Overview
The LM25069PMM-2/NOPB, produced by Texas Instruments, is a positive low voltage power limiting hot swap controller designed to manage the insertion and removal of circuit cards from live power sources. This controller ensures safe and controlled power-up and power-down sequences, preventing voltage sag and minimizing the impact on other circuits in the system. It features an internal high side charge pump and gate driver for an external N-channel MOSFET, providing intelligent control over the power supply voltage during these transitions.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Operating Voltage Range | +2.9V to +17V | V |
| Transient Capability | Up to 20V | V |
| Under-Voltage Lockout (UVLO) Threshold | 1.17V | V |
| Over-Voltage Lockout (OVLO) Threshold | 1.16V | V |
| Current Limit | Programmable | A |
| Power Limit | Programmable | W |
| Power Good (PGD) Output Threshold | Within 1.3V of input voltage | V |
| Package Type | 10-pin VSSOP |
Key Features
- In-rush current limiting to prevent system voltage droop and transients during circuit card insertion.
- Programmable maximum power dissipation in the external series pass N-channel MOSFET to ensure operation within the Safe Operating Area (SOA).
- Adjustable under-voltage lockout (UVLO) and over-voltage lockout (OVLO) with hysteresis.
- Initial insertion timer to allow ringing and transients to subside after system connection.
- Programmable fault timer to avoid nuisance trips.
- Active high open drain POWER GOOD output indicating when the output voltage is within 1.3V of the input voltage.
- Circuit breaker function for severe over-current conditions.
- Available in latched fault and automatic restart versions (LM25069-1 and LM25069-2).
Applications
- Server backplane systems.
- Base station power distribution systems.
- Solid state circuit breakers.
- Hot swap applications in live power sources.
Q & A
- What is the operating voltage range of the LM25069?
The LM25069 operates within a voltage range of +2.9V to +17V, with a transient capability up to 20V.
- How does the LM25069 manage in-rush current during circuit card insertion?
The LM25069 limits in-rush current through programmable current limiting and power limiting circuits, preventing system voltage droop and transients.
- What is the purpose of the POWER GOOD (PGD) output?
The POWER GOOD output indicates when the output voltage is within 1.3V of the input voltage, signifying stable operation.
- Can the LM25069 be used in circuit breaker applications?
- How do the LM25069-1 and LM25069-2 versions differ?
The LM25069-1 latches off after a fault detection and requires external re-enable, while the LM25069-2 automatically restarts with a defined timing cycle.
- What is the role of the under-voltage lockout (UVLO) and over-voltage lockout (OVLO) in the LM25069?
The UVLO and OVLO circuits enable the LM25069 when the system input voltage is within the desired thresholds, preventing operation outside these limits.
- How is the fault timer configured in the LM25069?
The fault timer is configured using an external capacitor connected to the TIMER pin, which sets the insertion time delay and the fault timeout period.
- What package type is the LM25069 available in?
The LM25069 is available in a 10-pin VSSOP package.
- Can the LM25069 be used in hot swap applications?
- How does the power limiting function work in the LM25069?
The power limiting function monitors the drain-source voltage and drain current of the MOSFET, modulating the gate voltage to regulate the current and keep the power dissipation within the programmed threshold.
