powerZONE Products for the week of April 8, 2002
Micrel Says . . .
MIC2590A: Hot-Swap Power Controller Targets High-Reliability
PCI Applications
Compliant to the latest PCI Hot-Plug version 1.1 standard.
Adds SMBus support with integrated ADC for sophisticated power management
and diagnostics.
A new hot-swap power controller IC supporting the latest PCI hot-plug standards
is now available from Micrel Semiconductor, an industry leader in power
management and high speed communications integrated circuits.
Manufactured in a 48-pin TQFP package, the MIC2590 is a dual-slot power controller that supports all system voltages required by PCI, including the 3.3V auxiliary voltage specified by PCI Standard Version 2.2. The device supports +12V, -12V, 3.3V, 5.0V primary supplies, and 3.3V auxiliary supplies with overcurrent protection. The MIC2590 offers adjustable overcurrent timeout, circuit-breaker fault protection, undervoltage lockout, output voltage monitoring and output voltage slew rate control.
The MIC2590 also regulates the output current to ensure that inrush current never exceeds the programmed threshold. This feature improves the performance of a system with highly capacitive loads associated with many PCI adapter cards.
System reliability and performance monitoring is increased by an integrated 8-bit analog-to-digital converter (ADC) that provides the system designer with the means to monitor the voltage and current of any supply in any PCI slot. In addition, the specific cause of a fault in any supply is recorded in internal registers accessible via the SMBus interface. This feature provides the system designer with comprehensive diagnostics and power management capabilities supported by the Intelligent Peripheral Management Interface (IPMI) standard.
"System reliability is key in network servers, so the MIC2590 was
designed to address PCI power distribution applications with the additional
flexibility and enhanced performance demanded by network system designers,"
said Larry Mazer, business unit manager for hot-swap products.
analogZONE Says . . .
The MIC2590A is a cost-effective PCI hot-swap controller for PCI, compliant with versions 1.1 and 2.2. It limits the inrush currents to the load of the PCI card and controls the turn-on rate of the circuits. It also provides input and output supervisory control of input and output voltages as well as current limiting. It has two discrete channels -- with thermal protection between them -- so that two PCI cards can be protected. As per PCI specification 2.2, +5 V, +3.3 V, +12 V, -12 V, and +3.3 V (Aux) supplies are supported. The fast-trip thresholds for +12 V and -12 V (1.5 A/0.4 A) are common for all parts but four different versions support fast-trip thresholds for 5 V and 3.3 V at 113 mV, 150 mV, and 200 mV (nominals) with the fourth part having such fast-trip disabled. The parts integrate 12 V, -12 V, and -3.3 V auxiliary MOSFETs.
The quiescent currents depend on how many outputs are being used but the maximum for any one operating output is about 1.2 mA. The standby current is a typical 2.5 mA, and under-voltage lockout hysteresis is provided on both the standby rail and the input voltage lines. When a slot is powered down internal switches are connected to each of the outputs to discharge any of the circuit board's bypass capacitors.
The MIC2590A has an on-board 20-channel 8-bit ADC to monitor the output voltage and current of each supply. Apart from control, this information is available at the system management interface. Either the system management interface or the hot-plug interface may be used for control, but not both. Kelvin sensing needs to be employed for the external sense resistors required and care must be taken in the choice of external MOSFETs for voltage breakdown, on-state resistance, and for both steady-state and transient thermal issues. A Scotty diode is also recommended to clamp the -12 V input (which will be the substrate voltage) to avoid any damage from ringing or transients when that input starts to discharge towards ground.
The MIC2590A will be way at the top of the stack of products to look at for PCI hot-swap management and although there are other dual-channel products I don't believe any of the others are compliant to PCI 2.2.
The MIC2590A is in production in a TQFP-48 and is priced at $8.20 in
1000-piece lots.