MIC2588_05 Datasheet, PDF (20/21 Pages) Micrel Semiconductor – Single-Channel, Negative High-Voltage Hot Swap Power Controllers

MIC2588/MIC2594
/PWRGD Signal Drive Capability
The /PWRGD signal can be used to drive an optoisolator or
an LED. 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 caused by common mode transients. Such
Micrel
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 10 shows how to con-
figure an optoisolator driven by the /PWRGD signal of the
MIC2588 controller.
R5
43kΩ
1
6
-48V RTN
-48V RTN
(Long Pin)
*D1
SMAT70A
100V
-48V RTN
(Short Pin)
R1
698kΩ
1%
R3
12.4kΩ
1%
C1
1uF
-48VIN
(Long Pin)
MOC207-M
2
5
R2
11.8 kΩ
1%
*C2
22nF
1 _/PWRGD
VDD ⁸
2 _OV
3 _UV
DRAIN ⁷
MIC2588-2BM
GATE ⁶
4 _VEE
SENSE ⁵
C5
100uF
C4
0.1uF
DC-DC
CONVERTER
IN+
OUT+
ON/OFF^#
IN-
OUT-
+2.5VOUT
+2.5V RTN
RFDBK
15kΩ
CFDBK
6.8nF
100V
VDD
*C6
0.33uF
RSENSE
0.01Ω
5%
R4
10Ω
C3
0.22uF
M1
SUM110N10-09
-48VOUT
Nominal Undervoltage and Overvoltage Thresholds:
VUV = 36.5V
VOV = 71.2V
* Optional components (See Applications Information for more details)
# An external pull-up resistor for the power-good signal is necessary for DC-DC supplies
(and all other load modules) not equipped with internal pull-up impedence
Figure 10. Optoisolator Driven by /PWRGD Signal
September 2005
20
M9999-083005