1 www.semtech.com sc451 portable imvp-iv? and imvp-iv+? single phase power supply controller power management february 2, 2005 description features applications conceptual application circuit ? imvp-iv? and imvp-iv+? compliant single chip solution ? on chip clk_enable# and imvp4_pwrgd outputs ? backward compatible with sc1479 ? high speed hysteretic controller ? single phase operation ? selectable analog or vid controlled deepersleep setting ? 6 bit vid programmable output ? integrated drivers with soft high side turn-on ? programmable softstart ? programmable boot voltage ? programmable deepersleep voltage ? under-voltage lock out on vcca ? over-voltage protection on core ? current limit protection on core ? thermal protection ? powergood flag with blanking during vid or deepersleep mode changes ? automatic powersave at light load ? tssop-28, tssop-38 and mlp 6x6-28 package options the sc451 powerstep iv? ic is a single chip high-perfor- mance hysteretic pwm controller. with its integrated smartdriver?, it powers advanced imvp-iv? and imvp4+? processors. the sc451 features extended intel mobile volt- age positioning (imvp?) to increase battery life by reduc- ing the voltage at the processor when it is heavily loaded. it directly supports intel?s speedstep? processors for even longer battery life. the sc451 fully supports the intel? geyserville-iii core voltage specification. it provides direct ?deeper sleep? mode and boot voltage support. automatic ?power-save? is present to prevent negative current flow in the low-side fet during light loading conditions, saving even more power. the high side driver initially turns on with a weak drive to reduce ringing, emi, and capacitive turn-on of the low side. a 6-bit dac, accurate to 0.85%, sets the output voltage reference, and implements the 0.700v to 1.708v range required by the processor. the hysteretic converter uses a comparator without an error amplifier, and therefore pro- vides the fastest possible transient response, while avoid- ing the stability issues inherent to classical pwm control- lers. the dac is externally slew rate limited to minimize transient currents and audible noise. the sc451 operates from 5vdc and also features soft-start, an open-drain pwrgd signal with power-good blanking, and an enable input. programmable current limiting shuts down the sc451 after 32 current limit pulses. in addition, it comes in a space-saving mlp 6x6-28 and tssop-28 package. tssop-38 package is also available which pro- vides a pin to pin upgrade to a dual phase solution using semtech?s dual phase controller sc450. ? low power notebook and laptop computers ? embedded applications powerstep iv? is a trademark of semtech corporation. other trademarks or registered trademarks may be claimed as the property of others. sc451 single phase im vp-iv/im vp-iv+ power supply smart driver pwm controller vid logic and dac vid (5:0) vin v 5 v cca vcore 0.700v-1.708v .com .com .com 4 .com u datasheet
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