent Current IQSHDN — 1.2 — µA EN = GND; includes N-Channel and P-Channel Switch Leakage Feedback Voltage VFB 105 120 135 mV Feedback Input Bias Current IVFB — 60 — pA NMOS Switch Leakage INLK — 0.4 — µA VIN = VSW = 4.0V VOUT = 4.5V VEN = VFB = GND PMOS Switch Leakage IPLK — 0.25 — µA VIN = VSW = GND; VOUT = 4.5V NMOS Switch ON Resistance RDS(ON)N — 0.2 —  ILED = 250 mA, Note 3 PMOS Switch ON Resistance RDS(ON)P — 0.4 —  ILED = 250 mA, Note 3 NMOS Peak Switch Current Limit IN(MAX) — 1.6 — A Note 3 Maximum Duty Cycle DCMAX — 90 — % Note 3 Minimum Duty Cycle DCMIN — 5 — % Note 3 Switching Frequency fSW 0.85 1.0 1.15 EN Input Logic High VIH 75 — — EN Input Logic Low VIL — — 20 Input Characteristics Note 1: 2: 3: MHz %of VIN ILED= 25 mA %of VIN ILED = 25 mA For VIN < VOUT, ILED remains in regulation up to VIN = VLED minus a headroom @ LED typical VF and IF. VOUT completely discharged. If the output capacitor remains partially charged, the device will start-up at the minimum possible voltage. Determined by characterization, not production tested.  2013 Microchip Technology Inc. DS20005208A-page 3 MCP1643 DC CHARACTERISTICS (CONTINUED) Electrical Characteristics: Unless otherwise indicated, VIN = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH, ILED = 25 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C. Parameters Sym Min Typ Max Units EN Input Leakage Current IENLK — 0.9 — µA VEN = 1.2V tSS — 240 — µs EN Low-to-High, 90% of VOUT; ILED = 25 mA, Note 3 — 270 — µs EN Low-to-High, 90% of VOUT; ILED = 300 mA, Note 3 TSD — 150 — C ILED= 25 mA TSDHYS — 25 — C Soft Start Time Thermal Shutdown Die Temperature Die Temperature Hysteresis Note 1: 2: 3: Conditions For VIN < VOUT, ILED remains in regulation up to VIN = VLED minus a headroom @ LED typical VF and IF. VOUT completely discharged. If the output capacitor remains partially charged, the device will start-up at the minimum possible voltage. Determined by characterization, not production tested. TEMPERATURE SPECIFICATIONS Electrical Characteristics: Unless otherwise indicated, VIN = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH, ILED = 25 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C. Parameters Sym Min Typ Max Units Conditions Temperature Ranges Operating Ambient Temperature Range TA -40 — +85 °C Storage Temperature Range TA -65 — +150 °C Maximum Junction Temperature TJ — — +150 °C Thermal Resistance, 8L-2x3 DFN JA — 68 — °C/W Thermal Resistance, 8L-MSOP JA — 211 — °C/W Steady State Transient Package Thermal Resistances DS20005208A-page 4  2013 Microchip Technology Inc. MCP1643 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 = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH, ILED = 25 mA, TA = +25°C, MSOP-8 package. LED Current (mA) 450 100 LED VF = 3.5V @ IF = 700 mA 95 RSET = 0.25ȍ 400 Efficiency (%) 500 350 RSET = 0.41ȍ 300 250 200 RSET = 0.82ȍ 150 100 50 0.9 FIGURE 2-1: RSET = 5ȍ 65 1.2 1.5 1.8 Input Voltage (V) 2.1 2.4 One White LED ILED vs. VIN. 10 FIGURE 2-4: vs. ILED. 100 ILED (mA) 1000 One White LED Efficiency 100 LED VF = 2.5V @ IF = 350 mA 95 200 175 Efficiency (%) LED Current (mA) VIN = 1.8V VIN = 1.2V 75 70 RSET = 0.82ȍ 150 125 RSET = 1.2ȍ 100 75 50 RSET = 5ȍ 25 90 VIN = 2.4V VIN = 1.8V 85 VIN = 1.2V 80 75 0 70 0.6 0.7 0.8 0.9 1 1.1 1.2 Input Voltage (V) 1.3 1.4 1.5 One Red LED ILED vs. VIN. FIGURE 2-2: 10 FIGURE 2-5: ILED. 350 100 ILED (mA) 1000 One Red LED Efficiency vs. 100 LED VF = 2.5V @ IF = 350 mA 300 95 RSET = 0.41ȍ 90 Efficiency (%) LEDs