BLM_P Series Overview
Provided by Murata Electronics, the BLM_P series chip ferrite beads benefit to suppress noise energy in high current circuits (a maximum 6A DC current on power lines) thanks to its low DC resistance. When comparing it with regular inductors, chip ferrite beads are capable of better absorbing noise due to their structure as ferrite materials have a high loss at high frequency. Besides, the BLM series can be used in circuits where the stable ground connection is not offered because the part doesn’t need one.
- Excellent high current noise suppression efficiency
- Wide operating temperature: -55°C ~ 125°C
- Compact structure building
- RoHS compliant
- Low DC impedance of 220Ω
- No ground power connection need
- Prominent solder heat resistance
Package Dimension in mm
- Core Material – Ferrite
- Operating Temperature – -55°C~125°C
- Tolerance – ±25%
- Resistance – 50mOhm
- Subcategory – Other Filters
- Shielding – Unshielded
- Construction – Chip Bead
- Frequency – 100MHz
- Max DC Current – 2A
- Filter Type – Power Line
- Number of Lines – 1
- DC Resistance (DCR) (Max) – 45mOhm
- Impedance @ Frequency – 220Ohm @ 100MHz
- No Radiation Hardening
- No SVHC
- ROHS3 Compliant
Where to Use
The BLM_P series chip ferrite beads are suitable for general signal noise suppression, EMI filtering, and used as ESD protect devices (anti electrostatic discharge components), etc.
Typical Circuit Layout
When using in Integrated Circuits (like MCU), ferrite beads chip is series-connected to signal lines and function to block noise for signal transmitting. While in power supplies, the ferrite bead is combined with bypass capacitors to form a low-pass filtering network to attenuate the high frequency noise to the ground. Below is the Murata ferrite beads’ specific usage of subcategories. From the table we learn that the BLM_P series we discussed today fits power lines noise depression better.
– Signal Waveforms Overshoot & Undershoot Issue
The resonance induced by the inductance of the errite beads and the static capacitance (input capacitance of the ICs, etc.) of the other portions of the circuits causes this phenomenon, which is more common with ferrite beads with a steep impedance curve. Inserting dampening resistors in series with the ferrite beads is one technique to ameliorate the issue. When damping resistors are inserted, the energy of the resonance is absorbed by the resistors, reducing the resonance and reducing both overshoot and undershoot.
However, because the usage of these damping resistors causes the voltage to drop in a similar manner, it is important to consider if the lower wave height of the signals is causing problems. The steeper the impedance curve of ferrite beads, the smaller the internal loss and the more probable resonance will occur; conversely, the gentler the impedance curve, the less likely resonance would occur. As a result, avoiding ferrite beads with a steeper curvature than necessary helps to reduce overshoot and undershoot.
– Rated Current Derating
For the BLM21PG series, current derating is required when the working temperature exceeds 85°C. According to the operating temperature, use the derating curve provided in the chart.
(Summarized by Easybom)
About the Manufacturer
Murata is leading enterprise that committed to designing, manufacturing and providing advanced electronic materials, leading edge electronic components, and multi-functional, high-density modules. Our innovations are able to be discovered in an extensive range of applications containing mobile phones, home appliances, and automotive applications to energy management systems and healthcare devices.
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