SI-8511NVS_11

1-1-3 DC/DC Converter ICs SI-8511NVS Surface-Mount, Synchronous Rectifier Step-down Switching Mode Control ICs ■Features • Surface-mount package (TSSOP24) • High efficiency due to synchronous rectification: 92% (at VIN = 5V, IO = 1A, VO = 2.5V) • Capable of downsize a choke-coil due to IC's high switching frequency (400kHz typ, On Time Control). (Compared with conventional Sanken devices) • Low reference voltage (Vref) of 1.1V. The output voltage is variable from 1.1V to 6V. • High-speed response to a load • Compatible with low ESR capacitors • Soft start and output ON/OFF available • Built-in overcurrent and output-overvoltage protection circuits • PWRGD function to indicate the output voltage status • High precision reference voltage: 1.1V ± 1.2% ■Absolute Maximum Ratings Parameter Control-System DC Input Voltage DC Input Voltage Boost Block Input Voltage EN Terminal Input Voltage PWRGD Terminal Applied Voltage Junction Temperature Storage Temperature Symbol VCC VIN VH VEN VPWRGD Tj Tstg Ratings 7 25 30 VCC 7 +150 –40 to +150 Unit V V V V V °C °C (Ta=25°C) ■Applications • Power supplies for notebook PCs and mobile devices • Onboard local power supplies • OA equipment • For stabilization of the secondary-side output voltage of switching power supplies ■Recommended Operating Conditions Parameter Control System Input Voltage Range Input Voltage Range Output Voltage Range Operating Temperature Range Symbol VCC VIN VO Top Ratings 4.5 to 5.5 3 to 18 1.1 to 6 –20 to +85 Unit V V V °C ■Electrical Characteristics Parameter Dynamic Output Voltage Characteristics Temperature Coefficient of Output Voltage Circuit Current (VCC Terminal) Circuit Current Circuit Current (VIN Terminal) Standby Current 1 (VCC Terminal) Standby Current 2 (VIN Terminal) Undervoltage UVLO Operating Voltage 1 (VCC Terminal) Lockout UVLO Operating Voltage 2 (VIN Terminal) On Time On Time Control High Side Drive Low Side Drive Bootstrap Minimum Off Time REF Terminal Voltage REF Terminal Source Current On Resistance (high side) On Resistance (low side) On Resistance (high side) On Resistance (low side) Bootstrap Voltage Current for Current Limit Detection Soft Start Terminal Current EN Low Level Voltage EN High Level Voltage Protection System EN Bias Level Current PWRGD Good Voltage (high side) PWRGD Good Voltage (low side) PWRGD Low Output Voltage PWRGD Terminal Current PWRGD Leakage Current Symbol VO ∆VO/∆T Iop Iop Istd1 Istd2 Vuvlo1 Vuvlo2 Ton Toff Vref Iref RonHH RonHL RonLH RonLL VH-VLIN Ilim Iss Vcelo Vcehi ICE Vsens Vsens Vpwrgd Ipwrgd Ipwrgd 1.32 0.88 0.4 120 5 0 2.4 4.5 90 5.5 5.5 5.5 5.5 5 100 ± 20 0.8 VCC 5 5.5 110 1.1 3.7 2.5 1.27 0.7 1.2 1.3 100 Ratings min. –1.2% typ. 1.1 ± 0.03 6 1 100 50 4.45 2.9 max. +1.2% Unit V mV/°C mA mA (Ta=25°C unless otherwise specified) Conditions VIN=5V, VCC=5V, VSNS connected to VO, IO=0A VIN=5V, VCC=5V, VSNS connected to VO, IO=0A, Ta=0 to 85°C