SC2608BSTRT

Simple, Synchronous Voltage Mode PWM Controller POWER MANAGEMENT Draft Description The SC2608B is a versatile voltage-mode PWM controller designed for use in step down DC/DC power supply applications. A simple, fixed frequency, highly efficient buck regulator can be implemented using the SC2608B with minimal external components. The input voltage range is from +5V to +12V. Internal level shift and drive circuitry eliminates the need for an expensive P-channel, high-side MOSFET. The small device footprint allows for compact circuit design. SC2608B features include temperature compensated voltage reference, triangle wave oscillator, current limit comparator, and an externally compensated error amplifier. Current limit is implemented by sensing the voltage drop across the bottom MOSFET RDS(ON). The SC2608B operates at a fixed frequency of 250kHz providing an optimum compromise between efficiency , external component size, and cost. SC2608B has a thermal protection circuit, which is activated if the junction temperature exceeds 150 OC. SC2608B Features +5V or +12V input voltage 250kHz operation High efficiency (>90%) 1.25% Voltage feedback accuracy over temperature Hiccup mode over current protection 1.2A output drive RDS(ON) Current sensing for protection Industrial temperature range Available in SO-8 package Integrated boot strap diode Thermal Shut down Fully WEEE and RoHS Compliant Applications Termination supplies Low cost microprocessor supplies Peripheral card supplies Industrial power supplies High density DC/DC conversion Typical Application Circuit Figure 1 Revision 4: Jan. 2007 1 www.semtech.com SC2608B POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. P ar am et er VCC to GN D BST to PHASE BST to GN D PHASE to GN D (note1) DH to PHASE (note1) S y m b ol M ax i m u m +20 +15 +20 -1 to +24 +15 -1 to +15 +7 +7 Units V V V V V V V V O DL to GN D (note2) COMP/SS to GN D SEN SE to GN D Thermal Resistance Junction to Case (SO-8) Thermal Resistance Junction to Ambient (SO-8) Operating Temperature Range Storage Temperature Range ESD Rating (Human Body Model) θJC θJA TJ TSTG ESD 40 120 -40 to +125 -65 to +150 4 C/W C/W O O C C O kV Note 1: Under pulsing condition, the peak negative voltage can not be lower than -3.6V with less than 20nS from 50% to 50%. Note 2: Under pulsing condition, the peak negative voltage can not be lower than -5V with less than 20nS from 50% to 50%. Electrical Characteristics Unless specified: VCC = 12V, VBST - VPhase = 12 V, VOUT = 3.3V, TJ = TA = 25oC. P ar am et er P ow er S u p p l y Sup p ly Voltage Sup p ly Current U n d er v ol t ag e L ock ou t UVLO Threshold Hysteresis E rror A m p l i f i er Feedback Voltage S y m b ol Con d i t i on s Min Ty p M ax Units VCC ICC VCOMP < 0.4V 4 6 14 6.5 V mA V th V hys 0< TJ < 85OC 3.75 80 3.85 V mV V FB 4.5V