NCV887801 Start-Stop Demo Demonstration Note for NCV887801 Automotive Grade High-Frequency Start-Stop Boost Controller Description This NCV887801 demonstration board provides a convenient way to evaluate a high frequency boost controller designed to supply a minimum output voltage during Start-Stop vehicle battery voltage sags. The unit is in low Iq sleep-mode under normal battery operating condition and wakes-up when the monitored voltage drops below 7.3 V and begin regulating once 6.8 V is reached. Switching frequency is 450 kHz. The demo board is rated 6.8 V/3.6 A at a 2.6 V input voltage. Operation below 2.6 V is possible if output current is reduced. http://onsemi.com Key Features • Automatic enable below 7.3V • Disable Override Function • Status Indicator • Boost Operation at 6.8V • 450kHz Switching Frequency • Input Undervoltage Lockout • Wide Input Voltage of 2.6V to 45V • Low Quiescent Current in Sleep Mode (<12µA Typical) • Cycle-by-Cycle Current Limit Protection • Automotive Grade Figure 1. NCV887801 Start-Stop Demo Board 3/27 1 www.onsemi.com Demonstration Board Terminals Terminal Function VIN (connector jack) Positive DC input voltage (power) GND (connector jack) Common DC return (power) VOUT (connector jack) Regulated DC output voltage (power) GND (small post) Common DC return, monitoring point VC (small post) Voltage compensation, monitoring point VOUT (small post) Regulated DC output voltage, monitoring point VDRV (small post) Driving voltage, monitoring point DISB (small post) Disable override input, monitoring point STAT (small post) Status indicator, monitoring point ISNS (small post) Current sense resistor voltage, monitoring point VG (small post) MOSFET gate voltage, monitoring point SW (small post) MOSFET drain voltage, monitoring point Absolute Maximum Ratings (Voltages are with respect to GND) Rating Value Unit DC supply voltage (VIN) -0.3 to 45 V DC voltage (VC, ISNS) -0.3 to 3.6 V -0.3 to 6 V Junction Temperature -40 to 150 °C Ambient temperature (Demo Board) -40 to 105 °C DC Voltage (DISB, STAT) Electrical Characteristics (TA = 25°C, 2.6V ≤ VIN ≤ Vout, VDISB = 5V, unless otherwise specified) Characteristics Conditions Typical Value Unit ROSC = 10.7kΩ 450 kHz - 18 A - 0.83 - VOUT Undervoltage Lockout (UVLO) VOUT falling 3.59 V Thermal Shutdown TA increasing 170 °C Switching Switching Frequency Current Limit Cycle-by-cycle Current Limit (FET) Protections Maximum Duty Cycle 3/27 2 www.onsemi.com Operational Guidelines The demo board is rated to operate under full load for input voltage as low as 2.6V at the input terminal under full power (less if output current is reduced). Start-Stop applications use reverse battery protection diodes in front of the boost converter (Fig. 2), so the input source can operate down to 2.6V plus a diode drop (i.e ~3V). Notes: a. The IC UVLO (undervoltage lockout) is 4.05V for VOUT rising, 3.59V for VOUT falling (0.54V hysteresis). b. Limit time spent with the power supply operating at minimum input voltage (equivalent to VIN = 2.6V) to avoid overheating the power semiconductors. First Time Power-Up: 1. Connect a DC source voltage (15A capable) set to a voltage of 12-13V as shown in Fig. 1. 2. Connect the DISB TTL control signal as shown in Fig. 1. The initial DISB state should be set to logic-‘0’. 3. Connect a 3.6A constant current load on the output. 4. Decrease the DC input voltage until the PCB VIN voltage is 5.5V + 0.5V. 5. Set the DISB control signal to a TTL high state (i.e. 5V). 6. Verify that the unit is regulating at VOUT = 6.8V. 7. Reduce the DC input voltage until the PCB VIN = 2.6V. Verify that the unit is regulating at VOUT = 6.8V. Start-Stop Voltage Transient Test: 1. Connect both DC1 and DC2 input power supplies as illustrated in Fig. 2. Adjust DC2 so that PCB VIN = 2.6V for a 3.6A load. 2. Connect a 3.6A load on the output. If a load resistor is used, it is recommended to start from a DC1 input voltage of 8.5-9.0V to avoid overstressing the PCB boost diode (D1, rated 4A). 3. Monitor VOUT. Disconnect supply DC1. VOUT should have a response similar to that of Fig 3. 3/27 3 www.onsemi.com DISB Command (TTL) VOUT GND Reverse Polarity Protection Diode Harness PS2 (30 W capable) DISB VIN 3.6A Constant Current Load NCV887801 6.8V / 3.6A Demo Board PS1 (20 A capable) GND GND Figure 2. Demo Board Connections Typical Performance DC1 is disabled, then re-enabled Figure 3 NCV887801 Demo Board Waveforms - 3/27 DC2 at VIN adjusted to 2.6V (after reverse polarity protection diode) VOUT = 6.8V, IOUT = 3.6A 4 www.onsemi.com Schematic Figure 4. NCV887801 boost 6.8V/3.6A demonstration board schematic 3/27 5 www.onsemi.com Bill of Materials 3/27 6 www.onsemi.com PCB Layout Figure 5. Top View Figure 6. Bottom View 3/27 7 www.onsemi.com Typical performance NCV887801 Efficiency (25C) 95 90 Vin=2.6V Efficiency (%) 85 Vin=2.8V Vin=3.0V Vin=3.2V 80 Vin=4.2V Vin=5.2V Vin=6.2V 75 70 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Output Current (A) Figure 7 NCV887801 Efficiency NCV887801 6.8 V Line Regulation 0.07 0.06 0.05 % Regulation (6.8 V reference) 0.04 0.03 0.02 0.01 .1 Amp 0 1 Amp -0.01 2.5 Amp -0.02 3.6 Amp -0.03 -0.04 -0.05 -0.06 -0.07 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 6.2 Input Voltage (V) Figure 8 NCV887801 Line Regulation 3/27 8 www.onsemi.com NCV887801 6.8V Load Regulation 0.07 0.06 0.05 % regulation (6.8 V reference) 0.04 0.03 0.02 Vin=2.6V 0.01 Vin=2.8V 0 Vin=3.0V -0.01 Vin=3.2V -0.02 Vin=4.2V Vin=5.2V -0.03 Vin=6.2V -0.04 -0.05 -0.06 -0.07 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Iout (A) Figure 9 NCV887801 Load Regulation 3/27 9 www.onsemi.com