1-1-2 Switching Mode Regulator ICs SI-8405NL Surface-Mount, Synchronous Rectifier Step-down Switching Mode Regulator Control ICs ■Features ■Absolute Maximum Ratings • Input voltage (Vin): 3.0 to 5.5 V Symbol Ratings Unit • Synchronous rectification Input Voltage (VIN pin) VIN 6 V • Output voltage precision ±1.2% EN/SS Pin Input Voltage VEN –0.3 to VIN V Junction Temperature Tj +125 °C Storage Temperature Tstg –40 to +150 °C • Oscillation Frequency: 250 kHz • Overcurrent protection (Overcurrent value can be set by the external resistor.) • Output can be disabled Parameter ■Recommended Operating Conditions Symbol Ratings Unit Input Voltage Range Parameter VIN 3 to 5.5 V Output Voltage Range VO 0.5 to 4 V Operating Temperature Range Top –40 to +85 °C • Undervoltage Lock Out • Soft start function • High-speed load response ■Applications • Power supply for LCD modules • Power supply for notebook PC • Onboard local power supplies • Power supply for LBP/PPC ■Electrical Characteristics Parameter Reference Voltage Circuit Current (VIN Pin) Standby Current (VIN Pin) (Ta=25°C) Symbol Vref Ratings min. 0.494 Conditions High Side Drive Block ON Resistance (Pulled Up) High Side Drive Block ON Resistance (Pulled Down) Low Side Drive Block ON Resistance (Pulled Up) Low Side Drive Block ON Resistance (Pulled Down) Overcurrent Detection Voltage EN/SS Pin Current EN/SS Low Level Voltage Iop 80 ICs 0.506 Conditions VIN=5V, VEN=H Conditions VIN=5V, VEN=L Conditions VIN=5V, Vo=2.5V Istd 400 RonHH 3.5 Conditions 3.5 Conditions Conditions 50 60 VIN=5V 7 Conditions Vcelo Ω VIN=5V, ID=0.1A 40 Iss Ω VIN=5V, ID=0.1A RonLL Vlim Ω VIN=5V, ID=0.1A RonLH 10 13 VIN=5V 0 Conditions 0.8 VIN=5V 0.8 Conditions 0.9 1.0 VIN=5V Vth(ON) 2.4 VIN=5V Vuvloh 2.9 2.4 µA Ω 3.5 Conditions V µS VIN=5V, ID=0.1A RonHL Vuvlol 600 3.5 Conditions Unit mA 2 Conditions Undervoltage Lock Out (VIN) 0.500 5 Vth(SS Start) EN/SS Threshold Voltage max. VIN=5V, VEN=5V Ton On Time typ. mV µA V V V V V SI-8405NL ■External Dimensions (SOP8) (Unit : mm) 5.1±0.4 1.27 5 1 2 3 4 0.5±0.1 6 6.2±0.3 7 4.4±0.2 8 0~ 10 ° 1.27 1.5±0.1 0.05±0.05 0.10 0.12 M Assignment VIN EN/SS VO VSENS GND DRVL DRVH ISEN Plastic Mold Package Type 1.55±0.15 0.995max. 0.4±0.1 Pin q w e r t y u i 0.15+0.1 –0.05 0.4±0.1 Flammability : UL 94V-0 Product Mass : Approx. 0.1 g ■Block Diagram Vin ISEN UVLO OCP UVLO Synchronous include Dead-time H_DRV H_Side_ Drive DRVH L_DRV L_Side_ Drive DRVL EN SS/EN Gate DRV GND Vo Comp – On-Timing Generator VSNS + + Vref Zep Vref 1 0.5V SS_CON ■Typical Connection Diagram Vin 1 EN 2 C4 Vin SI-8400N EN/SS ISEN C3 DRVH DRVL 4 GND VSNS Vo 3 R2 8 R1 R4 7 Q1 6 Q2 C1 D1 5 Vo L1 + C2 C1 C2 C3 C4 L1 D1 : 10µF : 330µF : 0.022µF : 0.068µF : 10µH : SJPJ-L4 (Sanken) R3 ICs 81