ZHCSFT4A March 2016 – August 2016 ISO7820LL , ISO7821LL
PRODUCTION DATA.
The ISO782xLL is a family of isolated LVDS buffers. The differential signal received on the LVDS input pins is first converted to CMOS logic levels. The signal is then transmitted across a silicon-dioxide (SiO2) based capacitive-isolation barrier using an on-off keying (OOK) modulation scheme. A high frequency carrier transmitted across the barrier represents one logic state and an absence of a carrier represents the other logic state. On the other side of the barrier a demodulator converts the OOK signal back to logic levels, which is then converted to LVDS outputs by a differential driver. These devices incorporate advanced circuit techniques to maximize CMTI performance and minimize radiated emissions.
The ISO782xLL family of devices is TIA/EIA-644-A standard compliant. The LVDS transmitters drive a minimum differential-output voltage magnitude of 250 mV into a 100-Ω load, and the LVDS receivers are capable of detecting differential signals ≥50 mV in magnitude. The device consumes 10 mA per channel at 100 Mbps with 5-V supplies.
The Functional Block Diagram section shows a conceptual block diagram of one channel of the ISO782xLL family of devices.
The ISO782xLL family of devices is available in two channel configurations with a default differential high-output state.
PART NUMBER | CHANNEL DIRECTION | RATED ISOLATION | MAXIMUM DATA RATE | DEFAULT DIFFERENTIAL OUTPUT |
---|---|---|---|---|
ISO7820LL | 2 Forward | 5700 VRMS / 8000 VPK (1) | 100 Mbps | High |
ISO7821LL | 1 Forward, 1 Reverse |
Table 1 lists the functional modes for the ISO782xLL family of devices.
VCCI | VCCO | INPUT (INx±)(2) |
OUTPUT ENABLE (ENx) |
OUTPUT (OUTx±)(3) |
COMMENTS |
---|---|---|---|---|---|
PU | PU | H | H or open | H | Normal Operation: A channel output assumes the logic state of the input. |
L | H or open | L | |||
I | H or open | H or L | |||
X | PU | X | L | Z | A low-logic state at the output enable causes the outputs to be in high impedance. |
PD | PU | X | H or open | H | Default mode: When VCCI is unpowered, a channel output assumes the logic high state. When VCCI transitions from unpowered to powered up, a channel output assumes the logic state of the input. When VCCI transitions from powered up to unpowered, a channel output assumes the selected default high state. |
X | PD | X | X | Undetermined | When VCCO is unpowered, a channel output is undetermined. When VCCO transitions from unpowered to powered-up, a channel output assumes the logic state of the input |