LM25066A
July 11, 2011
System Power Management and Protection IC with
PMBus
General Description
The LM25066A combines a high performance hot-swap con-
troller with a PMBus compliant SMBus/I2C interface to ac-
curately measure, protect and control the electrical operating
conditions of computing and storage blades connected to a
backplane power bus. The LM25066A continuously supplies
real-time power, voltage, current, temperature and fault data
to the system management host via the SMBus interface.
The LM25066A control block includes a unique hot-swap ar-
chitecture that provides current and power limiting to protect
sensitive circuitry during insertion of boards into a live system
backplane, or any other "hot" power source. A fast acting cir-
cuit breaker prevents damage in the event of a short circuit
on the output. The input under-voltage and over-voltage lev-
els and hysteresis are configurable, as well as the insertion
delay time and fault detection time. A temperature monitoring
block on the LM25066A interfaces with a low-cost external
diode for monitoring the temperature of the external MOSFET
or other thermally sensitive components. The POWER GOOD
output provides a fast indicator when the input and/or output
voltages are outside their programmed range. LM25066A
current measurement accuracy is ±1% over temperature.
The LM25066A monitoring block computes both the real-time
and average values of subsystem operating parameters
(V
IN, IIN, PIN, VOUT) as well as the peak power. Accurate power
averaging is accomplished by averaging the product of the
input voltage and current. A black box (Telemetry/Fault Snap-
shot) function captures and stores telemetry data and device
status in the event of a warning or a fault.
Features
■ Input voltage range: 2.9V to 17V
■ I2C/SMBus interface and PMBus compliant command
structure
■ Programmable 25mV or 46mV current limit threshold
■ Configurable circuit breaker protection for hard shorts
■ Configurable under-voltage and over-voltage lockouts
with hysteresis
■ Remote temperature sensing with programmable warning
and shutdown thresholds
■ Detection and notification of damaged MOSFET condition
■ Real time monitoring of V
IN, VOUT, IIN, PIN, VAUX with 12-bit
resolution and 1 kHz sampling rate
■ Current measurement accuracy: ±1% over temperature
■ Power measurement accuracy: ±2% over temperature
■ True input power measurement using simultaneous
sampling of V
IN and IIN accurately averages dynamic
power readings
■ Averaging of V
IN, IIN, PIN, and VOUT over programmable
interval ranging from 0.001 to 4 seconds
■ Programmable WARN and FAULT thresholds with
SMBA notification
■ Black box capture of telemetry measurements and device
status triggered by WARN or FAULT condition
■ 24-lead LLP package
Applications
■ Server backplane systems
■ Basestation power distribution systems
■ Solid state circuit breaker
Typical Application Schematic
30146011
2011 National Semiconductor Corporation
301460
www.national.com
LM25066A
System
Power
Management
and
Protection
IC
with
PMBus