LTC1473L Dual Low Voltage TM PowerPath Switch Driver FEATURES DESCRIPTIO n Power Path Management for Systems The LTC 1473L provides reliable and efficient switching with Multiple DC Sources between two DC power sources. This device drives two n Switches and Isolates Sources from 3.3V to 10V external sets of back-to-back N-channel MOSFET switches n All N-Channel Switching to Reduce Power Losses to route power to the input of a low voltage system. An and System Cost internal boost regulator provides the voltage to fully en- n Built-In Step-Up Regulator for N-Channel Gate Drive hance the logic-level N-channel MOSFET switches while n Capacitor Inrush and Short-Circuit Current Limited an internal undervoltage lock-out circuit keeps the system n User-Programmable Timer Prevents Overdissipation alive down to 2.8V. During Current Limiting The LTC1473L senses current to limit inrush between the n Undervoltage Lockout Prevents Operation with Low batteries and the system supply capacitor during switch- Inputs over transitions or during fault conditions. A user-pro- n Small Footprint: 16-Pin Narrow SSOP grammable timer monitors the time the MOSFET switches are in current limit and latches them off when the pro- U grammed time is exceeded. APPLICATIO S A unique 2-diode logic mode ensures system start-up n Portable Computers regardless of which input receives power first. n Portable Instruments , LTC and LT are registered trademarks of Linear Technology Corporation. n Fault Tolerant Computers PowerPath is a trademark of Linear Technology Corporation. n Battery-Backup Systems n 3.3V/5V Power Management TYPICAL APPLICATIO 3.3V to 4-Cell NiMH Backup Switch Si9926DY DCIN 3.3V LTC1473L 1 16 BAT54C IN1 GA1 LOGIC 2 15 IN2 SAB1 DRIVEN 3 14 V R BAT1 DIODE GB1 SENSE 0.04W 4 NiMH 4 13 3.3V OR + TIMER SENSE V BAT1 5 12 + + V SENSE C OUT 6 11 V GA2 GG 1mH* 7 10 C TIMER 1m F 1m F SW SAB2 2000pF 8 9 GND GB2 1473 TA01 * COILCRAFT 1812LS-105XKBC Si9926DY 1 U ULTC1473L UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW ORDER PART + + SENSE , SENSE , V .................................. 0.3 to 10V IN1 1 16 GA1 NUMBER GA1, GB1, GA2, GB2 ................................... 0.3 to 20V IN2 2 15 SAB1 SAB1, SAB2 .................................................0.3 to 10V DIODE 3 14 GB1 LTC1473LCGN + SW, V ...................................................... 0.3 to 20V TIMER 4 13 SENSE GG + IN1, IN2, DIODE...........................................0.3V to 7V V 5 12 SENSE V 6 11 GA2 Junction Temperature (Note 2)............................. 125 C GG GN PART MARKING SW 7 10 SAB2 Operating Temperature Range ..................... 0 C to 70 C GND 8 9 GB2 Storage Temperature Range ................. 65 C to 150 C 1473L Lead Temperature (Soldering, 10 sec).................. 300 C GN PACKAGE 16-LEAD NARROW PLASTIC SSOP T = 125 C, q = 150 C/ W JMAX JA Consult factory for Military and Industrial grade parts. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating + temperature range, otherwise specifications are at T = 25 C. Test circuit, V = 5V, unless otherwise specified. A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS + V Supply Operating Range 2.8 9 V + I Supply Current V = V = 5V, V = 0V, V = V = 5V l 100 200 m A S IN1 DIODE IN2 SENSE SENSE + + V V Gate Supply Voltage V = V V , 2.8V V 10V (Note 3) l 7.5 8.5 9.5 V GS GS GS GG + + + V V Undervoltage Lockout Threshold V Ramping Down l 2.3 2.5 2.8 V UVLO + + V V Undervoltage Lockout Hysteresis 70 mV UVLOHYS V Digital Input Logic High (Note 4) l 2 0.9 V HIDIGIN V Digital Input Logic Low (Note 4) l 0.6 0.4 V LODIGIN I Input Current V = V = V = 5V 1 m A IN IN1 IN2 DIODE V Gate-to-Source ON Voltage I = I = I = I = 1m A, V = V = 5V l 4.5 5.6 7.0 V GS(ON) GA1 GA2 GB1 GB2 SAB1 SAB2 V Gate-to-Source OFF Voltage I = I = I = I = 100m A, V = V = 5V l 0 0.4 V GS(OFF) GA1 GA2 GB1 GB2 SAB1 SAB2 + + + I SENSE Input Bias Current V = V = 10V (Note 3) l 24.5 10 m A BSENSE SENSE SENSE + V = V = 0V (Note 5) l 300 175 75 m A SENSE SENSE + I SENSE Input Bias Current V = V = 10V (Note 3) l 24.5 10 m A BSENSE SENSE SENSE + V = V = 0V (Note 5) l 300 175 75 m A SENSE SENSE + V Inrush Current Limit Sense Voltage V = 10V (V V ) (Note 3) 0.15 0.20 0.25 V SENSE SENSE SENSE SENSE + V = 0V (V V ) 0.10 0.20 0.30 V SENSE SENSE SENSE + I SAB1, SAB2 Pull-Down Current V = V = V = 0.4V, V = 10V (Note 3) 5 20 35 m A PDSAB IN1 IN2 DIODE V = V = 0.4V, V = 2V 30 140 300 m A IN1 IN2 DIODE I Timer Source Current V = 0.4V, V = V = 2V, V = 0V, l 369 m A TIMER IN1 IN2 DIODE TIMER + V V = 300mV SENSE SENSE V Timer Latch Threshold Voltage V = 0.4V, V = V = 2V l 1.05 1.16 1.25 V TIMER IN1 IN2 DIODE t Gate Drive Rise Time C = 1000pF, V = V = 0V (Note 6) 33 m s ON GS SAB1 SAB2 t Gate Drive Fall Time C = 1000pF, V = V = 5V (Note 6) 2 m s OFF GS SAB1 SAB2 t Gate Drive Turn-On Delay C = 1000pF, V = V = 0V (Note 6) 22 m s D1 GS SAB1 SAB2 t Gate Drive Turn-Off Delay C = 1000pF, V = V = 5V (Note 6) 1 m s D2 GS SAB1 SAB2 f V Regulator Operating Frequency 30 kHz OVGG GS 2 U WWW