Product Info

NB-IoT Module Series
BC660K-GL Hardware Design
BC660K-GL_Hardware_Design
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Figure 15: Reference Circuit with Transistor Circuit
1. VDD_EXT cannot pull up MAIN_RXD directly. Due to the anti-backflow design of the MAIN_RXD pin,
MAIN_RXD pin can be directly connected to the TXD of DTE in the 1.8–3.3 V voltage domain. If the
Deep Sleep/Light Sleep mode wake-up function of the MAIN_RXD is enabled, it is recommended
that MAIN_RXD does not use a level conversion circuit to avoid abnormal wake-up.
2. If you choose the transistor conversion circuit, don’t mount the R1 marked in red.
3. If VDD_EXT need pull up the module MAIN_RXD, you need to connect a Schottky diode in series
first, and then pull up the module MAIN_RXD through a 4.7-20 kΩ resistor. For more details, see
document [3].
4. Transistor circuit solution is not suitable for applications with high baud rates exceeding 460 kbps.
3.8. (U)SIM Interface
The (U)SIM card is powered by an internal regulator in the module. Both 1.8 V and 3.0 V (U)SIM cards
are supported.
Table 11: Pin Definition of (U)SIM Interface
Pin Name
Pin
No.
Description
Comment
(U)SIM_VDD
14
(U)SIM card power supply
When 3.0 V ≤ VBAT ≤ 4.3 V, support
1.8/3.0 V (U)SIM card;
When 2.2 V ≤ VBAT < 3 V, only support
1.8 V (U)SIM card;
Maximum supply current: about 80 mA.
NOTES