MIC2587R-1BMTR [MICREL]
Power Supply Support Circuit, Fixed, 1 Channel, PDSO8, SOIC-8;
| 型号： | MIC2587R-1BMTR |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Power Supply Support Circuit, Fixed, 1 Channel, PDSO8, SOIC-8 光电二极管 |
| 文件： | 总7页 (文件大小：128K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2587 Evaluation Board
Single Channel, Positive-Voltage
Hot Swap Controller
allow for the use of high-current electrical cables to
transfer the necessary current through the power
MOSFET and to the load. See the Operation section for
details on how to select the values for these components
for desired system requirements. (Please refer to the
MIC2587 datasheet for detailed pin descriptions and
additional support information.)
General Description
MIC2587/MIC2587R Hot Swap Controller
The MIC2587 is a single-channel, positive-voltage hot-
swap controller designed to address the need for safe
insertion and removal of circuit boards into electrically
live system backplanes. With few external components,
the controller works in conjunction with an external N-
Channel MOSFET to provide inrush current limiting and
gate slew-rate control. Additionally, the current limit is
user-programmable and works in conjunction with a
user-programmable overcurrent timer to provide reliable
overcurrent fault protection to the system’s circuit
components. During an output overload condition, a
constant-current regulation loop is engaged to ensure
that the system power supply maintains regulation. As a
means to reduce the power consumption in the presence
of a severe overcurrent load, the MIC2587 is equipped
with a circuit that monitors the voltage level at the FB
pin, and once engaged, allows for the current limit to
“foldback” to a lower threshold to effectively reduce the
regulated current limit. Once the overcurrent timer
expires, the output of the MIC2587 is latched off and can
be reset by toggling the ON pin from high-to-low-to-high.
The MIC2587R will automatically restart the turn-on
cycle with a fixed duty cycle (≈ 5%) after the overcurrent
timer has expired. A master Power-Good signal is
provided to indicate that the output voltage of the soft-
start circuit is within its valid output range. The Power-
Good signal can be used to enable one or more
downstream DC-DC converter modules.
Basic Requirements
The MIC2587 controller requires a minimum of 10V for
operation, and the evaluation board is configured to
operate with 24V or 48V, depending upon the resistor
divider networks that are shown in a table inserted in the
circuit schematic.
Precautions
Unless the range of voltages over which the intended
application for the MIC2587/MIC2587R controller is well
controlled and carefully observed, the input and output
capacitors should have a maximum voltage rating of at
least 100V. Thus, the rating of these capacitors is at
minimum equivalent to the 100V transient maximum
voltage rating of the MIC2587 integrated circuits.
Note: The input capacitor should be an aluminum
electrolytic device, as most tantalum capacitors in this
voltage range are not capable of safely handling the
surge currents that will flow through CIN during a hot-plug
event. COUT, however, may be a tantalum capacitor as
the MIC2587 controls the di/dt and dv/dt seen by COUT
.
Ordering Information
MIC2587 Evaluation Board
Part Number
Description
The MIC2587 evaluation board is designed to showcase
the power switching capability of the MIC2587 controller.
The board is configured for switching 24V or 48V with a
nominal current limit of 4.7A. Several test points are
included for the user to monitor the response of a
number of pins (e.g. VIN, GATE, TIMER, and /PWRGD).
The Power-Good signal is an open-drain output, with
asserted status as either high impedance (-1) or active-
Low (-2). Additionally, banana plugs are provided to
MIC2587-1BM EV
Evaluation board with the
MIC2587-1BM device
MIC2587R-1BM EV
Evaluation board with the
MIC2587R-1BM device
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-102108-A
October 2008
Micrel, Inc.
MIC2587/MIC2587R Evaluation Board
Current Limit
Operation
The current-limit is determined using the following
formula:
External Switch
The MIC2587 requires an external N-Channel MOSFET
to serve as the power switch device. The MIC2587 pin
connections for the MOSFET terminals and sense
resistor are shown in the attached circuit schematic. The
SUM110N10-09, a power MOSFET in a TO-263
package from Vishay, is used as the pass device on the
evaluation boards. Several MOSFET devices suited for
use with the MIC2587 are listed in Table 3 at the end of
the datasheet.
