GM3490E

GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 1. Feature 3. General Description ● Devices in the GM3485E family (GM3488E/ GM3490E/ GM3491E) are ±15kV ESD-protected, +3.3V, low-power transceivers for RS-422 communications. Each device contains one driver and one receiver. The GM3488E feature slew-rate-limited drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission at data rates up to 1Mbps. The GM3490E, and GM3491E transmit at up to 12Mbps. ESD Protection for RS-485 I/O Pins • ±15kV—Human Body Model • ±8kV—IEC 1000-4-2, Contact Discharge ● ● ● ● ● ● • ±15kV—IEC 1000-4-2, Air-Gap Discharge Operate from a Single +3.3V Supply— No Charge Pump Required Interoperable with +5V Logic Guaranteed 12Mbps Data Rate (GM3490E/GM3491E) Slew-Rate Limited for Error less Data Transmission (GM3488E) -7V to +12V Common-Mode Input Voltage Range Current-Limiting and Thermal Shutdown for Driver Overload Protection 2. APPLICATIONS ● ● ● ● ● Telecommunications Industrial-Control Local Area Networks Transceivers for EMI-Sensitive Applications Integrated Services Digital Networks Packet Switching All devices feature enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 Air-Gap Discharge, ±8kV using IEC 1000-4-2 Contact Discharge, and ±15kV using the Human Body Model. Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if both inputs are open circuit. The GM3488E, GM3490E, and GM3491E feature full duplex communication. Figure 1 Simplified Schematic www.gmmicro.com Copyright © GATEMODE Corp. -1- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 4. Specifications 4.1 ABSOLUTE GMIMUM RATINGS Parameter VCC Description MIN Supply Voltage MAX UNIT +7 V RE , DE Control Input Voltage -0.3 +7 V DI Driver Input Voltage -0.3 +7 V A, B,Y,Z Driver Output Voltage -7.5 +12.5V V A, B Receiver Input Voltage -7.5 +12.5V V RO Receiver Output Voltage 0.3 VCC+0.3V Storage Temperature Range -65 150 °C 4.2 DC ELECTRICAL CHARACTERISTICS (VCC = +3.3V ±0.3V, TA = TMIN to TGM, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Differential Driver Output CONDITIONS MIN RL = 100Ω (RS-422), Figure 4 2.0 RL = 54Ω (RS-485), Figure 4 1.5 RL = 60Ω (RS-485), VCC = 3.3V, Figure 5 1.5 SYMBOL VOD TYP MAX UNIT V Change in Magnitude of Driver Differential Output Voltage for Complementary △VOD R = 54Ω or 100Ω, Figure 4 0.2 V VOC R = 54Ω or 100Ω, Figure 4 3 V △VOC R = 54Ω or 100Ω, Figure 4 0.2 V Output States(Note 1) Driver Common-Mode Output Voltage Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States Input High Voltage VIH DE, DI, RE Input Low Voltage VIL DE, DI, RE 0.8 V Input Current IIN1 DE, DI, RE VCC floating ±2 µA Input Current (A, B) IIN2 Output Leakage (Y, Z) IO Output Leakage (Y, Z) in Shutdown Mode Receiver Differential Threshold Voltage Receiver Input Hysteresis Receiver Output High Voltage www.gmmicro.com Copyright © GATEMODE Corp. IO VTH △VTH VOH 2.0 V DE = 0V; VIN = 12V 1.0 VCC = 0V or 3.6V VIN = -7V -0.8 DE = 0V, RE = 0V, VOUT = 12V 100 VCC= 0V or 3.6V, GM3491E VOUT = -7V -100 VOUT = 12V 100 VCC= 0V or 3.6V, GM3491E VOUT = -7V -100 DE = 0V, RE = 3.6V, -0.2 -7V≤VCM ≤12V 0.2 50 VCM = 0V IO = -4mA, VID = 200mV,Figure 6 -2- VCC-0.4 mA µA µA V mV V Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers DC ELECTRICAL CHARACTERISTICS(continued) (VCC = +3.3V ±0.3V, TA = TMIN to TGM, unless otherwise noted. Typical values are at TA = +25°C.) MAX UNIT IO = 4mA, VID = -200mV,Figure 6 0.4 V IOZR VCC = 3.6V, 0V ≤ VOUT ≤ VCC ±1 µA