MAX5920 Maxim, MAX5920 Datasheet - Page 12

• Manufacturer Part Number: MAX5920
• Description: -48V Hot-Swap Controller with External RSENSE
• Manufacturer: Maxim

-48V Hot-Swap Controller
with External R
Figure 10. Automatic Restart After Current Fault
Figure 11. Undervoltage and Overvoltage Sensing
12
-48V RTN
-48V
*DIODES INC. SMAT70A.
______________________________________________________________________________________
V
V
*
UV
OV
= 1.255
= 1.255
1N4148
D1
2N2222
Q2
-48V RTN
R4 + R5 + R6
R4 + R5 + R6
(SHORT PIN)
R5 + R6
510kΩ
100V
-48V
1MΩ
1µF
-48V RTN
R6
C4
5%
5%
R8
R7
(SHORT PIN)
-48V RTN
R4
R5
R6
ZVN3310
NODE1
Q3
549kΩ
10kΩ
1%
1%
R6
R6
3
2
P
UV
OV
6.49kΩ
549kΩ
MAX5920A
MAX5920B
1%
1%
R4
R5
V
V
SENSE
DD
EE
8
4
UV
OV
V
EE
0.02Ω
5%
R1
SENSE
MAX5920A
C1
470nF
25V
V
DD
IRF530
GATE
Figure 11 shows how to program the undervoltage and
overvoltage trip thresholds using three resistors. With R4
= 549kΩ, R5 = 6.49kΩ, and R6 = 10kΩ, the undervoltage
threshold is set to 38.5V (with a 43V release from under-
voltage), and the overvoltage is set to 71V. The resistor-
divider also increases the hysteresis and overvoltage
lockout to 4.5V and 2.8V at the input supply, respectively.
The PWRGD (PWRGD) output can be used directly to
enable a power module after hot insertion. The
MAX5920A (PWRGD) can be used to enable modules
with an active-low enable input (Figure 13), while the
MAX5920B (PWRGD) is used to enable modules with
an active-high enable input (Figure 12).
The PWRGD signal is referenced to the DRAIN termi-
nal, which is the negative supply of the power module.
The PWRGD signal is referenced to V
When the DRAIN voltage of the MAX5920A is high with
respect to V
pulldown MOSFET Q2 is off and the PWRGD pin is in a
high-impedance state (Figure 13). The PWRGD pin is
Q1
N
R2
10Ω
5%
1kΩ
5%
R3
3.3nF
100V
C2
PWRGD
DRAIN
EE
or the GATE voltage is low, the internal
C3
100µF
100V
PWRGD /PWRGD Output
1s/div
EE
.
NODE1
50V/div
GATE
2V/div