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PDF MAX5914EMH Data sheet ( Hoja de datos )
| Número de pieza | MAX5914EMH | |
| Descripción | +48V Quad Hot-Swap Controllers For Power-Over-LAN | |
| Fabricantes | Maxim Integrated | |
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19-2244; Rev 2; 11/02
+48V Quad Hot-Swap Controllers For
Power-Over-LAN
General Description
The MAX5913/MAX5914 are quadruple hot-swap con-
trollers. The MAX5913/MAX5914 independently control
four external N-channel switches to hot-swap system
loads from a single VCC supply line. The devices allow
the safe insertion and removal of power devices from
live network ports. Operating supply voltage range is
between +35V and +72V. The devices are intended for
applications in Power-Over-Media-Dependent Interface
(MDI), but are not limited to such usage.
The MAX5913/MAX5914 feature an internal undervolt-
age lockout (UVLO) function that prevents the FET from
turning on, if VCC does not exceed the default value of
+32V. The devices also feature a +12V relay driver with
100mA current drive capable of driving low-voltage
+3.3V relays. The MAX5913 features an active-low relay
driver that sinks current when the relay output is
enabled. The MAX5914 features an active-high relay
driver output that sources 1mA to drive an external FET
relay driver when the relay output is enabled. Control
circuitry ensures the relays and the FETs are off until
VCC reaches the UVLO threshold. The MAX5913/
MAX5914 use an external sense resistor to enable all
the internal current-sense functions.
The MAX5913/MAX5914 feature a programmable ana-
log current-limit circuit. If the switch remains in current
limit for more than a programmable time, the N-channel
FET latches off and the supply can be restarted either
by autoretry or by an external command after the preset
off-time has elapsed.
The MAX5913/MAX5914 are available in a 44-pin MQFP
package and are specified for the extended -40°C to
+85°C operating temperature range.
Applications
Power-Over-LAN
Power-Over-MDI
IP Phone Switches/Routers
Telecom Line Cards
Network Switches/Routers
Mid-Span Power-Over-MDI
Features
o Wide Operating Input Voltage Range
+35V to +72V
o IEEE 802.3AF Compatible
o Four Independent Power Switch Controllers
o Open-Circuit Detector
o On-Board Charge Pumps to Drive External
N-Channel FETs
o Current Sense with External Resistor
o Foldback Current Limiting
o +32V Input Undervoltage Lockout
o On-Chip +12V, 100mA Voltage Relay Drivers
PART
MAX5913EMH
MAX5914EMH
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
44 MQFP
44 MQFP
TOP VIEW
Pin Configuration
FAULT
STAT1
STAT2
STAT3
STAT4
CSP4
DRAIN4
OUT4
GATE4
CSP3
DRAIN3
1
2
3
4
5
6
7
8
9
10
11
MAX5913
MAX5914
33 RTRYEN
32 STATOUT
31 OCEN
30 DGND
29 VCC
28 CSP1
27 DRAIN1
26 GATE1
25 OUT1
24 CSP2
23 DRAIN2
Typical Operating Circiut appears at end of data sheet.
MQFP
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
+48V Quad Hot-Swap Controllers For
Power-Over-LAN
Typical Operating Characteristics (continued)
(VCSP_ = VCC = +48V, VDD = +3.3V, VRLY = +12V, AGND = DGND = 0, RTIM = open, TA = +25°C, unless otherwise specified.)
TURN-ON INTO CAPACITIVE LOAD
(CL = 0.47µF)
MAX5913/4 toc10
A
0
B
C
TURN-ON INTO CAPACITIVE LOAD
(CL = 47µF)
MAX5913/4 toc11
A
0B
C
TURN-ON INTO CAPACITIVE LOAD
(CL = 470µF)
MAX5913/4 toc12
A
0
B
C
0 00
0 00
0
400µs/div
RLYON = VDD
A: VON, 5V/div
B: VGATE, 20V/div
C: VOUT, 20V/div
D: IOUT, 100mA/div
D
CURRENT-LIMIT FOLDBACK
(VCC = +36V)
MAX5913/4 toc13
A
0B
0
1ms/div
RLYON = VDD, RRTIM = 2kΩ
A: VON, 5V/div
B: VGATE, 20V/div
C: VOUT, 20V/div
D: IOUT, 200mA/div
D
CURRENT-LIMIT FOLDBACK
(VCC = +48V)
MAX5913/4 toc14
A
0B
0
10ms/div
RLYON = VDD, RRTIM = 40kΩ
A: VON, 5V/div
B: VGATE, 20V/div
C: VOUT, 20V/div
D: IOUT, 200mA/div
D
CURRENT-LIMIT FOLDBACK
(VCC = +57V)
MAX5913/4 toc15
A
0
B
0
C
0
10ms/div
RLYON = VDD, RL = 100Ω, RRTIM = 40kΩ, CLOAD = 470µF
A: VON, 5V/div
B: VOUT, 10V/div
C: IOUT, 200mA/div
0C
0
10ms/div
RLYON = VDD, RL = 139Ω, RRTIM = 40kΩ, CLOAD = 470µF
A: VON, 5V/div
B: VOUT, 10V/div
C: IOUT, 200mA/div
0C
0
10ms/div
RLYON = VDD, RL = 162Ω, RRTIM = 40kΩ, CLOAD = 470µF
A: VON, 5V/div
B: VOUT, 10V/div
C: IOUT, 200mA/div
_______________________________________________________________________________________ 5
5 Page 
+48V Quad Hot-Swap Controllers For
Power-Over-LAN
Detailed Description
The MAX5913/MAX5914 quadruple hot-swap controllers
provide Power-Over-MDI, also known as Power-Over-
LAN systems (Figure 5). The MAX5913/MAX5914 enable
control of four external N-channel MOSFET switches
from a single VCC ranging from +35V to +72V, with tim-
ing control and current-limiting functions built in.