ILIM = VTRIP / RSENSE
(1)
where VTRIP is the circuit breaker threshold obtained from
the Electrical Characteristics Table in the MIC2587
datasheet. For the MIC2587 evaluation board, the
nominal current limit ILIM = 47mV/10mΩ = 4.7A. Using
Equation 1 and some basic algebra, the value for RSENSE
can be determined given a desired current-limit by:
R
SENSE = VTRIP / ILIM
The circuit breaker is ‘tripped’ upon an overcurrent
condition that lasts longer than the time period tFLT
which is set by capacitor CTIMER (C7). If CTIMER = 0, tFLT
The ON control pin will switch the external MOSFET on
when the voltage at ON is greater than the specified
threshold voltage of 1.24V (typical). This pin exhibits
50mV of hysteresis. A three terminal jumper (J1) is used
to either pull-up the ON pin to VCC (through an external
resistive divider) or tie the pin-to-ground to disable the
controller.
,
=
tOCSENSE, the default value of 2µs. CTIMER may be
determined for a desired tFLT using the following
formula1.
C
TIMER = (ITIMERUP ∗ tFLT) / VTIMERH
(2)
where ITIMER, the typical current-limit timer current, is
65μA, and VTH, the typical timer threshold, is 1.313V.
Both values are found in the Electrical Characteristics
Table of the datasheet. Substituting these values into
Equation 2, the result is now approximated by:
Component Selection for Various VIN
Table 1 below displays the resistor values selected to
configure the MIC2587 controller with various input
voltages. The two resistor combinations are
implemented as resistive divider networks to attain
specific turn-on/turn-off and “Power-is-Good” thresholds.
These values are used for reference, but for different
threshold requirements, alternative resistor combinations
may be chosen that satisfy Equations 8 and 9 from the
MIC2587 datasheet.
CTIMER ≅ 50x10-6(A/V) ∗ tFLT
For a 6ms overcurrent delay, the calculated value for
C
TIMER is 0.3µF. The closest standard value is 0.33µF.
Programmable Output Slew Rate (CGATE
)
Capacitor CGATE is used to set the output slew rate and
limit the inrush current. An external GATE capacitor,
+16V
+24V
+32V
+48V
C
GATE, sets the GATE output rise-time (or slew rate) to
R1
95.3kΩ 49.9kΩ 261kΩ 287kΩ
10.0kΩ 3.40kΩ 12.4kΩ 10.0kΩ
35.7kΩ 59.0kΩ 93.1kΩ 143kΩ
3.57kΩ 3.57kΩ 4.22kΩ 4.22kΩ
turn on the external Power MOSFET. The source
(output) of the MOSFET then follows the GATE once the
GATE voltage exceeds the VG-S threshold. The rise time
is determined by the following equation:
R2
R5
R8
tRISE ≅ (ΔV ∗ CTOTAL) / IGATE
(3)
VIN(ON)
VIN(OFF)
VOUT(GOOD)
VOUT(NOT_GOOD)
13.8V
13.0V
14.4V
13.5V
20.6V
19.3V
23.0V
21.6V
29.0V
27.0V
30.3V
28.4V
39.0V
36.6V
45.8V
43.0V
where ΔV = VIN + 13V (13V typical enhancement for
MIC2587 GATE output for 10V ≤ VCC ≤ 80V) and IGATEON
is the nominal GATE pin pull-up current. The total
capacitance that the GATE must drive is the external
CGATE plus the parasitic capacitance, CG-S, of the
external MOSFET. For the SUM110N10-09, CG-S is
approximately 6.5nF. Given the following conditions:
Table1. Resistor Combinations for
Various System Voltage Levels
VIN = VOUT = 24V and CGATE = 47nF
tRISE ≅ (13V ∗ 53.5nF)/16µA ≅ 15ms.
R7 is used for stabilization of the current limit control
loop.
M9999-102108-A
October 2008
2
Micrel, Inc.
