MAX8741/MAX8742 19-3262 Rev 1 8/05 500kHz Multi-Output Power-Supply Controllers with High Impedance in Shutdown General Description Features The MAX8741/MAX8742 are buck-topology, step-down, 97% Efficiency switch-mode, power-supply controllers that generate 4.2V to 30V Input Range logic-supply voltages in battery-powered systems. These 2.5V to 5.5V Dual Adjustable Outputs high-performance, dual/triple-output devices include on- Selectable 3.3V and 5V Fixed or Adjustable board power-up sequencing, power-good signaling with Outputs (Dual Mode) delay, digital soft-start, secondary winding control, low- 12V Linear Regulator dropout circuitry, internal frequency-compensation net- works, and automatic bootstrapping. Adjustable Secondary Feedback (MAX8741) 5V/50mA Linear-Regulator Output Up to 97% efficiency is achieved through synchronous Precision 2.5V Reference Output rectification and Maxims proprietary Idle Mode control scheme. Efficiency is greater than 80% over a 1000:1 Programmable Power-Up Sequencing load-current range, which extends battery life in system Power-Good (RESET) Output suspend or standby mode. Excellent dynamic response Output Overvoltage Protection corrects output load transients within five clock cycles. Output Undervoltage Shutdown Strong 1A on-board gate drivers ensure fast external 333kHz/500kHz Low-Noise, Fixed-Frequency n-channel MOSFET switching. Operation These devices feature a logic-controlled and synchroniz- Low-Dropout, 98% Duty-Factor Operation able, fixed-frequency, pulse-width-modulation (PWM) 2.5mW Typical Quiescent Power (12V Input, operating mode. This reduces noise and RF interference Both SMPSs On) in sensitive mobile communications and pen-entry appli- 4A Typical Shutdown Current cations. Asserting the SKIP pin enables fixed-frequency mode, for lowest noise under all load conditions. The MAX8741/MAX8742 include two PWM regulators, Ordering Information adjustable from 2.5V to 5.5V with fixed 5.0V and 3.3V PART TEMP RANGE PIN-PACKAGE modes. All these devices include secondary feedback regulation, and the MAX8742 contains a 12V/120mA lin- MAX8741EAI -40C to +85C 28 SSOP ear regulator. The MAX8741 includes a secondary feed- MAX8741EAI+ -40C to +85C 28 SSOP back input (SECFB), plus a control pin (STEER) that MAX8741ETJ -40C to +85C 32 Thin QFN 5m m x 5mm selects which PWM (3.3V or 5V) receives the secondary MAX8741ETJ+ -40C to +85C 32 Thin QFN 5m m x 5mm feedback signal. SECFB provides a method for adjusting the secondary winding voltage regulation point with an +Denotes lead-free package. external resistor-divider, and is intended to aid in creating Ordering Information continued at end of data sheet. auxiliary voltages other than fixed 12V. Functional Diagram The MAX8741/MAX8742 contain internal output overvolt- age- and undervoltage-protection features. INPUT Applications 5V (RTC) 12V Notebook and Subnotebook Computers 5V 12V LINEAR LINEAR PDAs and Mobile Communicators Desktop CPU Local DC-DC Converters 3.3V 3.3V 5V 5V SMPS SMPS Idle Mode is a trademark of Maxim Integrated Products, Inc. POWER-UP POWER- Dual Mode is a trademark of Maxim Integrated Products, Inc. ON/OFF RESET SEQUENCE GOOD Pin Configurations appear at end of data sheet. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.500kHz Multi-Output Power-Supply Controllers with High Impedance in Shutdown ABSOLUTE MAXIMUM RATINGS V+ to GND..............................................................-0.3V to +36V DH3 to LX3 ..............................................-0.3V to (BST3 + 0.3V) PGND to GND.....................................................................0.3V DH5 to LX5 ..............................................-0.3V to (BST5 + 0.3V) V to GND ................................................................-0.3V to +6V V , REF Short to GND ................................................Momentary L L BST3, BST5 to GND ..............................................-0.3V to +36V 12OUT Short to GND..................................................Continuous CSH3, CSH5 to GND................................................-0.3V to +6V REF Current...........................................................+5mA to -1mA FB3 to GND..............................................-0.3V to (CSL3 + 0.3V) V Current.........................................................................+50mA L FB5 to GND...............................................-0.3V to (CSL5 +0.3V) 12OUT Current ............................................................+200mA LX3 to BST3..............................................................-6V to +0.3V V Shunt Current............................................................+15mA DD LX5 to BST5..............................................................-6V to +0.3V Continuous Power Dissipation (T = +70C) A REF, SYNC, SEQ, STEER, SKIP, 28-Pin SSOP (derate 9.52mW/C above +70C) ........762mW TIME/ON5, SECFB, RESET to GND ..........-0.3V to (V + 0.3V) 32-Pin Thin QFN (derate 21.3mW/C above +70C) ....1702mW L V to GND............................................................-0.3V to +20V Operating Temperature Range ...........................-40C to +85C DD RUN/ON3, SHDN to GND.............................-0.3V to (V+ + 0.3V) Storage Temperature Range ............................-65C to +160C 12OUT to GND ..........................................-0.3V to (V + 0.3V) Lead Temperature (soldering, 10s) ................................+300C DD DL3, DL5 to PGND........................................-0.3V to (V + 0.3V) L Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V+ = 15V, both PWMs on, SYNC = V , V load = 0, REF load = 0, SKIP = 0, T = 0C to +85C, unless otherwise noted. Typical L L A values are at T = +25C.) A PARAMETER CONDITIONS MIN TYP MAX UNITS MAIN SMPS CONTROLLERS Input Voltage Range 4.2 30.0 V V+ = 4.2V to 30V, CSH3 - CSL3 = 0, 3V Output Voltage in Adjustable Mode 2.42 2.5 2.58 V CSL3 connected to FB3 V+ = 4.2V to 30V, 0 < CSH3 - CSL3 3V Output Voltage in Fixed Mode 3.20 3.39 3.47 V < 80mV, FB3 = 0 V+ = 4.2V to 30V, CSH5 - CSL5 = 0, 5V Output Voltage in Adjustable Mode 2.42 2.5 2.58 V CSL5 connected to FB5 V+ = 5.3V to 30V, 0 < CSH5 - CSL5 5V Output Voltage in Fixed Mode 4.85 5.13 5.25 V < 80mV, FB5 = 0 Output Voltage Adjust Range Either SMPS REF 5.5 V Adjustable-Mode Threshold Voltage Dual-mode comparator 0.5 1.1 V Load Regulation Either SMPS, 0 < CSH - CSL < 80mV -2 % Line Regulation Either SMPS, 5.2V < V+ < 30V 0.03 %/V CSH3 - CSL3 or CSH5 - CSL5 80 100 120 Current-Limit Threshold mV SKIP = V or V < 13V or SECFB < 2.44V -50 -100 -150 L DD Idle-Mode Threshold SKIP = 0, not tested 10 25 40 mV From enable to 95% full current limit with Soft-Start Ramp Time 512 Clks respect to f (Note 1) OSC SYNC = V 450 500 550 L Oscillator Frequency kHz SYNC = 0 283 333 383 2 MAX8741/MAX8742