Receiver Input Resistance RIN -7V ≤ VCM ≤ 12V Supply Voltage Range VCC PARAMETER SYMBOL Receiver Output Low Voltage VOL Three-State (high impedance) Output Current at Receiver Supply Current Supply Current in Shutdown Mode Driver Short-Circuit Current Receiver Short-Circuit Output Current ESD Protection for Y, Z, A, B ICC ISHDN IOSD IOSR CONDITIONS TYP 96 kΩ 3.0 No load, DI = 0 or VCC 3.6 DE = VCC, RE = 0 or VCC 0.5 DE = 0V, RE = 0 0.45 0.9 1.3 2 1.0 VOUT = -7V -250 VOUT = 12V 250 ±8 0V ≤ VO ≤ VCC ±60 IEC 1000-4-2 Air Discharge ±15 IEC 1000-4-2 Contact Discharge (GM3491E) ±8 IEC 1000-4-2 Contact Discharge (GM3490E, Human Body Model -3- V mA DE = 0, RE = VCC, DI = VCC or 0 GM3488E) www.gmmicro.com Copyright © GATEMODE Corp. MIN ±8 µA mA mA KV ±15 Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 4.3 Switching Characteristics—GM3490E/GM3491E (VCC = +3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS Maximum Data Rate Driver Differential Output Delay Driver Differential Output Transition Time Driver Propagation Delay, Low-to-High Level Driver Propagation Delay, High-to-Low Level MIN TYP 12 15 MAX UNITS Mbps tDD RL = 60Ω, Figure 7 1 22 35 ns tDD RL = 60Ω, Figure 7 3 11 25 ns tPLH RL = 27Ω, Figure 8 7 23 35 ns tPHL RL = 27Ω, Figure 8 7 23 35 ns tPDS RL = 27Ω, Figure 8 -1.4 ±8 ns |tPLH - tPHL| Driver Propagation Delay Skew (Note 2) DRIVER-OUTPUT ENABLE/DISABLE TIMES (GM3491E only) Driver-Output Enable Time to Low Level Driver-Output Enable Time to High Level Driver-Output Disable Time from High Level Driver-Output Disable Time from Low Level Driver-Output Enable Time from Shutdown to Low Level Driver-Output Enable Time from Shutdown to High Level www.gmmicro.com Copyright © GATEMODE Corp. tPZL RL = 110Ω, Figure 10 42 90 ns tPZH RL = 110Ω, Figure 9 42 90 ns tPHZ RL = 110Ω, Figure 9 35 80 ns tPLZ RL = 110Ω, Figure 10 35 80 ns tPSL RL = 110Ω, Figure 10 650 900 ns tPSH RL = 110Ω, Figure 9 650 900 ns -4- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 4.4 SWITCHING CHARACTERISTICS—GM3488E (VCC = +3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN Delay Driver Differential Output Transition Time Driver Propagation Delay, Low-to-High Level Driver Propagation Delay, High-to-Low Level MAX 1000 Maximum Data Rate Driver Differential Output TYP UNITS Kbps tDD RL = 60Ω, Figure 7 200 300 500 ns tDD RL = 60Ω, Figure 7 150 240 400 ns tPLH RL = 27Ω, Figure 8 200 300 500 ns tPHL RL = 27Ω, Figure 8 200 300 500 ns tPDS RL = 27Ω, Figure 8 ±50 tPZL RL = 110Ω, Figure 10 300 500 ns tPZH RL = 110Ω, Figure 9 150 400 ns tPHZ RL = 110Ω, Figure 9 50 80 ns tPLZ RL = 110Ω, Figure 10 50 80 ns tPSL RL = 110Ω, Figure 10 1.9 2.7 µs tPSH RL = 110Ω, Figure 9 2.2 3.0 µs |tPLH - tPHL| Driver Propagation Delay Skew ns (Note 2) Driver-Output Enable Time to Low Level Driver-Output Enable Time to High Level Driver-Output Disable Time from High Level Driver-Output Disable Time from Low Level Driver-Output Enable Time from Shutdown to Low Level Driver-Output Enable Time from Shutdown to High Level 4.5 NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICS Note 1: ∆VOD and ∆VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 2: Measured on |tPLH (Y) - tPHL (Y)| and |tPLH (Z) - tPHL (Z)|. Note 3: The transceivers are put into shutdown by bringing high RE and DE low. If the inputs are in this state for less than 80ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section. www.gmmicro.com Copyright © GATEMODE