Overview
The UCC3750N, produced by Texas Instruments, is a Source Ringer Controller integrated circuit designed to provide complete control and protection functions for a four-quadrant flyback converter. This IC is specifically used to generate ring signals for telephone circuits. It controls a primary side switch and two secondary switches, which act as synchronous rectifier switches during positive power flow. The UCC3750N also includes an onboard sine wave reference with programmable frequencies of 20Hz, 25Hz, and 50Hz, making it versatile for different phone systems.
Key Specifications
| Parameter | Min | Typ | Max | Units |
|---|---|---|---|---|
| Input Supply Voltage (VDD) | - | - | 7.5 | V |
| Maximum Forced Voltage (VCP) | -0.3 | - | 13.2 | V |
| Supply Current - Active | 0.5 | 1 | - | mA |
| Internal Reference Output Voltage (REF) | 7.3 | 7.55 | 7.8 | V |
| Load Regulation (IREF = 0mA – 2mA) | 30 | 60 | - | mV |
| Line Regulation (VCP = 10V to 13V, IREF = 1mA) | 3 | 15 | - | mV |
| Sine Reference Accuracy (TJ = 25°C) | -1 | 0 | 1 | Hz |
| Total Harmonic Distortion (THD) | - | 2 | - | % |
Key Features
- Provides control for flyback-based four-quadrant amplifier topology
- Onboard sine wave reference with low THD
- Selectable ringing frequency for different phone systems (20Hz, 25Hz, and 50Hz)
- Programmable output amplitude and DC offset
- DC current limiting for short circuit protection
- Secondary side voltage mode control
- Operates from a single 5V supply
- Internal 3V and 7.5V references
- Triangular clock oscillator and buffer amplifier for programmable DC offset
- Uncommitted amplifier for other signal processing requirements
- Charge-pump circuit for gate drive voltage
Applications
The UCC3750N is primarily used in telephone systems to generate ring signals. It is suitable for any application requiring a four-quadrant flyback converter, such as:
- Telephone ring generators
- Bi-directional power transfer systems
- Isolated power supplies requiring synchronous rectification
- Systems needing programmable output amplitude and DC offset
Q & A
- What is the primary function of the UCC3750N?
The UCC3750N is a Source Ringer Controller that provides complete control and protection functions for a four-quadrant flyback converter, primarily used to generate ring signals for telephone circuits.
- What are the programmable frequencies of the UCC3750N?
The UCC3750N has programmable frequencies of 20Hz, 25Hz, and 50Hz.
- How does the UCC3750N handle power transfer?
The UCC3750N controls a primary side switch and two secondary switches, which act as synchronous rectifier switches during positive power flow, allowing for bi-directional power transfer.
- What is the input supply voltage range for the UCC3750N?
The input supply voltage (VDD) should not exceed 7.5V.
- Does the UCC3750N have built-in protection features?
Yes, the UCC3750N includes DC current limiting for short circuit protection.
- How does the UCC3750N generate its reference signal?
The UCC3750N uses an onboard sine wave reference derived from a high-frequency (32kHz) crystal connected externally.
- What is the role of the charge-pump circuit in the UCC3750N?
The charge-pump circuit generates the gate drive voltage necessary for the operation of the switches in the converter.
- Can the UCC3750N operate with external sine waves?
Yes, the ring generator can also be used at other frequencies by supplying externally generated sine-waves to the chip.
- What is the typical operating current of the UCC3750N?
The UCC3750N typically requires about 5mA to operate without any loads on the drive outputs.
- What are some common applications of the UCC3750N?
The UCC3750N is used in telephone ring generators, bi-directional power transfer systems, and isolated power supplies requiring synchronous rectification.
