Input and output impedance
The Y-series 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 converter input can affect converter stability. Decoupling capacitors are recommended 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 of 47-100µF are recommended at the input of the converter to minimize input ripple voltage. They should be as close as possible to the input pins of the converter.
The YNM05S05 is designed for stable operation with or without external capacitors. It is recommended to place low ESR ceramic capacitors (47µF minimum) as close to the load as possible to improve transient performance and reduce 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.
Input voltage ripple for various output voltages using four 47µF input ceramic capacitors. Shown is a 470µF polymer capacitor (6tp470m from Sanyo) in parallel with two 47µF ceramic capacitors at full load.

, on/off (pin 1)
The on/off pin (pin 1) is used to remotely turn the converter on or off with a system signal referenced to ground (pin 4).
To turn on the converter, the on/off pin should be at logic low or left open, to turn off the converter, the on/off pin should be at logic high or connected to the VIN.
The open/close pin is pulled down internally. 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, add a 5K pull-up resistor (R*) to the VIN as shown in Figure C. If the minimum input voltage is greater than 3.0 V, the external pull-up resistor can be increased to 10 K; if the minimum voltage is greater than 4.5 V, the external pull-up resistor can be increased to 20 K. The device must be able to:
– Drops down to 1.2 mA at low level voltages of 0.8 V – Gets up to 0.25 mA at high logic levels of 2.3 V – 5.5 V.
Output Voltage Programming (Pin 3)
The output voltage can be programmed from 0.7525 V to 3.63 V by connecting an external resistor between the trim pin (Pin 3) and the ground pin (Pin 4); note that when the trim resistor is not connected, the conversion The output voltage of the device is 0.7525 V.

Output voltage programming configuration.
The trim resistor RTRIM for the desired output voltage can be calculated using the following formula:
RTRIM Version 5.11 [Thousand]
(VO-REQ-0.7525)
where,
RTRIM Corporation  Trimming resistor required value [k]
Warwick  Desired (trimmed) output voltage [V]
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 2.3 V for the converter to turn on. Once the converter is turned on, it turns off when the input voltage drops below 2.2V.
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.
Overheating Protection (OTP)
The frequency converter will shut down in an overtemperature condition to protect itself from overheating caused by operation outside the thermal derating curve or under abnormal conditions such as system fan failure. After the torque converter 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 any operating conditions, the maximum DC voltage between the two pins is VIN. Therefore, the device has an extra-low voltage (ELV) output that meets SELV requirements with all input voltages at ELV. The converter has no internal fuse. To comply with safety agency requirements, a fuse rated at 15 amps must be used in series with the input line.
General Information The converter features a number of operational aspects including thermal derating (maximum load current as a function of ambient temperature and airflow) for vertical and horizontal installations, efficiency, startup and shutdown parameters, output ripple and noise, load Transient response to step changes, overloads and short circuits. Plots are numbered as shown in figure xy, where x represents different output voltages and y is related to a specific curve (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.
Test Conditions All data was obtained with the converter soldered to 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 consist of two oz. Copper composition used to provide traces to connect to the converter.
The lack of outer metallization and limited thermal connections ensure that heat transfer from the converter to the PWB is minimized. This provides a worst-case but consistent case 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 operate at or near the maximum load specified on the transition curve, it is prudent to check the actual operating temperature in the application. Thermal imaging is best; if this capability is not available, a thermocouple can be used. AWG#40 specification thermocouple is recommended to ensure measurement accuracy. Careful placement of thermocouple leads will further reduce measurement errors. For optimal measurement thermocouple positions

The thermal decay effect load current versus ambient temperature and airflow velocity is shown in the figure. The maximum temperature is 120 °C. Ambient temperatures vary between 25°C and 85°C, airflow rates from 30 to 500 LFM (0.15 m/s to 2.5 m/s), and vertical and horizontal converter installations.
For each set of conditions, the maximum load current is defined as:
(i) any MOSFET temperature not exceeding the output current of 120°C, the maximum specified temperature shown in the thermal image, or (ii) the converter's maximum current rating (5 A).
During normal operation, the derating curve for a maximum FET temperature less than or equal to 120°C should not be exceeded. To operate within the derating curve, the PCB temperature at the thermocouple location shown in Figure E must not exceed 120°C.
efficiency
Efficiency vs. load current plots at 25°C ambient temperature, 200 LFM (1m/s) airflow, and 4.5 V, 5.0 V, and 5.5 V input voltages.
Efficiency vs. load current plot 2.5 volts at 25°C ambient temperature, 200 LFM (1m/s) airflow velocity, and 3.0 V, 3.3 V, and 3.6 V output voltages.
Power consumption
The power consumption and load current diagram at Ta=25°C, the airflow velocity is 200 LFM (1m/s) when installed vertically, and the input voltages at 3.3V output are 4.5v, 5.0v and 5.5v. 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.