Nisshinbo Micro Devices Inc. R1242S001A-E2-FE

The R1242S is a CMOS-based 30 V input, 3 A, synchronous rectified step-down DC/DC converter with builtin High-side switch. The R1242S contains Nch High-side Tr. (Typ. 0.1 Ω) and can supply maximum 3 A output current. In order to reduce heat generation caused by energy loss, FET can be used as Low-side switch. Lowside switch turns off when ICs shut down. The R1242S consists of the followings: an oscillator, a PWM control circuit, a voltage reference unit, an error amplifier, a phase compensation circuit, a slope control circuit, a softstart circuit, protection circuits, an internal regulator, a switch, and so on. Also, the R1242S consists of the following external components: an inductor, resistors, an external FET, and capacitors. The R1242S operates with current mode topology, which does not require any sense resistor. As a result, the R1242S can achieve high speed and high efficiency. The oscillator frequencies for each version are set as follows; adjustable between 330 kHz to 1000 kHz for versions A and B, 330 kHz for versions C and D, 500 kHz for versions E and F, and 1000 kHz for versions G and H. The R1242S is equipped with the protection functions, such as peak current limit function, latch function, fold back function, thermal-shutdown function, and undervoltage-lockout (UVLO) function. Peak current limit function restricts the maximum current into 4.5 A. Latch function (comes with versions A, C, E, and G) shuts off the output if current limit detection continues for a certain period of time. Fold back function (comes with versions B, D, F, and H) reduces the initial oscillator frequencies into 1/4 when output is short-circuited.

• Supply Current .. Typ. 0.8 mA (ΔV₁ₙ = 30ΔV, Set VFB = 1.0 Vₚ)
• Standby Current.. . Typ. 0 μA (V₁ₙ = 30 V, CE = L)
• Input Voltage Range . .. 5 V to 30 V
• Output Voltage Range ................. .. 0.8 V to 15 V, Adjustable using external resistors
• Feed Back Voltage Accuracy ......... .. 0.8 V with 1.5% accuracy
• Output Current .. ... 3 A*
• Oscillator Frequency ..... .. 330 kHz to 1 MHz (Ver. A/B), 330 kHz (Ver. C/D), 500 kHz, (Ver. E/F), 1000 kHz (Ver. G/H)
• Maximum Duty Cycle ... .. Typ. 88%
• UVLO Detector Threshold . .. Typ. 3.6 V
• Soft-start Time ...... ... Typ. 0.5 ms
• Peak Current Limit ... .. Typ. 4.5 A
• Thermal Shutdown...... . Typ. 160°C
• Latch Type Protection .... . Delay Time: Typ. 5 ms (Ver. A/C/E/G)
• Fold-back Type Protection . . Fold-back Frequency: Ver. B: fosc x 1/4, Ver. D: 83 kHz, Ver. F: 125 kHz, Ver. H: 250 kHz
• Package ..... . HSOP-8E

• Digital Home Appliances: Digital TVs, DVD Players
• Office Automation Equipment: Printers, Fax
• Hand-held Communication Equipment: Cameras, Video Recorders
• Battery-powered Equipment