Corp. -5- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 4.6 Pin Description PIN GM3488E GM3490E GM3491E SOP8 SOP14 2 2 RO — 3 RE NAME FUNCTION Receiver Output: If A > B by 200mV, RO will be high; If A < B by 200mV, RO will be low. Receiver Output Enable. RO is enabled when RE is low; RO is high impedance when RE is high. Driver Output Enable. The driver outputs, Y and Z, are enabled by bringing DE high. They are high impedance when — 4 DE DE is low. If the driver outputs are enabled, the parts function as line drivers. While they are high impedance, they function as line receivers if RE is low. Driver Input. A low on DI forces output Y low and output Z 3 5 DI high. Similarly, a high on DI forces output Y high and output Z low. 4 6, 7 GND 5 9 Y Non-inverting Driver Output 6 10 Z Inverting Driver Output — — A 8 12 A Non-inverting Receiver Input — — B Inverting Receiver Input and Inverting Driver Output 7 11 B Inverting Receiver Input 1 14 VCC — 1, 8, 13 N.C. www.gmmicro.com Copyright © GATEMODE Corp. Ground Non-inverting Receiver Input and Non-inverting Driver Output Positive Supply: 3.0V ≤ VCC ≤ 5.5V. Do not operate device with VCC > 5.5V No Connect—not internally connected -6- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Figure 2. GM3488E/GM3490E Pin Configuration and Typical Operating Circuit Figure 3. GM3491E Pin Configuration and Typical Operating Circuit www.gmmicro.com Copyright © GATEMODE Corp. -7- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Figure 4. Driver VOD and VOC Figure 5. Driver VOD with Varying Common-Mode Voltage Figure 6. Receiver VOH and VOL Figure 7. Driver Differential Output Delay and Transition Times www.gmmicro.com Copyright © GATEMODE Corp. -8- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Figure 8. Driver Propagation Times Figure 9. Driver Enable and Disable Times (tPZH, tPSH, tPHZ) Figure 10. Driver Enable and Disable Times (tPZL, tPSL, tPLZ) www.gmmicro.com Copyright © GATEMODE Corp. -9- Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Figure 11. Receiver Propagation Delay Figure 12. Receiver Enable and Disable Times Note 4: The input pulse is supplied by a generator with the following characteristics: f = 250kHz, 50% duty cycle, tr ≤ 6.0ns, ZO = 50Ω. Note 5: CL includes probe and stray capacitance. www.gmmicro.com Copyright © GATEMODE Corp. - 10 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 5. Function Tables 5.1 Devices with Receiver/Driver Enable (GM3491E) Table 1. Transmitting INPUTS OUTPUTS RE DE DI B* A* × × 0 1 1 1 0 0 1 0 × × 0 1 High-Z High-Z 1 0 High-Z High-Z MODE Normal Normal Normal Shutdown * B and A outputs are Z and Y, respectively, for full-duplex part (GM3491E). X = Don’t care; High-Z = High impedance Table 2. Receiving INPUTS OUTPUTS MODE RE DE A,B RO × 1 ≧ +0.2V 1 Normal × 1 0 Normal 0 1 0 0 ≦ -0.2V Inputs Open × 1 High-Z Normal Shutdown * DE is a “don’t care” (x) for the full-duplex part (GM3491E). X = Don’t care; High-Z = High impedance 5.2 Devices without Receiver/Driver Enable(GM3488E/GM3490E) Table 3. Transmitting INPUT DI 1 0 www.gmmicro.com Copyright © GATEMODE Corp. Table 4. Receiving OUTPUTS Z Y 0 1 1 0 INPUT A,B ≧ +0.2V ≦ -0.2V Inputs Open - 11 - OUTPUT RO 1 0 1 Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 6. Applications Information TheGM3488E/GM3490E/GM3491E are low-power transceivers for RS-485 and RS-422 communications. The GM3488E can transmit and receive at data rates up to 1Mbps, and the GM3490E/GM3491E at up to 12Mbps. The GM3488E/GM3490E/GM3491E are full-duplex transceivers, Driver Enable (DE) and Receiver Enable (RE) pins are included on the GM3491E. When disabled, the driver and receiver outputs are high impedance. 