R1271x Series 30 V, 1 A Synchronous PWM Step-down DC/DC Converter for Automotive Applications No. EC-517-210514 OVERVIEW The R1271x is a synchronous step-down DC/DC converter with a maximum input voltage rating of 42V. This device is suitable for small inductors with the switching frequency of 2 MHz. The external components are only an inductor and several capacitors and a resistance. The tiny DFN package option makes the power circuit compact . KEY BENEFITS High efficiency 85% is realized with switching frequency of 2 MHz The output voltage is maintained at cranking by reducing a switching frequency to minimum 1/4 of normal frequency. EMI noise reduction by using a spread spectrum clock generator. (Diffusion Rate: +10%). TYPICAL APPLICATION KEY SPECIFICATIONS Input Voltage Range (Maximum Ratings): 3.6 V to 30 V (42 V) L LX VOUT Start-up Voltage: 4.5 V VIN Standby Current: Typ. 4 A C C IN BST VCC BST C VCC R1271x Operating Temperature Range: -40C to 125C LIMIT GND Output Voltage Accuracy: 1.0% (Ta = 25C) CSS VOUT R CE C Oscillator Frequency: Typ.2 MHz (Fixed inside the IC) OUT CE PGOOD CE Control Spread Spectrum Clock Generator (SSCG): Diffusion Rate: Typ. +10% Minimum On-Time: Typ. 70 ns Minimum Off-Time: Typ. 120 ns PCB EXAMPLE Duty-over: Oscillation Frequency x 1 ~ 1/4 Soft start function Thermal Shutdown: Typ. Tj = 160C Undervoltage Lockout (UVLO): VCC = 3.3 V (Typ.) Overvoltage Lockout (OVLO): VIN = 35 V (Typ.) Overvoltage Detection (OVD): Output Voltage (VOUT) +10% LX Current Limit: Typ. 1.8 A (LIMIT Pin Open) 9.1 High-side MOS FET On Resistance: Typ. 0.4 Low-side MOS FET On Resistance: Typ. 0.2 7.6 PACKAGES EV Board (DFN3030-12B) OPTIONAL FUNCTIONS Product Name Set Output Voltage (V ) SET R1271x331 3.3 V R1271x501 5.0 V Overcurrent Product Name SSCG Protection R1271xxx1A Hiccup-type Disable *Wettable Flanks HSOP-18 R1271xxx1B Latch-type Disable DFN3030-12B 5.2 x 6.2 x 1.45 (mm) R1271xxx1C Hiccup-type Enable 3.0 x 3.0 x 0.8 (mm) R1271xxx1D Latch-type Enable APPLICATIONS Power supply for accessories such as Power window, Electronic mirror and Around view monitor 1 R1271x No. EC-517-210514 SELECTION GUIDE The set Output Voltage, the Optional functions and Quality class can be designated by users request. Selection Guide Product Name Package Quantity per Reel Pb Free Halogen Free R1271Lxx1*-TR- DFN3030-12B 3,000 pcs Yes Yes R1271Sxx1*-E2- E HSOP-18 1,000 pcs Yes Yes xx Select the Set Output Voltage (VSET). xx Set Output Voltage (V ) SET 33 3.3 V 50 5.0 V Select the optional functions. Overcurrent Protection SSCG A Hiccup-type Disable B Latch-type Disable C Hiccup-type Enable D Latch-type Enable Select the quality class. Operating Temperature Range Test Temp. A 40C to 125C 25C, High K 40C to 125C Low, 25C, High 2