BEL Power Solutions - Point-of-Load Converters are recommended for regulated bus converters in Intermediate Bus Architecture (IBA). YS12S10 Product Specifications, Documentation and Sourcing Information" target="_blank">The YS12S10 non-isolated DC-DC converter provides up to 10 A of output current in an industry standard surface mount package. The YS12S10 converter operates at 9.6 to 14 V DC input operation and is ideal for intermediate bus architectures that typically require point-of-load (POL) power. The converters provide extremely tight regulation, programmable output voltages from 0.7525 to 5.5 VDC.
The YS12S10 converter provides excellent thermal performance even in high temperature convection. This performance is achieved through the use of advanced circuitry, packaging and processing techniques to enable designs with ultra-high efficiency, excellent thermal management and a very low body profile.
The lower body profile and isolation of the heat sinks minimize resistance to system airflow, enhancing cooling for upstream and downstream equipment. The use of 100% automated assembly, coupled with advanced power electronics and thermal design, makes the product extremely reliable.
Intermediate bus structure Telecom data communication distributed power architecture? Servers, workstations Efficient - no heatsinks required Reduce total solution board area Tape and reel packaging Compatible with pick and place equipment Minimize part numbers in inventory Low cost

Input and output impedance
The YS12S10 converter should be connected to the DC power supply with low impedance. In many applications, the inductance associated with the distribution from the power supply to the input of the converter can affect the stability of the converter. It is recommended to use a decoupling capacitor as close as possible to the converter input (minimum 47µF) to ensure converter stability and reduce input ripple voltage. Internally, the converter has an input capacitance of 20µf (low esr ceramic).
In typical applications, low ESR tantalum or POS capacitors are sufficient to provide adequate ripple voltage filtering at the converter input. However, very low esr ceramic capacitors are recommended to use 47 to 100µF at the input of the converter in order to minimize the input ripple voltage. They should be as close as possible to the input pins of the converter.
The YS12S10 is designed for stable operation with or without external capacitors. It is recommended to place low esr ceramic capacitors (minimum 47µf) as close as possible to the load for better transient performance and lower output voltage ripple.
In order to connect the load to the output pins of the converter, it is important to maintain low resistance and low inductance PCB traces. This is necessary to maintain good load regulation as the converter has no sense pins to compensate for the voltage drop associated with the power distribution system on the PCB.
On/Off (pin 1)

The ON/OFF pin (Pin 1) is used to remotely turn the power converter on or off via a system signal. There are two remote options available, positive logic (standard option) and negative logic, both referenced to GND (pin 5). A typical connection is shown in Figure A. The positive logic version turns on the converter when the ON/OFF pin is at logic high or left open, and turns it off when logic low or shorted to GND.
The negative logic version turns on the converter when the ON/OFF pin is at logic low or left open and turns off the converter when the ON/OFF pin is at logic high or connected to VIN.

The on/off pin is internally pulled up to the VIN for the forward logic version, and pulled down to the VIN for the reverse logic version. TTL or CMOS logic gates, open collector (open drain) transistors can be used to drive the on/off pins. When using an open-collector (open-drain) transistor with the negative logic option, add a 75 kΩ pull-up resistor (R*) on the VIN as shown in Figure A.
This device must be able to: drop to 0.2 mA at a low level voltage of 0.8 V - rise to 0.25 mA at a high logic level from 2.3 to 5 V When connected to a vehicle identification number (vin), a signal source up to 0.75mA.
Remote control (pin 2)

The converter's remote sensing function compensates for the voltage drop that occurs only between the converter's output pin (pin 4) and the load. The sense (pin 2) pin should be connected at the load or where it needs to be adjusted. There is no inductive function on the output ground return pin, where a solid ground plane should provide a low voltage drop.

If remote sensing is not required, the remote sensing pin must be connected to the VOUT pin (pin 4) to ensure that the converter will regulate at the specified output voltage. Without these connections, the converter will provide a slightly higher output voltage than specified.
Since the sense wires carry minimal current, there is no need to leave large traces on the end user board. However, the sense trace should be close to the ground plane to minimize system noise and ensure optimal performance. When using the remote sensing feature, care must be taken not to exceed the maximum allowable output power capability of the converter, which is equal to the product of the rated output voltage and the allowable output current for the given conditions.
When using remote sensing, the output voltage of the converter can be increased to 0.5 V above nominal to maintain the desired voltage across the load. Therefore, if necessary, the designer must reduce the maximum current (originally obtained from the derating curve) by the same percentage to ensure that the actual output power of the converter remains at or below the maximum allowable output power.
Output Voltage Programming (Pin 3)
The output voltage can be varied from 0.7525 to 5.5 V by connecting an external resistor between the trim pin (pin 3) and the ground pin (pin 5); see Figure C. Note that when the trimmer resistor is not connected, the output voltage of the converter is 0.7525 V.
The trim resistor RTRIM for the desired output voltage can be calculated using the following formula:

Output voltage programming configuration.
Note that the tolerance of the trimmer resistor directly affects the output voltage tolerance. Standard 1% or 0.5% resistors are recommended; for tighter tolerances, two parallel resistors are recommended instead of one of the standard values in Table 1.
The ground pin of the trimmer resistor should be connected directly to the ground pin of the converter with no voltage drop between the two. Table 1 provides trimmer resistor values for common output voltages.