7. Reduced EMI and Reflections(GM3488E) The GM3488E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 13 shows the driver output waveform of a GM3490E/GM3491E transmitting a 125kHz signal, as well as the Fourier analysis of that waveform. High-frequency harmonics with large amplitudes are evident. Figure 14 shows the same information, but for the slew-rate-limited GM3488E transmitting the same signal. The high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced. 8. Low-Power Shutdown Mode(GM3491E) A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled (high impedance). In shutdown, the devices typically draw only 1.3uA of supply current.For these devices, the tPSH and tPSL enable times assume the part was in the low-power shutdown mode; the tPZH and tPZL enable times assume the receiver or driver was disabled, but the part was not shut down. Figure 13. Driver Output Waveform and FFT Plot of Figure 14. Driver Output Waveform and FFT Plot of GM3488E GM3490E/GM3491E Transmitting a 125kHz Signal Transmitting a 125kHz Signal Figure 15. GM3490E/GM3491E Driver Propagation Delay Figure 16. GM3490E/GM3491E Receiver Propagation Delay Driven by External RS-485 Device www.gmmicro.com Copyright © GATEMODE Corp. - 12 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Figure 17. GM3488E Driver Propagation Delay Figure 18. GM3488E Receiver Propagation Delay Figure 19. GM3488E System Differential Voltage at 125kHz Figure 20. GM3490E/GM3491E System Differential Voltage at Driving 4000 Feet of Cable 125kHz Driving 4000 Feet of Cable 9. Driver Output Protection Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A fold-back current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range. In addition, a thermal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively. 10. Propagation Delay Figures 15–18 show the typical propagation delays. Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle). The receiver skew time, |tPRLH - tPRHL|, is under 10ns 20ns for the GM3488E). The driver skew times are 8ns for the GM3490E/GM3491E. 11. Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 21 for an example of a line repeater. Figures 19 and 20 show the system differential voltage for parts driving 4000 feet of 26AWG twisted-pair wire at 125kHz into 120Ω loads. For faster data rate transmission, please consult the factory. www.gmmicro.com Copyright © GATEMODE Corp. - 13 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Figure 21. Line Repeater for GM3488E/GM3490E/GM3491E 12. ±15kV ESD Protection ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the GM3485E family of devices have extra protection against static electricity. Engineers have developed state-of the-art structures to protect these pins against ESD of ±15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to the following limits: 1) ±15kV using the Human Body Model 2) ±8kV using the Contact-Discharge method specified in IEC 1000-4-2 3) ±15kV using IEC 1000-4-2’s Air-Gap method. 13. ESD Test Conditions ESD performance depends on a variety of conditions. Contact us for a reliability report that documents test setup, test methodology, and test results. 