SS6622

SS6620/21/2 High Efficiency Synchronous Step-Up DC/DC Converter n FEATURES l n DESCRIPTION The SS6620/21/22 are high-efficiency stepup DC/DC converters, with start-up voltage as low as 0.8V and operating with an input voltage down to 0.7V. Consuming only 20µA of quiescent current, these devices offer a built-in synchronous rectifier that reduces size and cost by eliminating the need for an external Schottky diode, improving overall efficiency by minimizing losses. The switching frequency depends on the load and the input voltage and can range up to 500KHz. The peak current of the internal switch is fixed at 0.8A (SS6620), at 0.45A (SS6621), or is selectable (SS6622) for design flexibility. Ripple does not exceed the product of the switch current limit and the filter capacitor equivalent-series-resistance (ESR). The SS6622 also features a circuit that eliminates noise caused by inductor ringing. High efficiency of 93% (VIN=2.4V, VOUT=3.3V, IOUT=200mA). Quiescent supply current of 20µA. Power-saving shutdown mode (0.1µA typical). Internal synchronous rectifier (no external diode ) Selectable current limit for reduced ripple (SS6622). Low noise, anti-ringing feature (SS6622) On-chip low-battery detector. Low-battery hysteresis l l l l l l l n APPLICATIONS l l l l l l Palmtop & notebook computers. PDAs Wireless phones Pocket organizers. Cameras. 1 to 2-cell hand-held devices n TYPICAL APPLICATION CIRCUIT VIN + 100µF OFF SHDN SS6620 SS6621 SS6622 LBI REF 0.1µF FB LBO LX OUT 22µH Output 3.3V, or Adj. (1.8V to 4.0V) up to 300mA ON + 220µF Low-Battery Detect In LBO GNDB F Low-Battery Detect Out Rev.2.01 6/06/2003 www.SiliconStandard.com 1 of 12 SS6620/21/2 n ORDERING INFORMATION S S6620CX XX SS6621CX XX SS6622CX XX P ACKING TYPE T R: TAPE & REEL PACKAGING TYPE O: MSOP8 (for SS6620/1) O: MSOP10 (for SS6622) P IN CONFIGURATION ( MSOP8) FB 1 LBI 2 L BO 3 R EF 4 T OP VIEW 8 O UT LX G ND SHDN S S6620 SS6621 7 6 5 ( MSOP10) FB 1 T OP VIEW 1 0 O UT E xample: SS6620COTR à In MSOP8 Package in Tape & Reel L BI 2 L BO 3 C LSEL 4 R EF 5 9 LX S S6622 8 GND 7 BATT 6 SHDN n ABSOLUTE MAXIMUM RATINGS Supply Voltage (OUT to GND) Switch Voltage (LX to GND) Battery Voltage (Batt to GND) SHDN , LBO to GND LBI, REF, FB, CLSEL to GND Switch Current (LX) Output Current (OUT) Operating Temperature Range Storage Temperature Range 8.0V VOUT+ 0.3V 6.0V 6.0V VOUT+0.3V -1.5A to +1.5A -1.5A to +1.5A -40°C ~ +85°C -65°C ~150°C n TEST CIRCUIT Refer to Typical Application Circuit. Rev.2.01 6/06/2003 www.SiliconStandard.com 2 of 12 SS6620/21/2 n ELECTRICAL CHARACTERISTICS (V T A=25°C, unless otherwise specified.) BATT=2.0V, VOUT=3.3V (FB=VOUT), RL=∝, PARAMETER Minimum Input Voltage Operating Voltage Start-Up Voltage Start-Up Voltage Tempco Output Voltage Range Output Voltage TEST CONDITIONS MIN. TYP. 0.7 MAX. UNIT V 1.1 RL=3KΩ (Note1) 0.8 -2 1.8 FB = VOUT 3.17 300 3.3 400 4.0 1.1 V V mV/°C 4.0 3.43 V SS6620 SS6622 Steady State Output Current FB=OUT (CLSEL=OUT) (VOUT =3.3V) SS6621 (Note 2) SS6622 (CLSEL=GND) Reference Voltage Reference Voltage Tempco Reference Load Regulation Reference Line Regulation FB , LBI Input Threshold Internal Switch On-Resistance ILX = 100mA SS6620,SS6622(CLSEL = OUT) LX Switch Current Limit SS6621,SS6622(CLSEL = GND) LX Leakage Current Operating Current into OUT (Note 3) Shutdown Current into OUT Efficiency VOUT = 2V ,ILOAD = 1mA LX Switch On-Time LX Switch Off-Time FB Input Current Rev.2.01 6/06/2003 mA 150 1.199 220 1.23 0.024 1.261 V mV/°C 30 10 1.261 