Overview
The LNBH21PD-TR, produced by STMicroelectronics, is a monolithic voltage regulator and interface IC specifically designed for analog and digital satellite STB receivers, SatTV sets, and PC cards. This IC provides a complete solution for LNB (Low Noise Blocker) power supply and control, featuring a step-up converter and an I²C interface. It is assembled in a PowerSO-20 package and is optimized for low component count, low power dissipation, and simple design.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| VCC DC Input Voltage | -0.3 to 16 | V |
| VUP DC Input Voltage | -0.3 to 25 | V |
| IO Output Current | Internally Limited | mA |
| VOTX/RX DC Output Pins Voltage | -0.3 to 25 | V |
| VI Logic Input Voltage (SDA, SCL, DSQIN, ISEL) | -0.3 to 7 | V |
| VDETIN Detector Input Signal Amplitude | -0.3 to 2 VPP | V |
| VOH Logic High Output Voltage (DSQOUT) | -0.3 to 7 | V |
| IGATE Gate Current | ± 400 mA | mA |
| VSENSE Current Sense Voltage | -0.3 to 1 | V |
| VADDRESS Address Pin Voltage | -0.3 to 7 | V |
| Tstg Storage Temperature Range | -40 to +150 | °C |
| Tj Operating Junction Temperature Range | -40 to +125 | °C |
| Rthj-case Thermal Resistance Junction-case | 2 | °C/W |
Key Features
- Built-in 22kHz tone oscillator compliant with DiSEqC 2.0 standards
- Step-up converter generating 13/18V power supply from a single input source (8V to 15V)
- I²C interface for control and diagnostics
- UnderVoltage Lockout (UVLO) circuit to disable the circuit when VCC drops below a fixed threshold (6.7V typ.)
- Overload and over-temperature internal protections
- LNB short circuit SOA (Safe Operating Area) protection with I²C diagnostic bits
- ±4kV ESD tolerant on input/output power pins
- Current limitation block with selectable current limit thresholds
- Analogic modulation input pin for external modulation
- Compliance with American LNB power supply standards up to 19.5V
Applications
The LNBH21PD-TR is designed for use in analog and digital satellite STB receivers, SatTV sets, and PC cards. It is particularly suited for:
- Satellite TV systems requiring DiSEqC 2.0 and DiSEqC 1.x compatibility
- Non-DiSEqC LNB remote control systems
- Systems needing precise 22kHz tone generation and detection
- Applications requiring low power dissipation and simple design
Q & A
- What is the primary function of the LNBH21PD-TR?
The primary function of the LNBH21PD-TR is to provide a 13/18V power supply and 22kHz tone signalling to LNB downconverters in satellite TV systems.
- What is the input voltage range for the VCC pin?
The input voltage range for the VCC pin is from -0.3V to 16V.
- How does the LNBH21PD-TR handle over-temperature conditions?
The LNBH21PD-TR has internal over-temperature protections that activate at a temperature threshold of 150°C with a hysteresis of 15°C.
- What is the purpose of the I²C interface in the LNBH21PD-TR?
The I²C interface is used for control and diagnostics, allowing the system to configure the IC and read diagnostic status.
- How does the LNBH21PD-TR handle short circuits in the LNB?
The LNBH21PD-TR has LNB short circuit SOA protection with I²C diagnostic bits to monitor and protect against short circuits.
- What is the significance of the 22kHz tone oscillator in the LNBH21PD-TR?
The 22kHz tone oscillator is factory-trimmed to comply with DiSEqC 2.0 standards and is used for tone signalling to the LNB.
- Can the LNBH21PD-TR be used in non-DiSEqC systems?
Yes, the LNBH21PD-TR can be used in non-DiSEqC systems by controlling the output voltage via the I²C interface.
- How does the LNBH21PD-TR compensate for voltage drops along the coaxial cable?
The LNBH21PD-TR has an LLC bit that can increase the selected voltage value to compensate for excess voltage drops along the coaxial cable.
- What is the thermal management requirement for the LNBH21PD-TR?
The LNBH21PD-TR requires a suitable heatsink to keep the junction temperature below the over-temperature protection threshold, with a recommended thermal resistance of less than 48°C/W.
- How does the LNBH21PD-TR handle external modulation signals?
The LNBH21PD-TR has an analogic modulation input pin (EXTM) that allows external modulation signals to be coupled to the IC using a DC blocking capacitor.
