1 information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa - tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. pad function 1. 2. 3. 4. 5. 6. 7. 8. gnd vc shdn fb sync boost v in sw 80mils 138mils, backside metal: alloyed gold layer backside potential: gnd description the rh1959 is a 500khz monolithic buck mode switching regulator with an on-die 4.5a switch. it can accept inputs up to 16v in to generate outputs as low as 1.21v out . all necessary circuitry including oscillator, control logic, comparators, error amplifiers, and reference are included on die, keeping solution size minimal and saving external components. high switching frequency allows a consid - erable reduction in the size of external capacitors and inductor. the topology is current mode for fast transient response and good loop stability. a special high speed 8 1 6 5 4 3 2 7 7 7 7 8 8 8 die cross reference ltc finished part number order part number rh1959mk rh1959mk rh1959mildice rh1959mildwf* please refer to ltc standard product data sheet for other applicable product information. *dwf = dice in wafer form. 4.5a, 500khz step-down switching regulator bipolar process and new design techniques achieve high efficiency at high switching frequency. high efficiency is maintained over a wide output current range by keeping quiescent supply current to 4ma and by utilizing a boost capacitor to saturate the npn power switch. full cycle- by-cycle short-circuit protection and thermal shutdown are provided for safe operation in overload conditions. a shutdown signal reduces supply current to 20a while synchronization allows an external logic level signal to vary adjust switching frequency between 580khz and 1mhz. absolute maximum ratings input voltage ............................................................. 16v boost voltage ............................................................ 30v boost pin above input voltage .................................. 15v shdn pin voltage ....................................................... 7v (note 1) fb pin voltage .......................................................... 3.5v fb pin current .......................................................... 1ma sync pin voltage ........................................................ 7v dice/dwf specification rh1959mildice
2 wafer level testing is performed per the indicated specifications for dice. considerable differences in performance can often be observed for dice versus packaged units due to the influences of packaging and assembly on certain devices and/or parameters. please consult factory for more information on dice performance and lot qualifications via lot sampling test procedures. dice data sheet subject to change. please consult factory for current revision in production. i.d.no. 66-13-3415 dice/dwf electrical test limits for non-specified test conditions, t a = 25c, t j = 25c, v in = 5v, v c = 1.5v, boost = v in + 5v, switch open. (note 2) note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: dice are probe tested at 25c to the limits shown except for high current tests. dice are tested under low current conditions which assure full load current specifications when assembled in packaging systems approved by linear technology. note 3: gain is measured with a vc swing equal to 200mv above the switching threshold level to 200mv below the upper clamp level. note 4: minimum input voltage is not measured directly, but is guaranteed by other tests. it is defined as the voltage where internal bias lines are still regulated so that the reference voltage and oscillator frequency remain constant. actual minimum input voltage to maintain a regulated output will depend on output voltage and load current. note 5: this is the minimum voltage across the boost capacitor needed to guarantee full saturation of the internal power switch. note 6: boost current is the current flowing into the boost pin with the pin held 5v above input voltage. it flows only during switch on time. note 7: input supply current is the bias current drawn by the input pin with switching disabled. note 8: switch on resistance is calculated by dividing v in to v sw voltage by the forced current (4.5a). note 9: this parameter is not measured directly, but is guaranteed by design. linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2014 lt 0814 ? printed in usa parameter conditions min max units feedback voltage (adjustable) all conditions 1.19 1.23 v reference voltage line regulation 4.3v v in 15v C0.03 0.03 %/v feedback input bias current C0.5 0.5 a error amplifier voltage gain (note 3) 200 error amplifier transconductance (note 9) di (vc) = 10ma 1500 2700 mmho error amplifier source current v fb = 1.05v 140 320 ma error amplifier sink current v fb = 1.35v v fb = 1.35v 140 320 ma switch current limit (note 9) vc open, v fb = 1.05v, dc 50% 4.5 8.5 a switch on resistance (notes 8, 9) i sw = 4.5a 0.1 maximum switch duty cycle v fb = 1.05v v fb = 1.05v 90 % switch frequency vc set to give 50% duty cycle 460 540 khz switch frequency line regulation 4.3v v in 15v C0.15 0.15 %/v frequency shifting threshold on fb pin df = 10khz 0.5 1 v minimum input voltage (note 4) 4.3 v minimum boost voltage (notes 5, 9) i sw 4.5a 3 v boost current (notes 6, 9) i sw = 1a i sw = 4.5a 35 140 ma ma input supply current (note 7) 5.4 ma shutdown supply current v shdn = 0v, v sw = 0v, vc open 50 a lockout threshold vc open, v fb = 1.05v, dc 50% 2.3 2.46 v shutdown thresholds vc open device shutting down device starting up 0.13 0.25 0.6 0.7 v v synchronization threshold 2.2 v synchronizing range 580 1000 khz dice/dwf specification rh1959mildice
|