mV mV/V V Ω 1.0 A 0.3 0.45 0.6 µA µA IREF= 0 IREF = 0 to 100 µA VOUT = 1.8V to 4V 1.199 10 5 1.23 0.3 0.6 0.8 VLX=0V, 4V; VOUT=4V VFB = 1.4V , VOUT = 3.3V 0.05 20 1 35 SHDN = GND VOUT= 3.3V ,ILOAD = 200mA 0.1 90 1 µA % 85 2 0.6 4 0.9 0.03 7 1.3 50 µs µs nA VFB =1V , VOUT = 3.3V VFB =1V , VOUT = 3.3V VFB = 1.4V www.SiliconStandard.com 3 of 12 SS6620/21/2 n ELECTRICAL CHARACTERISTICS (Continued) PARAMETER LBI Input Current CLSEL Input Current SHDN Input Current LBO Low Output Voltage LBO Off Leakage Current TEST CONDITIONS VLBI = 1.4V SS6622 , CLSEL = OUT V SHDN = 0 or VOUT VLBI = 0, ISINK = 1mA V LBO = 5.5V, VLBI = 5.5V MIN. TYP. 1 1.4 0.07 0.2 0.07 50 MAX. 50 3 50 0.4 1 UNIT nA µA nA µA LBI Hystereisis Damping Switch Resistance SHDN Input Voltage mV 100 0.2VOUT V Ω SS6622, VBATT = 2V 50 0.8VOUT 0.2VOUT CLSEL Input Voltage 0.8VOUT V Note 1: Start-up voltage operation is guaranteed without the addition of an external Schottky diode between the input and output. Note 2: Steady-state output current indicates that the device maintains output voltage regulation under load. Note 3: Device is bootstrapped (power to the IC comes from OUT). This correlates directly with the actual battery supply. n TYPICAL PERFORMANCE CHARACTERISTICS 100 90 80 160 Input Battery Current (µA) 140 120 100 80 60 40 20 0 Efficiency (%) 70 60 50 40 30 20 10 0 0.01 0.1 1 VIN=2.4V VIN=1.2V I_limit=0.8A , VOUT=3.3V I_limit=0.45A , VOUT =3.3V 0.0 0.5 1.0 1.5 2.0 2.5 3.0 10 100 1000 Loading (mA) Input battery voltage (V) Fig. 1 VOUT=3.3V CLSEL=OUT (0.8A) Fig. 2 No-Load Battery Current vs. Input Battery Voltage Rev.2.01 6/06/2003 www.SiliconStandard.com 4 of 12 SS6620/21/2 n 100 90 TYPICAL PERFORMANCE CHARACTERISTICS 1.8 1.6 (Continued) 80 Start-up Voltage (V) 1.4 1.2 1.0 0.8 0.6 0.4 Efficiency (%) V IN=2.4V 70 Without Diode V IN=1.2V 60 With Diode 50 0.2 40 0.01 0.1 1 10 100 1000 0.0 0.01 0.1 1 10 100 Loading (mA) Fig. 3 V OUT=3.3V CLSEL=GND (0.45A) 0.10 0.08 2.2 2.0 Load Current (mA) Fig. 4 Start-up Voltage vs. Load Current Shutdown Current (µA) 0.06 0.04 0.02 0.00 -0.02 -0.04 -0.06 -0.08 -0.10 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Shutdown Threshold (V) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Fig. 5 800 VOUT (V) Shutdown Current vs. VOUT Output Voltage (V) Fig. 6 Shutdown Threshold vs. Output Voltage Maximum Output Current (mA) 700 600 VOUT=3.3V CLSEL=OUT LX pin waveform 500 400 300 200 VOUT AC Couple CLSEL=GND 100 0 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 Inductor Current VIN=2.4V VOUT=3.3V Input Voltage (V) Fig. 7 Maximum Output Current vs. Input Voltage Fig. 8 Heavy Load Waveform Rev.2.01 6/06/2003 www.SiliconStandard.com 5 of 12 SS6620/21/2 n TYPICAL PERFORMANCE CHARACTERISTICS (Continued) Fig. 9 Without Damping Ringing Function Fig. 10 With Damping Ringing Function VIN=2.4V VOUT=3.3V ∆IOUT=200mA VOUT AC Couple Fig. 11 Load Transient Response Rev.2.01 6/06/2003 www.SiliconStandard.com 6 of 12 SS6620/21/2 n BLOCK DIAGRAM SHDN CLSEL Minimum Off-Time One Shot + Q1 Damping Switch Q3 OUT 0.1µ F BATT LX R1 200Ω L 1 47µF OUT C3 220µF VIN + C1 100µF F/F S R One Shot Maximum On-Time + Q Q2 GND Mirror FB + + LBO Ref erence Voltage REF C4 0.1µ F LBI n PIN DESCRIPTIONS SS6620/ SS6621 PIN 1: FBConnect to OUT for +3.3V output. Use a resistor network to set the output voltage from +1.8V to +4.0V. PIN 2: LBI- Low-battery comparator input. Internally set to trip at +1.23V. PIN 3: LBO- Open-drain low battery comparator output. Output is low when VLBI is