feature

Ultra-low series resistance

for higher current handling

low capacitance

Low series resistance

Lead-free options available

application

RF and computer designs require circuit protection, high-speed switching, and voltage clamping. Package leader code identification (top view)

illustrate

Schottky HBAT-5400 series diodes, commonly known as clamp diode circuits and waveforms optimized to preserve high-speed switching applications. The low series resistance, RS, makes them ideal for protecting sensitive circuits against transients conducted on data lines by high current components. Using a picosecond switch, the HBAT-540x responds to noise with a rise time of 1 nanosecond. Low capacitance minimizes waveform loss caused by signal degradation.

absolute maximum ratio

Note:

1. Operation beyond one of these conditions may result in permanent damage to the device.

Note:

2. To efficiently model the packaged HBAT-540x product, please refer to Application Note AN1124.

HBAT-540x DC electrical specification, TA=+25 degrees[1]

notes:

1. TA=+25°C, where TA is defined as the temperature at the package pins in contact with the circuit board.

2. The packaging marking code is laser marking.

3. IF = 100 mA; 100% test

4. IF = 100µA; 100% test

5. VF=0; f=1MHz

6. Measured by Kacol method at 20 mA guaranteed by design.

application information

Schottky Diode Fundamentals The HBAT-540x series shears/clamping diodes are Schottky devices. A Schottky device is a metal-semiconductor rectifying contact formed between metal n-doped or p-doped semiconductors. When a metal-semiconductor junction is formed, free electrons flow through the semiconductor junction to fill the free-energy state of the metal. This flow of electrons creates a loss or potential across the intersection. The difference in energy levels between semiconductors and metals is called a Schottky barrier. P-doped Schottky barrier diodes excel in applications that require ultra-low turn-on voltages (such as zero-bias RF detectors). But very low breakdown voltage and high series resistance are not suitable for clipping and clamping applications, including high forward current and high reverse voltage. Therefore, this discussion will focus entirely on nitrogen-doped Schottky diodes. Under forward bias (metal connected to an n-doped Schottky), or forward voltage, VF, there is a lot of energy for electrons that are hot enough to pass through the barrier and into the metal. Once the applied deviation exceeds the built-in junction potential, the forward current, if, will increase with a rapid increase in ventricular fibrillation.

When the Schottky diode is reverse biased, the potential electron barrier becomes large; therefore, having a small electron will have enough thermal energy to pass through the intersection. Reverse leakage current will be in the milliamp to microamp range, depending on diode type, reverse voltage and temperature. Compared to conventional pn Schottky junction current diodes can only be carried by the majority of the carrier. Because there is no minority carrier charge storage effect, Schottky diodes now have carrier lifetimes of less than 100 ps and switch semiconductors extremely fast. Schottky diodes are used as rectifiers at frequencies higher than 50ghz. Another significant difference between a Schottky diode and a pn diode is the forward voltage drop. Schottky diodes have a 0.6v voltage diode with a threshold typically 0.3Vp-n junction. See Figure 6.

Through careful manipulation of Schottky diameter contacts and metal selective deposition on N-doped silicon, the important characteristics of diodes (junction capacitance, parasitic series resistance; breakdown voltage, VBR; and forward voltage, VF,) can be tailored to specific applications optimization. The HSMS-270x series and HBAT-540x series diodes are just right. Both diodes have similar barrier heights; this corresponds to the value of the saturation current. However, different contact diameters and epilayer thicknesses result in different connection value capacitances, CJ and RS. This is described by the fragrance parameters in Table 1.

The forward voltage diodes are nearly identical for both at low values of IF ≤ 1 mA. However, when the current rises to 10mA, the low series resistance of the HSMS-270x is well below the forward voltage. This gives the HSMS-270x a higher current handling capability. The trade-off is higher value junction capacitance. The forward voltage and current diagrams illustrate the difference between the two Schottky diodes, as shown in Figure 7.

Because the equipment for assembly is automatically selected and placed, the two diodes from adjacent locations on the wafer go into the HBAT-5402 or HBAT-540C (series paired) for a tight fit - no additional cost for testing and boxing. Current clip handling/clamping circuit clamp diodes are used to handle high currents and protect precision circuit diodes downstream. Current processing power has been determined based on two sets of characteristics, those of the chip or the device itself and those of the package mounted on it.

Consider the circuit shown in Figure 8 below, two of which are Schottky diodes used to protect the digital data stream from noise peaks on the circuit. The ability to limit the voltage of diode spikes is related to the current spikes they sink. The current importance processing capability is shown in Figure 9, and the voltage and current generated in the forward direction are compared to 2 diodes. The first is the conventional 7.7 ohm Schottky diode used in the RF circuit. The second is a Schottky diode with the same characteristics, saving 1.0Ω of RS. For conventional diodes a high value of RS causes the voltage across the diode to rise as the current increases. The power loss in the diode heats the joint, causing the RS to climb, resulting in a runaway thermal condition. The voltage across the diode terminals does not occur in the second low resistance diode and even remains at a lower limit at high current values. Maximum reliability in the Schottky diode state is maintained at or below 150°C junction temperature, although brief trips to higher junction temperatures can be tolerated with no meaningful effect on mean time to failure, MTTF. To calculate the junction temperature, equation (1) and (3) below must be solved simultaneously.

IF=forward current

IS = saturation current

VF=forward voltage

RS = series resistance

TJ=junction temperature

Saturation current at IO=25°C

n = diode ideality factor

θJC=thermal resistance

Junction Box (Diode Lead)

= θ package + θ chip

TA = ambient (diode lead)

temperature

Equation (1) describes Schottky's ward VI curve diode. Equation (2) provides the saturation value of the diode current, which value is inserted into (1). Equation (3) gives

Junction temperature value

Power dissipation as a function of diode and ambient (lead) temperature.

The key factors in these equations are: RS, the series resistance of the diode that generates heat under high current conditions; theta chip, the thermal resistance of the chip, and the thermal resistance of the theta package, or package. The HBAT-540x series diodes are typically 2.4Ω, other than the HSMS-270x series, which are the lowest Schottky diodes available. Chip thermal resistance is typically 40°C/W; thermal iron alloy leadframe SOT-23 package resistance is typically 460°C/W; and SOT-323 package copper leadframe resistance is typically 110°C/W. The thermal resistance that affects the current handling capability of these diodes can be seen in Figures 3 and 4. Here, the calculated values of junction temperature and forward current show three ambient temperature values. The SOT-323 product, with its copper lead frame, allows safe operation of almost twice the current of a larger SOT-23 diode. Note that the term "ambient temperature" refers to the leads of the diode, not the surrounding air circuit board. It can be seen that the HBAT-540B and HBAT-540C products in the SOT-323 package will safely withstand steady state progress when keeping the diode terminals at 75°C. For pulsed current and transient current peaks less than 1 µs duration junctions do not have time to reach thermal steady state. Additionally, the diode junction can be brought to higher temperatures below 150°C for short periods of time without affecting device MTTF. Because of these factors, higher currents can be handled safely. The HBAT-540x series has the second highest current handling performance of any Agilent diode, next to the HSMS-270x series.

NOTE: For lead-free options, the part number will have the character "G" at the end, eg HBAT-540x-TR2G for 10000 lead-free reels