14. Human Body Model Figure 22a shows the Human Body Model and Figure 22b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. www.gmmicro.com Copyright © GATEMODE Corp. - 14 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 15. IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The GM3485E family of devices helps you design equipment that meets Level 4 (the highest level) of IEC 1000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 1000-4-2 is higher peak current in IEC 1000-4-2, because series resistance is lower in the IEC 1000-4-2 model. Hence, the ESD withstand voltage measured to IEC 1000-4-2 is generally lower than that measured using the Human Body Model. Figure 23a shows the IEC 1000-4-2 model, and Figure 23b shows the current waveform for the ±8kV IEC 1000-4-2, Level 4 ESD contact-discharge test. The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized. Figure 22a. Human Body ESD Test Model Figure 22b. Human Body Current Waveform Figure 23a. IEC 1000-4-2 ESD Test Model Figure 23b. IEC 1000-4-2 ESD Generator Current Waveform 16. Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. of course, all pins require this protection, not just RS-485 inputs and outputs. www.gmmicro.com Copyright © GATEMODE Corp. - 15 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers 17. Typical Applications The GM3488E/GM3490E/GM3491E transceivers are designed for bidirectional data communications on multi point bus transmission lines. Figures 24 show typical net work applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 21. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited GM3488E is more tolerant of imperfect termination. Figure 24. GM3488E/GM3490E/GM3491E Full-Duplex RS-485 Network www.gmmicro.com Copyright © GATEMODE Corp. - 16 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers SOP-8L MILLIMETER SYMBOLS MIN NOM MAX A 1.5 - 1.7 A1 0.1 - 0.25 A2 1.3 1.4 1.5 b 0.33 0.4 0.47 C 0.2 - 0.25 D 4.7 4.9 5.1 E 5.9 6 6.1 E1 3.8 3.9 4 e 1.27(BSC) L 0.55 0.6 0.75 L1 1.05(BSC) θ 0° 4° 8° www.gmmicro.com Copyright © GATEMODE Corp. - 17 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers SOP-14 MILLIMETER SYMBOLS MIN NOM MAX A - - 1.75 A1 0.05 - 0.225 A2 1.30 1.40 1.50 A3 0.60 0.65 0.70 b 0.39 - 0.47 b1 0.38 0.41 0.44 c 0.20 - 0.24 c1 0.19 0.20 0.21 D 8.55 8.65 8.75 E 5.80 6.00 6.20 E1 3.80 3.90 4.00 e 1.24BSC h 0.25 - 0.50 L 0.50 - 0.80 L1 θ www.gmmicro.com Copyright © GATEMODE Corp. 1.05REF 0° - - 18 - 8° Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Order Information Order number Package Marking information Operation Temperature Range MSL Grade Ship, Quantity Green GM3488ESA SOP8 GM3488E -40 to 85°C 3 T&R, 2500 Rohs GM3490ESA SOP8 GM3490E -40 to 85°C 3 T&R, 2500 Rohs GM3491ESA SOP14 GM3491E -40 to 85°C 3 T&R, 2500 Rohs www.gmmicro.com Copyright © GATEMODE Corp. - 19 - Tel: (+86) 13135660803 Email: sales@gmmicro.com GM3488E/GM3490E/GM3491E Low-Power,RS-485/RS-422 Transceivers Version modification record version Modify the description page time Modify personnel On June 21,2024 Fan 1.Original:GM3490_GM3491_1.0 → GM3490_GM3491_1.1 2.Input Current testing environment.Increase the VCC Floating 3.Output Leakage (Y, Z) 1.1 VOUT = 12V environment MAX=20uA → MAX=100uA. VOUT = -7V environment MAX=-20uA → MAX=-100uA. 2 4.Output Leakage (Y, Z) in Shutdown Mode, testing environment RE =0V → RE =5V, VOUT = 12V environment. MAX=1uA → MAX=100uA. VOUT = -7V environment MAX=-1uA → MAX=-100uA. www.gmmicro.com Copyright © GATEMODE Corp. - 20 - Tel: (+86) 13135660803 Email: sales@gmmicro.com