application

Intermediate Bus Architecture Telecom Datacom Distributed Power Architecture Server, Workstation Benefits Efficient – No heat sinks Reduced overall solution board area Tape and reel packaging Compatible with pick and place equipment Minimized part numbers in inventory

Features Lead-Free/RoHS Compliant Design "G" option specifies RoHS for all six substances; Standard configuration complies with RoHS for lead solder exemption 1 Delivers up to 5 A No derating up to 85°C Surface mount package Industry standard package and pinout small footprint and low profile: 0.80" x 0.45" x 0.247 " (20.32 mm x 11.43 mm x 6.27 mm) Weight: 0.08 oz [2.22 g] Coplanarity is less than 0.003", maximum synchronous buck converter topology starts up to Pre-biased output requires no minimum load Programmable output voltage via external resistor Operating ambient temperature: -40°C to 85°C Remote on/off Fixed frequency operation Auto reset output Approx. 69 million hours, calculated according to Telcordia TR-332, Method 1 Case 1 for all materials to meet UL94, V-0 flammability rating

Description: The Y-Series non-isolated DC-DC converters provide up to 5 A of output current in an industry standard SurfaceMont package. Operating at 3.0–5.5 V input voltage, the ynm05s05 converter is ideal for intermediate bus structures where point-of-load (POL) power supply is often a requirement. The converter provides a tightly regulated programmable output voltage from 0.7525 V to 3.63 V. Y-Series converters provide excellent thermal performance even in high temperature environments with minimal airflow. No derating required below 85°C, even without airflow under natural convection conditions. This performance is achieved through the use of advanced circuitry, packaging and processing techniques, and is designed for ultra-high efficiency, superior thermal management and an extremely low body profile. The low body profile and exclusion of heat sinks minimize system airflow resistance, enhancing cooling of upstream and downstream equipment. The use of 100 % automated assembly, coupled with advanced power electronics and thermal design, gives the product an extremely high level of reliability.

Operating Input and Output Impedance Y-Series converters should be connected to a DC power source through 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. 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 input of the converter. However, to minimize input ripple voltage, it is recommended to use very low ESR ceramic capacitors of 47-100 µF at the input of the converter. They should be as close as possible to the input of the converter. The YNM05S05 is designed for stable operation with or without external capacitors. To improve transient performance and reduce output voltage ripple, it is recommended to place low ESR ceramic capacitors as close as possible to the load (47µF minimum). Maintaining low resistance and low inductance printed circuit board traces is important for connecting loads to the output pins of the converter. This is 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 your PCB. Input voltage ripple for various output voltages using four 47µF input ceramic capacitors. The same graph is shown in Figure B with one 470µF polymer capacitor (470m from Sanyo 6TPB) in parallel with two 47µF ceramic capacitors under full load.
The on/off pin (pin 1) is used to remotely turn the converter on or off with a system signal referenced to GND (pin 4). . To turn on the converter, the on/off pin should be at logic low or remain on, and to turn off the converter, the on/off pin should be at logic high or connected to VIN. The open/close pin is pulled down internally. A TTL or CMOS logic gate, open collector (drain) transistor can be used to drive the on/off pins. When using open collector (drain) transistors, add a 5K pull-up resistor (R) to 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 capable of: – Down to 1.2 mA at low level voltages. 0.8V - Supply up to 0.25mA at high logic levels of 2.3V - 5.5V.

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 trimmer pin (pin 3) and the GND pin (pin 4); note that when the trimmer resistor is not connected, The output voltage of the converter is 0.7525 V.

r Required value of trimmer resistor [kΩ] = -reqov 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 resistors in parallel 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 in between.

Protection Function Input Under-Voltage Lockout Input under-voltage lockout is standard on this converter. When the input voltage falls below a predetermined voltage, the converter will shut down; when 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 will turn off when the input voltage drops below 2.2 V. Output Over Current Protection (OCP) The converter is over current and short circuit protected. Once an overcurrent condition is detected, the converter will enter hiccup mode. Once the overload or short-circuit condition is removed, VOUT will return to its rated value.

Over Temperature Protection (OTP): The converter will shut down under over temperature conditions to protect itself from overheating caused by operation outside the thermal derating curve or operation under 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.
Characterization of general information converters are characterized in many aspects of operation, 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, response to Transient response to a load step change. GE, overload and short circuit. Where X represents different output voltages, (Y=1 represents vertical thermal derating, ...) will involve vertical thermal derating of all output voltages. The following pages contain specific plots or waveforms associated with the converter. Additional notes on specific data are provided below. Test Conditions: All data using converters soldered on test boards, specifically 0.060" thick four-layer printed wiring boards (PWB). No metallization on top and bottom layers. The two inner layers consist of two ounces of copper, with To provide traces to connect to the converter. Insufficient outer metallization and limited thermal connections ensure thermal requirements, a recognized fuse with a maximum rating of 15 amps must be used in series with the input line.
Characterization of general information converters are characterized in many aspects of operation, 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, response to Transient response to a load step change. GE, overload and short circuit. 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 will refer to vertical thermal derating of all output voltages. The following pages contain specific plots or waveforms associated with the converter. Additional notes on specific data are provided below. Test Conditions: All data using converters soldered on test boards, specifically 0.060" thick four-layer printed wiring boards (PWB). No metallization on top and bottom layers. The two inner layers consist of two ounces of copper, with To provide traces to connect to the converter. Insufficient 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 scenario for thermal derating. All measurements requiring airflow are performed in vertical and horizontal wind tunnels, using infrared (IR) thermal imaging cameras and thermocouples for temperature measurements. 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.

Thermal derating load current as a function of ambient temperature and airflow rate. X.1 to X.2, maximum temperature 120°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 mounting of converters. For each set of conditions, the maximum load current is defined as the lowest of: (i) the output current at which any MOSFET temperature does not exceed the maximum specified temperature of 120°C as shown in the thermal image, or (ii) the maximum current rating of the converter (5A). During normal operation, the derating curve for a maximum FET temperature of less than or equal to 120°C should not be exceeded. To operate within the derating curve, the printed circuit board temperature at the thermocouple location should not exceed 120°C.

Efficiency vs. load current plots at 25°C ambient temperature, 200 LFM (1m/s) airflow rate, and 4.5 V, 5.0 V, and 5.5 V input voltages. Efficiency vs. load current plot at 200 LFM (1m/s) airflow rate and 3.0 V, 3.3 V, and 3.6 V input voltages. Voltage≤2.5V.
Power Dissipation shows a plot of power dissipation versus load current at Ta = 25°C, airflow velocity of 200 lfm (1m/s), vertical mounting, and input voltages of 4.5 V, 5.0 V, and 5.5 V for 3.3v output. Ripple and Noise The output voltage ripple waveform is measured at full rated load current. Note that all output voltage waveforms are measured through 1µF ceramic capacitors. The output voltage ripple and input reflected ripple current waveforms were obtained with the test setup shown in Figure F.