MAX1966/MAX1967 19-2286 Rev 1 9/03 Low-Cost Voltage-Mode PWM Step-Down Controllers General Description Features The MAX1966/MAX1967 are voltage-mode pulse-width- Cost-Optimized Design modulated (PWM), step-down DC-DC controllers that No Schottky Diode or Current-Sense Resistor are ideal for a variety of cost-sensitive applications. Required They drive low-cost N-MOSFETs for both the high-side switch and synchronous rectifier and require no external >95% Efficiency Schottky power diode or current-sense resistor. Short- Low-Cost External Components circuit and current-limit protection is provided by sens- All N-Channel FET Design ing the drain-to-source voltage on the low-side FET. Both devices can supply outputs as low as 0.8V and are 2.7V to 5.5V Input Range (MAX1966) well suited for DSP cores and other low-voltage logic. 2.7V to 28V Input Range (MAX1967) The MAX1966 has an input range of 2.7V to 5.5V while 0.8V Feedback for Low-Voltage Outputs the MAX1967 has an input range of 2.7V to 28V. In ultra-low-cost designs, the MAX1966/MAX1967 can 100kHz Switching Frequency Accommodates provide efficiency exceeding 90% and can achieve Low-Cost Components 95% efficiency with optimized component selection. Thermal Shutdown The MAX1966/MAX1967 operate at 100kHz and ac- Output Current-Limit and Short-Circuit Protection commodate aluminum electrolytic capacitors and pow- dered-iron core magnetics in minimum-cost designs. They also provide excellent performance with high-per- formance surface-mount components. The MAX1966 is Ordering Information available in a low-cost 8-pin SO package. The MAX1967 is available in a 10-pin MAX package. PART TEMP RANGE PIN-PACKAGE Applications MAX1966ESA -40C to +85C 8 SO MAX1967EUB -40C to +85C 10 MAX Set-Top Boxes Telecom Power Supplies Graphic Card Supplies Networking Power Supplies xDSL Modems and Routers Termination Supplies Typical Operating Circuit Cable Modems and Routers 2.7V TO 5.5V INPUT Pin Configurations VIN BST DH TOP VIEW V OUT MAX1966 BST 1 8 DH LX COMP/EN 2 7 LX COMP/EN DL MAX1966 FB 3 6 GND VIN 4 5 DL FB GND SO Pin Configurations continued 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.Low-Cost Voltage-Mode PWM Step-Down Controllers ABSOLUTE MAXIMUM RATINGS (All Voltages Referenced to GND, Unless Otherwise Noted) VL Short to GND (MAX1967) ....................................................5s VIN to GND (MAX1966)............................................-0.3V to +6V RMS Input Current (any pin).............................................50mA VIN to GND (MAX1967)..........................................-0.3V to +30V Continuous Power Dissipation (T = +70C) A VCC to GND (MAX1967)..........-0.3V, lower of 6V or (V + 0.3V) 8-Pin SO (derate 5.88mW/C above +70C)................471mW IN FB to GND ................................................................-0.3V to +6V 10-Pin MAX (derate 5.6mW/C above +70C) ...........444mW DL, COMP/EN to GND (MAX1966) ................-0.3V to V + 0.3V Operating Temperature Range ...........................-40C to +85C IN VL, DL, COMP/EN to GND (MAX1967).........-0.3V to V + 0.3V Junction Temperature......................................................+150C CC BST to LX..................................................................-0.3V to +6V Storage Temperature Range .............................-65C to +150C DH to LX........................................................-0.3V to BST + 0.3V Lead Temperature (soldering, 10s) .................................+300C 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 (VIN = VL = VCC = 5V (MAX1967), VIN = 5V (MAX1966), T = -40C to +85C (Note 1), unless otherwise noted. Typical values are at A T = +25C.) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS MAX1967 VIN Operating Range 4.9 28 V MAX1967 Operating Range with 2.7 5.5 V VIN = VL MAX1966 VIN Operating Range 2.7 5.5 V MAX1967 VL Undervoltage Rising and falling edge, hysteresis = 2% 2.35 2.53 2.66 V Lockout (UVLO) Trip Level MAX1966 VIN UVLO Rising and falling edge, hysteresis = 2% 2.35 2.53 2.66 V Trip Level Operating Supply Current FB = 0.88V, no switching 0.7 3 mA 5.5V < VIN < 28V, 1mA < I < 25mA, VL V L Output Vol ta ge ( M AX1967 O nly) 4.67 5 5.3 V FB = 0.88V Thermal Shutdown (Note 1) Rising temperature, typical hysteresis = 10C 160 C OSCILLATOR 0C to +85C 82 102 124 Frequency f kHz OSC -40C to +85C 79 102 127 Minimum Duty Cycle 10 % Maximum Duty Cycle 90 95 % SOFT-START Internal 6-bit DAC for converter to ramp from 1024 / Digital Ramp Period s 0 to full output voltage f OSC V / OUT Soft-Start Levels V 64 ERROR AMPLIFIER 2.7V < VCC < 5.5V, 0C to +85C 0.787 0.800 0.815 FB Regulation Voltage V (MAX1967) 2.7V < VCC < 5.5V, -40C to +85C 0.782 0.800 0.815 2.7V < VIN < 5.5V, 0C to +85C 0.787 0.800 0.815 FB Regulation Voltage V (MAX1966) 2.7V < VIN < 5.5V, -40C to +85C 0.782 0.800 0.815 FB to COMP/EN Gain 4000 V/V 2 MAX1966/MAX1967