S100 Slave - NB IoT BC95


The S100 Slave - NB IoT BC95 is a certified Rhomb.io module which contains four variants: BC95-B8, BC95-B5, BC95-B20 and BC95-B28. It is designed to communicate with mobile network operators’ infrastructure equipment through the NB-IoT radio protocol (3GPP Rel. 13) with a high-performance NB-IoT module with extremely low power consumption. It supports multiple frequency bands and it is able to provide a complete range of SMS and data transmission services to meet client-side demands.

The next figure show a 3D view for the S100 Slave - NB IoT BC95.

S100 Slave - NB IoT BC95 Top.png

           S100 Slave - NB IoT BC95 Bottom.png


  • Smart metering
  • Bike sharing
  • Smart parking
  • Smart city
  • Security and asset tracking
  • Home appliances
  • Agricultural and enviroment monitoring

Module specification

The S100 Slave - NB IoT BC95 mounts the Quetel BC95, a narrowband IoT module with ultra-low power consumption (5 uA in power saving mode) and super high sensitivity compatible with Quectel GSM/GPRS modules.

The module supports multiple frequency bands depending on the assembled chip variant. The variant is marked in the bottom side of the module and its frequencies are shown in the following table:

Variants B5 B8 B20 B28
Frequency Band (MHz) 850 900 800 700
Region China, Korea Europe, China Europe Australia

There are two UART interfaces, one for communications with the module and one for debug. The debug UART (UART-DBG) is connected to two tesp-pads in the module, but it can also be connected to the Master module by assembling R1 and R2 resistors. The subscriber identity module (SIM) can be a nano SIM card with the SIM holder version or a embedded SIM in the eSIM version. There is a 50 Ω UMCC antenna connector RF signal.

One LED is assembled on the module in order to give status feedback to the user. The LED turn on when the module is attached to network and turn off when it is not working or it is not attached. The LED can be disabled by open the "LED" solder-jumper.

The module include a 10-bit ADC connected to "DIFF" signal (directly from Motherboard). The maximum input voltage should be lower than the VBAT voltage.

The following figure identifies the main components onboard.

S100 Slave - NB IoT BC95 Description Top.png
S100 Slave - NB IoT BC95 Description Bottom.png

The next figure shows the Block Diagram for the S100 Slave - NB IoT BC95:

S100 Slave - NB IoT BC95 Block Diagram.png
S100 Slave - NB IoT BC95Features
Quectel BC95 NB-IoT module compliant 3GPP Rel. 13
Embedded SIM or nano SIM options
Power consumption in PSM: 5 uA
Transmitting power: 23 dBm ± 2 dB
Suports IPv4/IPv6*/UDP/CoAP
Data transmission: 21.25 kbps (DL)/15.625 kbps (UL)
UART interface
Op. voltage: VSYS and VBAT
Op. temperature: -35ºC to +75ºC

User Interfaces

The following table indicates the available serial interfaces of the Rhomb.io standard used in this module. This table relates the interfaces of the Rhomb.io standard with the net names of the schematic and with the components to which they are connected.

Rhomb.io Interface Schematic Signal Component Component Pin Comments
UART-B UART-B_RXD BC95 (U1) DBG_RXD R1 must be assembled
UART-B_TXD DBG_TXD R2 must be assembled
  • UART: UART-A and UART-B interfaces are accessible through test-pads

GPIOs and Control Signals

The following table summarizes the GPIOs and Control Signals used on the S100 Slave - NB IoT BC95. This table relates the signals of the Rhomb.io standard with the net names of the schematic and with the components to which they are connected.

Rhomb.io Signal Schematic Signal Component Component Pin
1WIRE 1WIRE ID Memory (U2) IO
IO IO0 Linear Regulator (U3) EN
IO1 Load Switch (U5) EN
  • #RESET_IN: Reset the module.
  • 1WIRE: This signal can be used to read the ID Memory.
  • DIFF: 10-bit ADC signal from Motherboard.
  • INT: When an SMS message is received or data is transmitted, the module will output signals to inform DTE.
  • IO: IO0 and IO1 enable de linear regulator and the load switch required to supply the BC95 module.


The S100 Slave - NB IoT BC95 use the VSYS rail or the VBAT rail. You can choose the voltage enabling the linear regulator with IO0 signal for VSYS or enabling the load switch with IO1 signal for VBAT (by default both power sources are off). Make sure these rails are enabled on the motherboard you are going to plug this module and they can provide up to 0.5 A current.

The power consumption varies with different modes. See the BC95 datasheet to find more information about power consumption.

S100 Slave - NB IoT BC95 Consumption.png



Click the image below to download the schematic files.

Bill of materials

Click the image below to download the BOM files.

Fabrication files

Click the image below to download the fabrication files.

Mechanical Specifications

S100 Slave - NB IoT BC95 Dimensions.png

Due to the components on the bottom side exceed the 0.8 mm height that the Rhomb.io standard defines between the Motherboard PCB and the Modules PCB for the correct connection between them, a stacked Adapter is required to use this module.


  • Precaution against Electrostatic Discharge. When handling Rhomb.io products, ensure that the environment is protected against static electricity. Follow the next recommendations:
  1. The users should wear anti-static clothing and use earth band when manipulating the device.
  2. All objects that come in direct contact with devices should be made of materials that do not produce static electricity that would cause damage.
  3. Equipment and work table must be earthed.
  4. Ionizer is recommended to remove electron charge.
  • Contamination. Be sure to use semiconductor products in the environment that may not be exposed to dust or dirt adhesion.
  • Temperature/Humidity. Semiconductor devices are sensitive to environment temperature and humidity. High temperature or humidity may deteriorate semiconductor devices characteristics. Therefore avoid storage or usage in such conditions.
  • Mechanical Shock. Care should be exercised not to apply excessive mechanical shock or force on the connectors and semiconductors devices.
  • Chemical. Do not expose semiconductor device to chemical because reaction to chemical may cause deterioration of device characteristics.
  • Light Protection. In case of non-EMC (Epoxy Molding Compound) package, do not expose semiconductor IC to strong light. It may cause devices malfunction. Some special products which utilize the light or have security function are excepted from this specification.
  • Radioactive, Cosmic and X-ray. Semiconductor devices can be influenced by radioactive, cosmic ray or X-ray. Radioactive, cosmic and X-ray may cause soft error during device operation. Therefore semiconductor devices must be shielded under environment that may be exposed to radioactive, cosmic ray or X-ray.
  • EMS (Electromagnetic Susceptibility). Note that semiconductor devices characteristics may be affected by strong electromagnetic waves or magnetic field during operation.


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