
January 2004
1
M0235-121903
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.
Typical Application
GND
/FAULT
820C5
C4
0.1
μ
F
SENSE
VCC
ON
/FAULT
OV
CPOR
COMP
—
FB
/POR
COMPOUT
REF
GATE
COMP+
GND
CRWBR
CFILTER
C3
0.1
μ
F
Pin
Connector
Connector
Pin
Overvoltage (Input) = 13.3V
Undervoltage Lockout = 10.8V
Power-Good (Output) = 11.4V
Pin
(MPin
R1
C1
1
μ
F
R
0.007
2%
1
Q1
Si7884DP
(PowerPAK
TM
SO-8)
*R6
10
R3
1.82k
1%
R8
R2
100k
1%
R5
47k
R4
10k
1%
MIC2085
C2
μ
F
C6
0.01
μ
F
C7
μ
F
C
LOAD
220
μ
F
R7
PWRGD
/RESET
Power-On Reset
Output
Output Signal
(Power Good)
**R9
Q3
Q2
V
12V@5A
V
IN
12V
LOGIC
CONTROLLER
1
2
8
3
16
15
7
5
10
13
12
9
6
4
11
14
2
3
4
POR/START-UP DELAY = 60ms
μ
s
Circuit-Breaker Response Time = 500
**R9 needed when using a sensitive gate SCR
R11
R10
47k
V
LOGIC
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 (< 1
μ
s)
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
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
InfiniBand is a trademark of InfiniBand Trade Association
PowerPAK is a trademark of Vishay Intertechnology Inc.