Features include undervoltage lockout (UVLO), 100mA
relay drivers, dual-level current sense, foldback current
limit, programmable overcurrent time and auto-retry
periods, internal charge pumps to drive external MOS-
FET and soft-start, port status output indicating Power-
OK or open-circuit conditions (Figure 6).
Switch and Relay Control Inputs
The MAX5913/MAX5914 ON_ inputs turn on the corre-
sponding MOSFET switch. Driving ON_ high turns on
the switch if the corresponding RLYON is driven high,
and VCC > VUVLO for more than 25.6ms. Driving
RLYON_ high immediately turns on the corresponding
relay, and activates the 25.6ms delay after which the
corresponding ON_ input is active. Driving RLYON_ low
immediately turns off the switch and activates a 3.2ms
delay after which the relay is turned off. These internal
delays safely allow driving ON_ and RLYON_ simulta-
neously. The relay is turned on while the switch is off so
that there is no voltage across the relay contacts. The
relay is turned off while the switch is off so that there is
no current flowing when the relay contacts are opened
(see Figure 3).
Input Voltage and UVLO
The MAX5913/MAX5914 operate from +35V to +72V
supply voltage. VCC powers the MAX5913/MAX5914
analog circuitry and is monitored continuously during
startup and normal operation. The MAX5913/MAX5914
keep all MOSFET switches and relay drivers securely
off before VCC rises above VUVLO. The MAX5913/
MAX5914 turn off all MOSFET switches and relay dri-
vers after VCC falls below VUVLO - VUVLO,H.
Startup
When the turn-on condition is met (see Input Voltage
and UVLO and Switch and Relay Control Inputs sec-
tions), the MAX5913/MAX5914 slowly turn on the exter-
nal MOSFET switch by charging its gate using a
constant current source, IGATE (10µA typ). The gate
voltage slope is determined by the total gate capaci-
tance CGATE connected to this node. Since the output
voltage follows the gate voltage, thus the output rises
with a slope determined by:
∆VOUT = IGATE
∆t CGATE
If a capacitor load is connected to the output the total
current through the FET is:
I = IGATE
CL
CGATE
+ IL
where CL is the load capacitance and IL is the current
required by any load connected to the output during
the startup phase.
If the current through the FET reaches the programmed
current-limit value:
IMAX = VSC
RSENSE
the internal current-limit circuitry activates and regu-
lates this FET current to be a value, ILIM, that depends
on VOUT (IFLBK) (Figure 8). See the Current Sensing
and Regulation section for more information. In this
case the maximum rate of change of the output is
determined by:
∆VOUT = ILIM − IL
∆t CL
The formula shows the necessity for ILIM to be larger
than IL in order to allow the output voltage to rise. The
foldback function is active as long as the circuit is in
overcurrent condition. Should the overcurrent condition
persist for a period longer than the maximum time tO,
the switch is latched off and GATE_ is discharged to
ground with a 1mA pulldown current.
If auto-retry is enabled, the switch turns on again after a
waiting period, tOFF, which is determined by the pro-
grammed duty cycle.
After the startup, the internal charge pumps provide
(VCC + 9V) typical gate overdrive to fully turn on the
switch. When the switch is fully on (voltage drop across
the switch is ≤ 1.5V), and the switch is not in current
limit, the Power-OK signal is asserted.
Current Sensing and Regulation
The MAX5913/MAX5914 control port current with using
two voltage comparators (dual-level detection) that
sense the voltage drop across an external current-
sense resistor. Connect CSP_ to VCC and connect a
current-sense resistor between CSP_ and DRAIN_.
Kelvin sensing should be used as shown in Figure 7.
______________________________________________________________________________________ 11
11 Page | ||
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