20 Years of Xmore® +++ 3.5" All-Rounder TFT Display +++ Monitoring and Remote with Ultra-Low Power 0.25µA IO-Link Wireless Module

Ideal for Large Loads up to 1 A:
Synchronous DC/DC Step-Down Switching Regulator from ABLIC

The S-19915A/B from ABLIC is a DC/DC step-down converter that has been specially developed for harsh environments in the automotive and industrial sectors.

With an input voltage range of 4 V to 36 V and a peak of up to 45 V, it can be used in a wide range of applications. The converter offers high reliability and efficiency while saving cost and space in the switching regulator design.

The spread spectrum clock generation in the S-19915A/B reduces conducted interference by around 33 %. This minimizes EMC measures in the circuit design and thus saves costs and space on the circuit board.

Input voltage range and load dump resistance

The input voltage range of 4 V to 36 V covers the most important voltage levels in industry and automotive from 24 V to 15 V and 12 V. The step-down converter is AEC-Q100 qualified, provides a load current of up to 1 A and can withstand a load dump of up to 45 V. The operating temperature may range from - 40 °C to 125 °C. It has an enable pin and soft-start functionality with a fixed time constant tSS = 5.8 ms (typ.).

Improved EM compatibility

The spread spectrum clock generation used in the S-19915A/B reduces the conducted interference of the regulator clocked at 2.2 MHz by approx. 33 % (1/3). Necessary EMC measures in the circuit design are eliminated or reduced to a minimum.

Performance / Efficiency h / 100 % - Duty - Cycle

An important aspect of energy utilization is the efficiency h at the lowest load currents. A look at the so-called performance curve (Fig. 4:) shows that the S-19955A/B series, thanks to pulse-frequency modulation, already achieves efficiencies of ³ 70 % at the lowest load currents (in the one to two-digit mA range).

Thanks to the 100 % duty cycle capability, the controller can control the H-side MOSFET completely. This is particularly helpful in applications where the difference between input and output voltage is very small.

Space requirements - Layout

The well thought-out pin assignment, the switching frequency of fSW = 2.2 MHz and the synchronous topology ensure an uncomplicated and quick PCB layout in the smallest of spaces. The aforementioned spread spectrum technology contributes to improved EM compatibility and component savings in direct comparison with conventional regulators.

The internal low-ripple circuit also helps to minimize costs and installation space, as this performance feature means that capacitors with a smaller capacitance and size can be used for the same ripple. The figure shows that with an output ripple < 10 mV, the capacitance can be reduced by half compared to a conventional switching regulator without a low-ripple circuit.

Depending on the mission profile, the S-19915A/B series can be used to implement extremely small solutions in the smallest of spaces.

ABLIC recommends the AECQ-200 qualified thin-film power inductors from TDK's TFM322512 series in the BOM. The maximum height with a dielectric strength of up to 40 V is just 1.2 mm.

ABLIC offers the S-19915 in two variants that differ in their short-circuit behavior: S-19915A (hiccup control) and S-19915B (latch control).
Both variants are available in the space-saving HTMSOP-8 package or HSNT-8 package (2030). Both housings have an E-pad for better connection and cooling via the PCB.

Technical data:

• Input voltage from 4.5 V to 36 V
• Load dump strength (load dump) 45 V
• Temperature range from - 40 °C to 125 °C AEC-Q100 qualified
• Output current up to 1 A
• Output voltage - adjustable from 2.5 V to 12 V
• Switching frequency fSW = 2.2 MHz (typ.)
• Spread spectrum improves EMC
• 100 % duty cycle operation
• Efficiency ɳ à 60 % @ IL =2 mA to 91 % @ IL = 600 mA
• Enable pin
• Soft start tSS = 5.8 ms (typ.)
• Internal compensation
• PFM @ light Load
• Compact housing with E-pad for better heat dissipation
  • HTMSOP-8 package
  • HSNT-8 package (2030)
• Low wiring effort
• Protection circuits against:
  Undervoltage (UVLO) 3.35 V (typ.)
  Overtemperature OT - TSD @ typ. 170 °C, release 150 °C THYS= 20 K
  Short circuit ISHORT:
  • S-19915A - Hiccup-Ctrl
  • S-19915B - Latch-Ctrl

GLYN Board SUPPORT for a Quick Start

Request a free demo board now and start developing immediately.

For the output voltages VOUT = 3.3 V, 5 V and 12 V, we are happy to provide you with our demo board for reference designs.