VCC=5V, EN=H, FADJ:open VIN=5V, EN=H VCC=5V, EN=L VIN=5V, EN=L VIN=5V VCC=5V VCC=5V, VIN=5V, VO=2.5V VCC=5V VCC=5V VCC=5V VH-VLIN=5V VH-VLIN=5V VCC=5V VCC=5V VCC=5V, VIN=5V VCC=5V VCC=5V VCC=5V VCC=5V, EN=5V VCC=5V VCC=5V VCC=5V, Ipwrgd=120µA VCC=5V, Vpwrgd=0.4V Vpwrgd=5V µA µA V V µS µS V µA Ω Ω Ω Ω V µA µA V V µA V V V µA µA 62 ICs SI-8511NVS ■External Dimensions (TSSOP24) 2.0 φ Mirror surface Depth 0.02 to 0.08 A (Unit : mm) 1.0 φ Mirror surface Depth 0.02 to 0.08 5.60±0.1 7.6±0.2 1.90 3.00 (6.4) 1 12 11 ° 0.375 TYP 0.65 0.22+0.1 –0.05 7.80±0.1 7.9±0.2 0.15 –0.05 +0.1 0.12 M A 0.4 11° 1.15±0.05 11° 11 ° 11 ° 24 13 11 ° 1 S 1° 11° 0.10±0.05 Plastic Mold Package Type Flammability: UL94V-0 Product Mass: Approx. 1.36g 0.50±0.2 ° 0 to 10 0.08 S ■Block Diagram (Pin Assignment) VIN + +5V VCC1 ILIM VIN ISEN VCC2 OCP PRE_REG EN H : ON L : OFF EN Vpreg Level Shift VH Latch Buff DRVH VO Synchronous Cont. (Logic) LIN + UVLO Gate Driver OFF Clamp POWER_GOOD H : GOOD L : NG PWRGD Power Good – + Logic Buff DRVL PGND Switching Constant On Time Cont. + COMP – VO VSNS – + OSC SS OVP_SL GND FADJ Open : Change Frequency Short : 400KHz Operation FSET 14 SS 12 SKIP Open : Skip Mode L : No Skip Mode ■Typical Connection Diagram VIN R2 C1 : 10 µ F VCC : 5V D2 : SFPL52 C7 : 0.1 µ F R1 5mΩ R5 10Ω MOS FET Q1, Q2 • Be sure to use logic type MOS FET as Q1 and Q2. If you use a normal power MOS FET type, the ON resistance may not drop to a satisfactory level due to a shortage of VGS. This may deteriorate the efficiency and cause overheating. Diode D1 • Be sure to use a Schottky-barrier diode for D1. If other diodes like fast recovery diodes are used, IC may be destroyed because of the reverse voltage generated by the recovery voltage or ON voltage. Choke coil L1 • If the winding resistance of the choke coil is too high, the efficiency may drop below the rated value. • Take care concerning heat radiation from the choke coil caused by magnetic saturation due to overload or short-circuit load. Capacitor C1, C2 • As large ripple currents flow through C1 and C2, use high-frequency and lowimpedance capacitors suitable for switching mode power supplies. Especially when the impedance of C2 is high, the switching waveform may become abnormal at low temperatures. For C2, do not use a capacitor with an extremely low equivalent series resistance (ESR) such as a ceramic capacitor, which may cause an abnormal oscillation. * To create the optimum operating conditions, place the components as close as possible to each other. 1 2 3 4 C6 0.1 ~ 1 µ F C9 1000 pF 5 6 7 8 VCC R7 47kΩ PWRGD 11 12 R10 2.2kΩ R9 9 10 NC DRVH VH VIN ISEN ILIN SI-8511NVS GND VSNS VO PWRGD REF NC NC LIN DRVL PGND VCC2 OVP_SL VCC1 SS EN SKIP FADJ NC 24 23 22 21 20 19 Q2 R6 10Ω Q1 L1 : 10 µ H VO + D1 SJPJ-L3 C2 : 330 µ F C5 : 4.7 µ F R13 R12 18 C4 : 3.3 µ F VCC EN SKIP R4 47kΩ C3 0.1 µ F 17 C8 : 220pF 16 15 14 13 R8 : 200kΩ R11 : 100kΩ ICs 63