Current (mA) 80 60 0.6 225 VIN = 2.4V 85 RSET = 1.2ȍ 0 250 90 250 200 RSET = 0.82ȍ 150 RSET = 1.2ȍ 100 VIN = 3.6V 85 80 75 VIN = 2.4V VIN = 3.0V 70 65 60 50 RSET = 5ȍ 55 0 50 0.6 0.9 1.2 1.5 1.8 Input Voltage (V) 2.1 2.4 FIGURE 2-3: Two Series Connection Red LEDs ILED vs. VIN.  2013 Microchip Technology Inc. 10 100 ILED (mA) 1000 FIGURE 2-6: Two Red LEDs Efficiency (in Series Connection) vs. ILED. DS20005208A-page 5 MCP1643 Note: Unless otherwise indicated, VIN = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH, ILED = 25 mA, TA = +25°C, MSOP-8 package. 700 350 TA = +85oC VIN = 1.5V 250 200 RSET = 0.82ȍ 150 RSET = 1.2ȍ 100 50 400 TA = 0oC 300 200 0 -40 -25 -10 5 20 35 50 65 Ambient Temperature (°C) FIGURE 2-7: Temperature. 0.6 80 One White ILED vs. Ambient 150 0.9 1.2 1.5 1.8 2.1 Input Voltage (V) 2.4 2.7 3 Maximum ILED vs. VIN. FIGURE 2-10: 1010 VIN = 1.5V RSET = 0.82ȍ 125 Switching Frequency (kHz) LED Current (mA) 500 100 RSET = 5ȍ 0 1005 100 1000 75 50 fEN = 400 Hz fEN = 1 kHz 25 0 995 990 985 ILED = 100 mA 980 0 10 20 30 40 50 60 Duty Cycle (%) FIGURE 2-8: 70 80 90 100 ILED vs. VEN Duty Cycle. -40 -25 -10 5 20 35 50 65 Ambient Temperature (°C) FIGURE 2-11: Temperature. 40 80 fSW vs. Ambient 123 RSET = 1.2ȍ (ILED = 100 mA) 122 Feadback Voltage (mV) 39 Duty Cycle (%) TA = +25oC 600 RSET = 0.41ȍ LED Current (mA) LED Current (mA) 300 38 37 36 35 121 120 119 118 ILED = 100 mA 117 34 -40 -25 -10 5 20 35 50 65 Ambient Temperature (°C) FIGURE 2-9: Temperature. DS20005208A-page 6 80 Duty Cycle vs. Ambient -40 -25 FIGURE 2-12: Temperature. -10 5 20 35 50 65 Ambient Temperature (°C) 80 VFB vs. Ambient  2013 Microchip Technology Inc. MCP1643 Note: Unless otherwise indicated, VIN = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH, ILED = 25 mA, TA = +25°C, MSOP-8 package. ILED 20 mA/div ILED 20 mA/div VIN 1 V/div VIN 1 V/div VEN 80 us/div FIGURE 2-13: Start-up After Enable. IL 500 mA/div 80 us/div FIGURE 2-16: Start-up when VIN = VEN. VOUT 20 mV/div, AC Coupled ILED 50 mA/div VSW 1 V/div VSW 1 V/div ILED 100 mA/div VEN 1 V/div 400 us/div 1 us/div FIGURE 2-14: 100 mA PWM Operation. ILED 50 mA/div FIGURE 2-17: 15% Duty Cycle. 400 Hz PWM Dimming, VOUT 5V 2 V/div VSW 1 V/div 2V Step from ILED = 100 mA to Open Load ILED 100 mA/div VSW 2 V/div VEN 1 V/div FIGURE 2-15: 85% Duty Cycle. 10 ms/div 400 us/div 400 Hz PWM Dimming,  2013 Microchip Technology Inc. FIGURE 2-18: Open Load Response. DS20005208A-page 7 MCP1643 NOTES: DS20005208A-page 8  2013 Microchip Technology Inc. MCP1643 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE MCP1643 2 x 3 DFN MCP1643 MSOP Symbol 1 1 EN Enable pin. The logic high enables the operation. Do not allow this pin to float. 2 2 VFB Reference Voltage pin. Connect to the VFB pin, the RSET (LED current set resistor), and the cathode of the LED load. 3 3 NC Unconnected pin 4 4 VOUT 5 5 SW 6 6 PGND Power Ground Reference pin 7 7 SGND Signal Ground Reference pin 8 8 VIN Input Supply Voltage pin. A local bypass capacitor is required. 9 — EP Exposed Thermal Pad, must be connected to VSS 3.1 Description Boost Converter Output pin. Connect to this pin the anode of the LED load. An output filter capacitor is required. Boost and Rectifier Switch Input pin. Connect the boost inductor between SW and VIN. Enable Pin (EN) The EN pin is a logic-level input used to enable or disable device switching. Device has low quiescent current while disabled. A logic high (>75% of VIN) will enable the regulator output. A logic low (