Overview
The PM8908TR, produced by STMicroelectronics, is a high-efficiency monolithic step-down switching regulator. It is primarily designed for DDR memory termination applications, supporting DDR3, DDR4, and low-power DDR3/DDR4 memory types. The device operates from an input voltage range of 1 V to 3.5 V and features a constant frequency mode with two programmable switching frequencies of 0.6 MHz or 1 MHz. The PM8908TR integrates low RDS(on) N-channel MOSFETs for both high-side and low-side switches, ensuring high efficiency and fast switching transitions.
Key Specifications
| Parameter | Min. | Typ. | Max. | Unit |
|---|---|---|---|---|
| Input Voltage (VIN) | 1 | - | 3.5 | V |
| Supply Voltage (VCC) | 4.5 | 5.0 | 5.5 | V |
| Output Voltage (VOUT) | 0.5 | - | 2 | V |
| Switching Frequency | 600 kHz | - | 1 MHz | - |
| Output Voltage Accuracy | - | ±1% | - | - |
| Positive Overcurrent Threshold (IOCL) | 4 | 7.6 | 11 | A |
| Negative Overcurrent Threshold (IOCLN) | -11 | -7.6 | -4 | A |
| Thermal Resistance Junction to Ambient (RthJA) | - | 40 | - | °C/W |
| Maximum Junction Temperature (TMAX) | - | 150 | - | °C |
Key Features
- Integrated MOSFETs for high efficiency
- Current COT (Constant On-Time) architecture
- Constant frequency mode with two programmable switching frequencies (0.6 MHz or 1 MHz)
- ADJ output voltage from 0.5 V to 2 V with ±1% accuracy overtemperature variations
- Embedded bootstrap diode and external tracking support
- Overvoltage, undervoltage, overcurrent, and overtemperature protection
- Soft-off with integrated discharge resistor
- Power Good output for real-time voltage monitoring
- Compact QFN20 3.5 x 4.0 mm package
Applications
- Memory termination regulator for DDR3, DDR4, and low-power DDR3/DDR4
- Notebook, desktop, and server applications
- Low voltage applications for 1 V to 3.5 V input rails
Q & A
- What is the input voltage range of the PM8908TR?
The input voltage range is from 1 V to 3.5 V.
- What are the programmable switching frequencies of the PM8908TR?
The switching frequencies can be programmed to 0.6 MHz or 1 MHz.
- What is the output voltage accuracy of the PM8908TR?
The output voltage accuracy is better than ±1% over line, load, and temperature variations.
- Does the PM8908TR have built-in protection features?
- What is the purpose of the Power Good (PGOOD) output?
The PGOOD output provides real-time information about the output voltage status.
- How does the soft-off sequence work in the PM8908TR?
The soft-off sequence turns off both the high-side and low-side MOSFETs and connects an integrated discharge resistor between the PHASE and PGND pins.
- What is the thermal resistance junction to ambient (RthJA) of the PM8908TR?
The thermal resistance junction to ambient is 40 °C/W.
- What is the maximum junction temperature (TMAX) of the PM8908TR?
The maximum junction temperature is 150 °C.
- What type of package does the PM8908TR come in?
The PM8908TR is available in a QFN20 3.5 x 4.0 mm package.
- Does the PM8908TR support external tracking?
