LTC1473 TM Dual PowerPath Switch Driver FEATURES DESCRIPTIO n Power Path Management for Systems with Multiple The LTC 1473 provides a power management solution for DC Sources single and dual battery notebook computers and other n All N-Channel Switching to Reduce Power Losses and portable equipment. The LTC1473 drives two sets of back- System Cost to-back N-channel MOSFET switches to route power to the n Switches and Isolates Sources Up to 30V input of the main system switching regulator. An internal n Adaptive High Voltage Step-Up Regulator for N-Channel boost regulator provides the voltage to fully enhance the Gate Drive logic level N-channel MOSFET switches. n Capacitor Inrush and Short-Circuit Current Limited The LTC1473 senses current to limit surge currents both n User-Programmable Timer to Limit Switch Dissipation into and out of the batteries and the system supply n Small Footprint: 16-Pin Narrow SSOP capacitor during switch-over transitions or during fault U conditions. A user-programmable timer monitors the time APPLICATIO S the MOSFET switches are in current limit and latches them off when the programmed time is exceeded. n Notebook Computers n Portable Instruments A unique 2-diode mode logic ensures system start-up n Handi-Terminals regardless of which input receives power first. n Portable Medical Equipment , LTC and LT are registered trademarks of Linear Technology Corporation. PowerPath is a trademark of Linear Technology Corporation. n Portable Industrial Control Equipment TYPICAL APPLICATION MBRD340 Si9926DY BAT1 MMBD2838LTI LTC1473 1 16 IN1 GA1 FROM POWER 2 15 DCIN MANAGEMENT IN2 SAB1 m P 3 14 R DIODE GB1 SENSE INPUT OF SYSTEM 0.04W 4 13 HIGH EFFICIENCY DC/DC + TIMER SENSE SWITCHING REGULATOR 5 12 C TIMER + (LTC1735, ETC) V SENSE C 4700pF OUT 6 11 V GA2 1m F GG 1mH* 7 10 1m F SW SAB2 8 9 GND GB2 MMBD914LTI BAT2 1473 TA01 Si9926DY *COILCRAFT 1812LS-105XKBC 1 U ULTC1473 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) TOP VIEW ORDER PART DCIN, BAT1, BAT2 Supply Voltage .............. 0.3 to 32V NUMBER IN1 1 16 GA1 + + SENSE , SENSE , V .................................. 0.3 to 32V IN2 2 15 SAB1 GA1, GB1, GA2, GB2 ................................... 0.3 to 42V DIODE 3 14 GB1 LTC1473CGN SAB1, SAB2 .................................................0.3 to 32V + TIMER 4 13 SENSE LTC1473IGN SW, V ...................................................... 0.3 to 42V + GG V 5 12 SENSE IN1, IN2, DIODE........................................0.3V to 7.5V V 6 11 GA2 GG GN PART MARKING Junction Temperature (Note 2)............................. 125 C SW 7 10 SAB2 Operating Temperature Range GND 8 9 GB2 1473 Commercial ............................................. 0 C to 70 C GN PACKAGE 16-LEAD NARROW PLASTIC SSOP 1473I Industrial ........................................... 40 C to 85 C T = 125 C, q = 150 C/ W JMAX JA Storage Temperature Range ................. 65 C to 150 C Consult factory for Military grade parts. Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25 C. A + Test circuit, V = 20V, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS + V Supply Operating Range 4.75 30 V + I Supply Current V = V = 5V, V = 0V, V = V = 20V l 100 200 m A S IN1 DIODE IN2 SENSE SENSE + V V Gate Supply Voltage V = V V l 7.5 8.5 9.5 V GS GS GS GG + + + V V Undervoltage Lockout Threshold V Ramping Down 2.7 3.1 3.5 V UVLO + + V V Undervoltage Lockout Hysteresis 0.75 1 1.25 V UVLOHYS V Digital Input Logic High l 2 1.6 V HIDIGIN V Digital Input Logic Low l 1.5 0.8 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 = 20V l 5.0 5.7 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 = 20V l 00.4 V GS(OFF) GA1 GA2 GB1 GB2 SAB1 SAB2 + + + I SENSE Input Bias Current V = V = 20V l 24.5 6.5 m A BSENSE SENSE SENSE + V = V = 0V (Note 3) l 300 160 100 m A SENSE SENSE + I SENSE Input Bias Current V = V = 20V l 24.5 6.5 m A BSENSE SENSE SENSE + V = V = 0V (Note 3) l 300 160 100 m A SENSE SENSE + V Inrush Current Limit Sense Voltage V = 20V (V V ) l 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 = 0.8V 5 20 35 m A PDSAB IN1 IN2 DIODE V = V = 0.8V, V = 2V 30 200 350 m A IN1 IN2 DIODE I Timer Source Current V = 0.8V, V = V = 2V, V = 0V, l 35.5 9 m A TIMER IN1 IN2 DIODE TIMER + V V = 300mV SENSE SENSE V Timer Latch Threshold Voltage V = 0.8V, V = V = 2V l 1.1 1.2 1.3 V TIMER IN1 IN2 DIODE t Gate Drive Rise Time C = 1000pF, V = V = 0V (Note 4) 33 m s ON GS SAB1 SAB2 t Gate Drive Fall Time C = 1000pF, V = V = 20V (Note 4) 2 m s OFF GS SAB1 SAB2 t Gate Drive Turn-On Delay C = 1000pF, V = V = 0V (Note 4) 22 m s D1 GS SAB1 SAB2 t Gate Drive Turn-Off Delay C = 1000pF, V = V = 20V (Note 4) 1 m s D2 GS SAB1 SAB2 f V Regulator Operating Frequency 30 kHz OVGG GG 2 U W U W U WW