Input Undervoltage Lockout Input undervoltage lockout is standard on this converter. When the input voltage drops below a predetermined voltage, the converter will shut down; when the vehicle identification number (vin) returns to the specified range, the converter will automatically start.
The input voltage must typically be 9.0 V for the converter to turn on. Once the converter is turned on, it turns off when the input voltage drops below 8.5 volts.
Output Over Current Protection (OCP)
The converter has overcurrent and short circuit protection. When an overcurrent condition is sensed, the converter will enter hiccup mode. Once the overload or short-circuit condition is removed, VOUT will return to its nominal value.
Over Temperature Protection (OTP)
The converter will shut down in overtemperature conditions to protect itself from overheating caused by operation outside the thermal derating curve or abnormal conditions such as system fan failure. After the drive has cooled to a safe operating temperature, it will restart automatically.
Safety Requirements According to UL60950 and EN60950, the converter complies with North American and international safety regulations. Under all operating conditions, the maximum DC voltage between any two pins is VIN. Therefore, the device has an ELV (Extra Low Voltage) output, meeting SELV requirements with all input voltages being ELV. The converter has no internal fuse. To comply with safety agency requirements, a recognized fuse with a maximum current rating of 15 amps must be used in series with the input line.
GENERAL INFORMATION The converter features a number of operational features, including thermal derating for vertical and horizontal mounting (maximum load current is a function of ambient temperature and airflow), efficiency, start-up and shutdown parameters, output ripple and noise, response to load step transient response to sudden changes, overloads and short circuits. The numbers are numbered as shown in figure XY, where X represents different output voltages and Y represents a specific figure (Y=1 for vertical thermal derating, …). For example, Figure x.1 typically refers to vertical thermal derating of all output voltages.
The following pages contain specific plots or waveforms related to the converter. The following are additional comments on specific data.
All data provided for the test conditions was performed with converters soldered on a test board, specifically a 0.060" thick four-layer printed wiring board (PWB). The top and bottom layers were not metallized. The two inner layers consisted of two copper, Used to provide traces to connect to the converter.
The absence of metallization of the outer layers and limited thermal connections ensure that heat transfer from the converter to the PWB is minimized. This provides a worst-case but consistent situation for thermal derating purposes.
All measurements requiring airflow were performed in vertical and horizontal wind tunnels using infrared thermal imaging and thermocouples.
Ensuring that components on the converter do not exceed their ratings is important to maintain high reliability. If the converter is expected to be operated at or near the maximum load specified in the derating curve, the actual operating temperature in the application should be carefully checked. Thermal imaging is best; if this capability is not available, a thermocouple can be used. AWG 40 gauge thermocouples are recommended to ensure measurement accuracy. Careful placement of thermocouple leads will further reduce measurement errors. The optimum measurement thermocouple position is shown in Figure D

The thermal decay effect load current versus ambient temperature and airflow velocity is shown in the figure. X.1 to X.2 at a maximum temperature of 110°C. Ambient temperature varies from 25°C to 85°C, airflow velocities from 30 to 500 lfm (0.15 m/s to 2.5 m/s), vertical and horizontal converter installations. The airflow during the test was parallel to the long axis of the converter, from pins 1 and 6 to pins 2–5.
For each set of conditions, the maximum load current is defined as the lowest of the following:
(i) the output current of any mosfet temperature not exceeding the maximum specified temperature (110°C) shown in the thermal image, or (ii) the maximum rated current of the converter (10A)
During normal operation, the maximum FET temperature less than or equal to 110°C should not be exceeded. To operate within the derating curve, the temperature on the PCB at the thermocouple location shown in Figure d should not exceed 110°C.
Efficiency graph X.3 shows the efficiency vs. load current graph at 25°C ambient temperature, 200 lfm (1 m/s) airflow velocity, and input voltages of 9.6 V, 12 V, and 14 V.
Power dissipation graph X.4 shows the power dissipation versus load current graph at Ta = 25°C, airflow velocity of 200 LFM (1 m/s), vertical mounting and input voltages of 9.6 V, 12 V and 14 V.
Ripple and Noise The output voltage ripple waveform is measured at full rated load current. Note that all output voltage waveforms are measured with 1µF ceramic capacitors.
The output voltage ripple and input reflected ripple current waveforms were obtained with the test setup shown in Figure E.

0V, 1: Available load current for VOUT=5.0 V converter versus ambient temperature and airflow rate, vertical mounting VIN=12 V, maximum MOSFET temperature 110°C.

Ambient temperature [degrees Celsius]

0V, 2: Usable load current for VOUT=5.0 V converter versus ambient temperature and airflow rate, horizontal installation, VIN=12 V, maximum MOSFET temperature does not exceed 110°C.

0V, 3: Efficiency vs. Load Current and Input Voltage
Vout = 5.0 V converter, mounted vertically, air velocity 200 lfm (1 m/s), Ta = 25°C.

0V, 4: Power loss vs. load current and input voltage
Vout = 5.0 V converter, mounted vertically, air velocity 200 lfm (1 m/s), Ta = 25°C.

0V, 5: Apply vin at full rated load current (resistor) and 100 F external capacitor (vin=12 V), turn on transient at vout=5.0 V. Top trace: vin (10µ
v/div.); trace: output voltage (1v/div.); time scale: 2ms/div.

5.0V, 6: Output voltage ripple at full rated load current (20 mV/div.), input resistive load, external capacitor is 100 F ceramic + 1 F ceramic, output voltage is 12 V=μμ
5.0V. Time scale: 2s/div.μ