MIC2589_05 Datasheet, PDF (27/29 Pages) Micrel Semiconductor – Single-Channel, Negative High-Voltage Hot Swap Power Controller/Sequencer

Micrel
Power-Good Signals Driving Optoisolators
The PWRGDx signals can be used to drive
optoisolators or LEDs. The use of an optoisolator is
sometimes needed to protect I/O signals (e.g.,
/PWRGD, RESET, ENABLE) of both the controller
and downstream DC-DC converter(s) from damage
MIC2589/MIC2595
caused by common mode transients. Such is the
case when an EMI filter is utilized to prevent DC-DC
converter switching noise from being injected back
onto the power supply. The circuit of Figure 11 shows
how to configure an optoisolator driven by the
/PWRGD signal of the MIC2589 controller.
R7
43k
R6
43k
R5
43k
1 ^OPTO#1 6
1 ^OPTO#2 6
1 ^OPTO#3 6
MOC207-M
2
5
MOC207-M
2
5
MOC207-M
2
5
-48V RTN
(Long Pin)
*D1
SMAT70A
-48V RTN
(Short Pin)
R1
689k
1%
R2
11.8k
1%
C_TIMER
0.068µF
MIC2589-2BM
1 _/PWRGD1
VDD ¹⁴
2 _{PGTIMER /PWRGD3} 13
3 _UV
/PWRGD2 ¹²
C4
100µF
C3
0.1µF
-48V RTN
(Long Pin)
C1
0.47µF
R3
12.4k
1%
C_FILTER
2.2µF
C_NLD
0.068µF
4 _OV
5 _CFILTER
6 _CNLD
7 _VEE
DRAIN ¹¹
GATE ¹⁰
SENSE ⁹
N/C ⁸
*C2
0.1µF
C6
100µF
C5
0.1µF
R4
10
C8
100µF
C7
0.1µF
R_SENSE
0.01
Nominal Undervoltage and Overvoltage Thresholds:
5%
V_UV = 36.5V
V_OV = 71.2V
*Optional components (See Funtional Description and Applications Information for more details)
M1
SUM110N10-09
#An external pull-up resistor for the power-good signal is necessary for DC-DC convertors (and all other load modules) not equipped with an
internal pull-up impedance
Figure 11. Optoisolators Driven by /PWRGD Signals
-48V RTN
IN+ OUT+
ON/OFF*
IN– OUT–
+5V_OUT
+5V RTN
IN+ OUT+
ON/OFF*
IN– OUT–
+2.5V_OUT
+2.5V RTN
IN+ OUT+
ON/OFF*
IN– OUT–
+1.8V_OUT
+1.8V RTN
December 2005
27
M9999-120505
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