MIC2085/2086
Micrel
MIC2085/MIC2086
Single Channel Hot Swap Controllers
General Description
The MIC2085 and MIC2086 are single channel positive
voltage hot swap controllers designed to allow the safe
insertion of boards into live system backplanes. The MIC2085
and MIC2086 are available in 16-pin and 20-pin QSOP
packages, respectively. Using a few external components
and by controlling the gate drive of an external N-Channel
MOSFET device, the MIC2085/86 provide inrush current
limiting and output voltage slew rate control in harsh, critical
power supply environments. Additionally, a circuit breaker
function will latch the output MOSFET off if the current limit
threshold is exceeded for a programmed period of time. The
devices’ array of features provide a simplified yet robust
solution for many network applications in meeting the power
supply regulation requirements and affords protection of
critical downstream devices and components.
All support documentation can be found on Micrel’s web
site at www.micrel.com.
Features
• MIC2085: Pin for pin functional equivalent to the
LTC1642
• 2.3V to 16.5V supply voltage operation
• Surge voltage protection to 33V
• Operating temperature range –40°C to 85°C
• Active current regulation limits inrush current
independent of load capacitance
• Programmable inrush current limiting
• Analog foldback current limiting
• Electronic circuit breaker
• Dual-level overcurrent fault sensing
• Fast response to short circuit conditions (< 1µs)
• Programmable output undervoltage detection
• Undervoltage lockout protection
• Power-on reset (MIC2085/86) and
power-good (MIC2086) status outputs
• /FAULT status output
• Driver for SCR crowbar on overvoltage
Applications
• RAID systems
• Cellular base stations
• LAN servers
• WAN servers
• InfiniBand™ Systems
• Industrial high side switching
Typical Application
VIN
12V
/FAULT
GND
Backplane PCB Edge
Connector Connector
Long
Pin
Short
Pin
R5
47kΩ
R2
100kΩ
1%
Medium
(or Short)
Pin
R3
1.82kΩ
1%
R4
10kΩ
1%
C3
0.1µF
R1
3.3Ω
C1
1µF
RSENSE
0.007Ω
1 2% 2
3
4
Q1
Si7884DP
(PowerPAKTM SO-8)
*R6
10Ω
16
VCC
15
SENSE
GATE 14
4 ON
COMP+ 11
COMPOUT 10
6 /FAULT
MIC2085
9
OV
12 COMP—
5
/POR
FB 7
13 REF
1
CRWBR
CPOR
3
C4
0.1µF
GND CFILTER
8
2
C5
8200pF
C6
0.01µF
R7
127kΩ
1%
VLOGIC
CLOAD
220µF
VOUT
12V@5A
R10
47kΩ
R11
47kΩ
C2
0.022µF
Output Signal
(Power Good)
PWRGD
LOGIC
CONTROLLER
R8
16.2kΩ
1%
C7
0.033µF
Q2
2N4401
/RESET
Power-On Reset
Output
Q3
TCR22-4
**R9
180Ω
Long
Pin
Overvoltage (Input) = 13.3V
Undervoltage Lockout = 10.8V
Undervoltage (Output) &
Power-Good (Output) = 11.4V
POR/START-UP DELAY = 60ms
Circuit-Breaker Response Time = 500µs
*R6 is an optional component used for noise filtering
**R9 needed when using a sensitive gate SCR
InfiniBand is a trademark of InfiniBand Trade Association
PowerPAK is a trademark of Vishay Intertechnology Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
January 2004
1
M0235-121903