DC / DC converter for LCDs BP5311A / BP5311XA The BP5311A and BP5311XA are DC / DC converters for supplying power to liquid crystal display (LCD) panels. The modules supply a positive voltage for LCDs from a logic circuit power supply (+5). They are available in a single in-line package as an upright (BP5311A) or L-shaped lead (BP5311XA) type. Applications LCD panels in personal computers and word processors. Features 1) High conversion efficiency 2) Built-in protection circuit 3) Built-in ON/OFF switch. 4) Compact and light. 5) Surface mounting is possible because parts are concentrated on one side. 6) Available as an upright or L-shaped lead type. Absolute maximum ratings (Ta=25C) Parameter Symbol Limits Unit Power supply voltage VIN 7V Operating temperature range Topr 0~60 C Storage temperature range Tstg 30~+85 C Block diagram CURRENT TRANSFORMER SENSOR CONTROL SW CTRL CIRCUIT ON / OFF 98 7 4 3 2 1 1/4 VIN VCTL GND GND Vref VOUT Co BP5311A / BP5311XA Pin descriptions Pin No. Pin name Function Output smoothing capacitor connection pin connect a low-impedance capacitor with a recommended 1 Co capacitance of 47 F between this and GND. 2VOUT Output pin. Output voltage adjustment pin for contrast output 3 Vref voltage is adjusted by connecting a resistor between pins 2 and 3 or pins 3 and 4. 4, 7 GND Ground pin. Output ON/OFF control pin output starts when the pin is HIGH level, and stops when the pin is LOW 8 VCTL or OPEN. Input pin connect a low-impedance capacitor with a recommended capacitance of 100 F between 9VIN this pin and GND. Electrical characteristics (unless otherwise noted, Ta=25C, VCTL=5V, R1~R2 resistors are disconnected) Parameter Symbol Min. Typ. Max. Unit Conditions Input voltage VIN 4.5 5.0 5.5 V Output current IOUT 25 mA Output voltage VOUT1 28.0 29.5 31.0 V VIN=4.5~5.5V, IOUT=0~25mA Output voltage when OFF VOUT2 0.3 V VIN=4.5~5.5V, VCTL=0V Ripple noise voltage 1 100 200 mVP-P VIN=5V, IOUT=20mA Efficiency 67 77 % VIN=5V, IOUT=20mA ON / OFF CTL voltage VCTL 1.5 V VIN=5V, Vo>28V when ON 0.5 ON / OFF CTL voltage VCTL V VIN=5V, Vo<0.3V when OFF (Alternatively, when OPEN) ON / OFF CTL current ICTL 500 A VIN=5V, VCTL=1.5V Current consumption IOFF 50 A VIN=5V, VCTL=0V when OFF Measured with a band width of 20 MHz. Measurement circuit / Application example BP5311A / BP5311XA 1 2 3 4 7 8 9 Be sure to use fuse for safety VOUT VIN VCTL R1 R2 + + C2 C1 GND GND C1 : 100 F / 16V (Low impedance) Fig.1 C2 : 47 F / 35V (Low impedance) R1, 2 : Resistors for adjusting output voltage (Contrast adjustment) 2/4