R1272S-Y Series 34 V Input Synchronous Step-down DC / DC Controller for Industrial Applications NO.EA-385-200605 OUTLINE The R1272S is a step-down DC/DC controller which can generate an output voltage of 0.7 V to 5.3 V by driving external high- / low-side NMOSs. By the adoption of a unique current mode PWM architecture without an external current sense resistor, the R1272S can make up a stable DC/DC converter with high-efficiency even if adding low Ron MOSFETs and a low DCR inductor externally. And, by the frequency characteristics optimization with using external phase compensation capacitor, the R1272S can achieve a high-speed response to variations of input voltage and load current. The user-settable oscillation frequency is adjustable (1) over a range of 250 kHz to 1 MHz by external resistors, and also can be synchronized to an external clock. Output Voltage Control Methods have three operating modes: Forced PWM mode, PLL PWM mode, and PWM/VFM Auto-switching mode. These modes are selectable according to conditions of the MODE pin. Especially, the PWM/VFM Auto-switching mode can improve efficiency under light load conditions. The R1272S can minimize the output voltage drop caused by an input voltage drop at cranking, with reducing the operating frequency (the lowest possible limit is a quarter of the frequency) so that the off-duty is reduced. Protection functions include a current limit function, an UVLO (Under Voltage Lock Out) function, an OVP (Over Voltage Protection) function, a soft-start function, a low-inductor current shutdown function, and so on. Also, a power good function provides the status of output with using a power good (PGOOD) pin. For EMI reduction, SSCG (Spread-Spectrum Clock Generator) for diffused oscillation frequency at the PWM operation is optionally available. The R1272S is available in HSOP-18 package. This is a high-reliability semiconductor device for industrial application (-Y) that has passed both the screening at high temperature and the reliability test with extended hours. FEATURES Operating Voltage (Maximum Rating) 4.0 V to 34 V (36 V) Operating Temperature Range -40C Ta 105C Start-up Voltage 4.5 V Output Voltage 0.7 V to 5.3 V Feedback Voltage Tolerance 0.64 V 1% Consumption Current at No Load (at VFM mode) Typ.15 A (1) Adjustable Oscillation Frequency 250 kHz to 1 MHz (1) Synchronizable Clock Frequency 250 kHz to 1 MHz Spreading Rate for SSCG Typ. 3.6% Minimum On-Time Typ.100 ns Minimum Off-Time Typ.120 ns (at regulation mode) At dropout, actual minimum off-time is reduced. (2) Adjustable Soft-start Time Typ.500 s Pre-bias Start-up Anti-phase Clock Output Thermal Shutdown Function Tj = 160C (Typ.) (1) The adjustable oscillation frequency range becomes 250 kHz fOSC 600 kHz when 0.7 V VOUT < 1.35V. (2) 500 s(Typ.) as a lower limit with using an external capacitor. Otherwise, available the tracking function through the application of an external voltage. 1 R1272S-Y NO.EA-385-200605 Under Voltage Lockout (UVLO) Function Typ. 3.3 V Over Voltage Detection (OVD) Function FB pin voltage (V ) + 10% (Typ.) FB Detection/Release Hysteresis FB pin voltage (VFB) x 3% (Typ.) Under Voltage Detection (UVD) Function FB pin voltage (V ) - 10% (Typ.) FB Detection/Release Hysteresis FB pin voltage (VFB) x 3% (Typ.) Over-current Protection Hiccup-mode / Latch mode Selectable Current Limit Threshold 50 mV / 70 mV / 100 mV Power Good Output NMOS Open-drain Output Package HSOP-18 APPLICATIONS Industrial equipments such as FA and smart meters. Equipments used under high-temperature conditions such as surveillance camera and vending machine. Equipments accompanied by self-heating such as motor and lighting. SELECTION GUIDE The function and setting for the ICs are selectable at the users request. Product Name Package Quantity per Reel Pb Free Halogen Free R1272SxxyA-E2-YE HSOP-18 1,000 Yes Yes xx : Select the combination of processing and function. xx Over Current Protection SSCG Output Voltage Range 00 Non-latch type hiccup mode Disable 3.15 V < VOUT 5.3 V 01 Latch mode Disable 3.15 V < VOUT 5.3 V 03 Latch mode Enable 3.15 V < V 5.3 V OUT 10 Non-latch type hiccup mode Disable 0.7 V V 3.15 V OUT 11 Latch mode Disable 0.7 V V 3.15 V OUT 13 Latch mode Enable 0.7 V V 3.15 V OUT If required a version with SSCG function, please contact our sales offices. y : Select the current limit threshold voltage. Set Voltage for Current y Limit Threshold (Typ.) 1 50 mV 2 70 mV 3 100 mV 2