Product Overview
Description
Product Description
The HT1200M is a single-chip, CMOS modem for use in Highway Addressable Remote Transducer (HART) field instruments and masters. The modem and a few external passive components provide all of the functions needed to satisfy HART physical layer requirements including modulation, demodulation, receive filtering, carrier detect and transmit-signal shaping. The HT1200M is pin-compatible with the SYM20C15. See the Pin Description and Functional Description sections for details on pin compatibility with the SYM20C15.
The HT1200M uses Phase Continuous Frequency Shift Keying (FSK) at 1200 bits per second. To conserve power the receive circuits are disabled during transmit operations and vice versa. This provides the half-duplex operation used in HART communications.
Specification
Application
Table 1 HT1200M Pin Descriptions | ||||||||
Signal | Type | PLCC | LQFP | Description | ||||
TEST1 | input | 1 | 28 | Connect to Vss. | ||||
TEST2 | — | 2 | 29 | No connect. | ||||
TEST3 | — | 3 | 31 | No connect. | ||||
TEST4 | — | 4 | 32 | No connect. | ||||
TEST5 | input | 5 | 1 | Connect to Vss. | ||||
INRESET | input | 6 | 2 | Reset all digital logic when low | ||||
TEST7 | input | 7 | 3 | Connect to Vss. | ||||
TEST8 | input | 8 | 4 | Connect to Vss. | ||||
TEST9 | input | 9 | 5 | Connect to Vss. | ||||
OTXA | output | 10 | 7 | Modulated output transmit and transmit signal to 4-20mA loop. FSK modulated HART interface circuit. | ||||
IAREF | input | 11 | 8 | Analog reference voltage. | ||||
ICDREF | input | 12 | 9 | Carrier detect reference voltage. | ||||
OCBIAS | output | 13 | 10 | Comparator bias current. | ||||
TEST10 | input | 14 | 11 | Connect to Vss. | ||||
VDDA | power | 15 | 13 | Analog supply voltage. | ||||
IRXA | input | 16 | 14 | FSK modulated HART receive signal from 4-20mA loop interface circuit | ||||
ORXAF | output | 17 | 15 | Analog receiver filter input. | ||||
IRXAC | input | 18 | 16 | Analog receive comparator input. | ||||
OXTL | output | 19 | 17 | Crystal oscillator output. | ||||
IXTL | input | 20 | 18 | Crystal oscillator input. | ||||
VSS | ground | 21 | 6,20 | Ground. | ||||
VDD | power | 22 | 21,30 | Digital supply voltage. | ||||
INRTS | input | 23 | 22 | Request to send. | ||||
ITXD | input | 24 | 23 | Input transmit data. Transmitted HART data stream from UART. | ||||
TEST11 | — | 25 | 24 | No connect. | ||||
ORXD | output | 26 | 25 | Received demodulated HART data to UART. | ||||
OCD | output | 27 | 26 | Carrier detect output. | ||||
TEST12 | — | 28 | 27 | No connect. | ||||
VSSA | ground | — | 12,19 | Analog ground | ||||
Pin Description
IAREF: Analog Reference Voltage
This analog input sets the do operating point of the operational amplifiers and comparators and is usually selected to split the do potential between VDD and Vss. IAREF in DC Characteristics refer to Electrical Characteristics.
ICDREF: Carrier Detect Reference Voltage
This analog input controls at which level the carrier detect (OCD) becomes active. This is determined by the do voltage difference between ICDREF and IAREF. Selecting ICDREF-IAREF equal to 0.08 VDC will set the carrier detect to a nominal 100 mVp-p.
INRESET: Reset Digital Logic
When at logic low (VSS) this input holds all the digital logic in Reset. During normal operation INRESET should be at VDD. INRESET should be held low for a minimum of 10 ns after VDD=2.5 V as shown in picture.
INRTS: Request To Send
This active-low input selects the operation of the modulator. OTXA is enabled when this signal is low. This signal must be held high during power-up.
IRXA: Analog Receive Input
This input accepts the 1200/2200 Hz signals from the external filter.
IRXAC: Analog Receive Comparator Input
This is the positive input of the carrier detect comparator and the receiver filter comparator.
ITXD: Digital Transmit Input(CMOS)
This input to the modulator accepts digital data in NRZ form. When ITXD is low, the modulator output frequency is 2200 Hz. When ITXD is high, the modulator output frequency is 1200 Hz.
IXTL: Oscillator Input
This input to the internal oscillator must be connected to a parallel mode 460.8 kHz ceramic resonator when using the internal oscillator or grounded when using an external 460.8 kHz clock signal.
OCBIAS: Comparator Bias Current
The current through this output controls the operating parameters of the internal operational amplifiers and comparators. For normal operation, OCBIAS current is set to 2.5 uA.
OCD: Carrier Detect Output
This output goes high when a valid input is recognized on IRXA. If the received signal is greater than the threshold specified on ICDREF for four cycles of the IRXA signal, the valid input is recognized.
ORXAF: Analog Receive Filter Output
This signal is the square wave output of the receiver high-pass filter.
ORCD: Digital Receive Output (CMOS)
This signal outputs the digital receive data. When the received signal (IRXA) is 1200 Hz, ORXD outputs logic high. When the received signal (IRXA) is 2200 Hz, ORXD outputs logic low. ORXD is qualified internally with OCD and is logic high when OCD is low.
OTXA: Analog Transmit Output
This output provides the trapezoidal signal controlled by ITXD. When ITXD is low, the output frequency is 2200 Hz. When ITXD is high, the output frequency is 1200 Hz. This output is active when INRTS is low and 0.5 VDD when INRTS is high.
OXTL: Oscillator Output
This output from the internal oscillator must be connected to an external 460.8 kHz clock signal or to a parallel mode 460.8 kHz ceramic resonator when using the internal oscillator.
TEST(12: 1): Test Pin
These are test pins. For normal operation, tie these signals as per Table1.
VDD: Digital Power
This is the power for the digital modem circuitry.
VDDA: Analog Supply Voltage
This is the power for the analog modem circuitry.
VSS: Ground
This is the analog and digital ground.
VSSA: Analog Ground
Analog Ground
Packing & Delivery
Company Profile
* Microcyber is the member of FCG (FieldComm Group) and the Profibus National Organization (PNO).
* Microcyber has ISO 9001 certification.
* As a Development Services Provider, Microcyber provides extraordinary services and solutions of Foundation Fieldbus technology.
* Many of our products have passed FF certification, PA certification, HART certification, and NEPSI explosion-proof
certification, etc.
* Microcyber has ISO 9001 certification.
* As a Development Services Provider, Microcyber provides extraordinary services and solutions of Foundation Fieldbus technology.
* Many of our products have passed FF certification, PA certification, HART certification, and NEPSI explosion-proof
certification, etc.
* Microcyber has participated in many significant international exhibitions, such as ISA, Automation World, CIIF, Hannover
Method, Automation Expo and MICONEX.
* Microcyber will keep moving on and hope to meet you in the near future.
Method, Automation Expo and MICONEX.
* Microcyber will keep moving on and hope to meet you in the near future.
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