MIC2587/MIC2587R Evaluation Board
Circuit Schematic
TP1
VCC
+VCC
BJ1
VOUT
BJ2
R3
VCC
+VOUT
Q1
C4
0.1µF
C6
100µF
C3
C1
47µF
SUB85N10-10
C5
TP3
OUT
R1
287k
R2
10k
C2
0.1µF
0.1µF
JP1
ON
D2
MMBZ5248
0.1µF
R5
143k
D1
SMBG100A
R4
TP2
ON
R6
47.5k
U1
MIC2587/87R
TP10
FO
TP4
PWRGD
8
7
6
5
1
2
3
4
ON
VCC
SENSE
GATE
TP8
SENSE
FB
R8
4.22k
TP9
GATE
PWRD
GND
BJ3
TP7
CTIMER
CTIMER
C8
R7
1k
GND
C7
1µF
TP5
TP6
0.01µF
GND
GND
+48V +24V
R1
R2
R5
287k 49.9k
10k
3.4k
59k
143k
R8 4.22k 3.57k
Figure 1. MIC2587 EVB Circuit Schematic
M9999-102108-A
October 2008
3
Micrel, Inc.
MIC2587/MIC2587R Evaluation Board
Bill of Materials
Item
BJ1-BJ3
C1
Part Number
Manufacturer
Johnson(1)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
AVX(3)
Description
Qty.
3
108-0740-001
2222 038 59479
Banana Jack, 0.256" H/S
Electrolytic Capacitor, 47µF, 100V, 20%, Size 10x12
Ceramic Capacitor, 0.1µF, 100V, 20%, Y5V, Size 0805
Ceramic Capacitor, 330pF, 100V, 1%, COG, Size 0805
Electrolytic Capacitor, 100µF, 100V, 20%, Size 10X12
Ceramic Capacitor, 1µF, 100V, 20%, PET-HT, Size 4030
Ceramic Capacitor, 0.01µF, 100v, 20%, Y5V, Size 0805
Transzorb Diode, 100V
1
C2-C4
C5
VJ0805V104MXBCW1BC
VJ0805A331FXBAB
2222 0385 9101
3
1
C6
1
C7
CF162E0105J
1
C8
VJ0805V103MXBCW1BC
SMBG100A/2
Vishay(2)
Vishay(2)
Vishay(2)
Molex(4)
1
D1
1
D2
MMBZ5248B-GS08
22-03-2021
Zener Diode, 18V,5%
1
Jumper, 2-pin, 0.1” Center, 0.35” Hole
Jumper Shunt
1
J1
881545-2
Tyco(5)
1
MH1-MH4
534-2211
Keystone(6)
Keystone(6)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
Vishay(2)
Keystone(6)
Micrel(7)
Stand-off - 5/8", 6-32,Hex
4
MH1-MH4
5721-632-3/8
Machine Screws, 6-32 x 3/8
4
R1
R2
CRCW080549K9FKTA
CRCW08053K40FKTA
WSR2R0100FTA
CRCW080510R0FKTA
CRCW080559K0FKTA
CRCW080547K5FKTA
CRCW08051K002FKTA
CRCW08053K57FKTA
SUM110N10-09
Resistor, 49.9K, 1%, Size 0805
1
Resistor, 3.4K, 1%, Size 0805
1
R3
Resistor, 0.01Ω, 1%, 2w, Size 4527
Resistor, 10Ω, 1%, Size 0805
1
R4
1
R5
Resistor, 59k, 1%, Size 0805
1
R6
Resistor, 47.5k, 1%, Size 0805
1
R7
Resistor, 1k, 1%, Size 0805
1
R8
Resistor, 3.57k, 1%, Size 0805
1
Q1
N-Channel, 100V, MOSFET
1
TP1-TP10
U1
1593-2
Turret Terminal, 0.065" H/S
10
1
MIC2587-1BM or
MIC2587R-1BM
Single Channel, Positive-Voltage
Hot Swap Controller
Notes:
1. Johnson: www.tdk.com
2. Vishay: www.vishay.com
3. AVX: www.avx.com
4. Molex: www.molex.com
5. Tyco: www. tycoelectronics.com
6. Keystone: www.keyeleco.com
7. Micrel, Inc.: www.micrel.com
M9999-102108-A
October 2008
4
Micrel, Inc.
MIC2587/MIC2587R Evaluation Board
PCB Layout Recommendation
Top Assembly
Top Layer
M9999-102108-A
October 2008
5
Micrel, Inc.
MIC2587/MIC2587R Evaluation Board
PCB Layout Recommendation
Bottom Assembly
Bottom Layer
M9999-102108-A
October 2008
6
Micrel, Inc.
MIC2587/MIC2587R Evaluation Board
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2008 Micrel, Incorporated.
M9999-102108-A
October 2008
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