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PDF MAX5913A Data sheet ( Hoja de datos )
| Número de pieza | MAX5913A | |
| Descripción | +48V Quad Hot-Swap Controllers | |
| Fabricantes | Maxim Integrated Products | |
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19-3302; Rev 0; 5/04
+48V Quad Hot-Swap Controllers For
Power-Over-LAN
General Description
The MAX5913A/MAX5914A are quadruple hot-swap con-
trollers. The MAX5913A/MAX5914A independently con-
trol 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. The 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.
www.DTahteaSMheAeXt45U9.1c3oAm/MAX5914A feature an internal under-
voltage 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 MAX5913A features an
active-low relay driver that sinks current when the relay
output is enabled. The MAX5914A 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
MAX5913A/MAX5914A use an external sense resistor
to enable all the internal current-sense functions.
The MAX5913A/MAX5914A feature a programmable
analog 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 MAX5913A/MAX5914A 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
Midspan Power-Over-MDI
Features
♦ Wide Operating Input Voltage Range:
+35V to +72V
♦ IEEE 802.3af Compatible
♦ Four Independent Power Switch Controllers
♦ Open-Circuit Detector
♦ On-Board Charge Pumps to Drive External
n-Channel FETs
♦ Current Sense with External Resistor
♦ Foldback Current Limiting
♦ +32V Input Undervoltage Lockout
♦ On-Chip +12V, 100mA Voltage Relay Drivers
Ordering Information
PART
PIN-
TEMP RANGE PACKAGE
MAX5913AEMH -40°C to +85°C 44 MQFP
MAX5914AEMH* -40°C to +85°C 44 MQFP
*Future product—contact factory for availability.
PKG
CODE
M44-3
M44-3
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
MAX5913A
MAX5914A
33 RTRYEN
32 STATOUT
31 OCEN
30 DGND
29 VCC
28 CSP1
27 DRAIN1
26 GATE1
25 OUT1
24 CSP2
23 DRAIN2
Typical Operating Circuit 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 = 0V, RTIM = open, TA = +25°C, unless otherwise specified.)
TURN-ON INTO CAPACITIVE LOAD
(CL = 0.47µF)
MAX5913A/14A toc10
A
0
B
C
www.Da0taSheet4U.com
0
TURN-ON INTO CAPACITIVE LOAD
(CL = 47µF)
MAX5913A/14A toc11
A
0
B
C
0
0
TURN-ON INTO CAPACITIVE LOAD
(CL = 470µF)
MAX5913A/14A toc12
A
0
B
C
0
0
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)
MAX5913A/14A 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)
MAX5913A/14A 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)
MAX5913A/14A 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 MAX5913A/MAX5914A quadruple hot-swap con-
trollers provide Power-Over-MDI, also known as Power-
Over-LAN systems (Figure 5). The MAX5913A/
MAX5914A enable control of four external n-channel
MOSFET switches from a single VCC ranging from
+35V to +72V, with timing control and current-limiting
functions built in.
The MAX5913A/MAX5914A features include undervolt-
age lockout (UVLO), 100mA relay drivers, dual-level cur-
www.DreatnatShseeent4sUe.,cofomldback current limit, programmable
overcurrent time and auto-retry periods, internal charge
pumps to drive external MOSFET and soft-start, port sta-
tus output indicating power-OK (POK) or open-circuit
conditions (Figure 6).
Switch and Relay Control Inputs
The MAX5913A/MAX5914A 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_ simultaneously. The relay
is turned on while the switch is off so that there is no volt-
age 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 MAX5913A/MAX5914A operate from a +35V to +72V
supply voltage. VCC powers the MAX5913A/MAX5914A
analog circuitry and is monitored continuously during
startup and normal operation. The MAX5913A/MAX5914A
keep all MOSFET switches and relay drivers securely off
before VCC rises above VUVLO. The MAX5913A/
MAX5914A turn off all MOSFET switches and relay drivers
after VCC falls below VUVLO - VUVLO,H.
Startup
When the turn-on condition is met (see the Input
Voltage and UVLO and Switch and Relay Control Inputs
sections), the MAX5913A/MAX5914A slowly turn on the
external 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. 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 POK signal is asserted.
Current Sensing and Regulation
The MAX5913A/MAX5914A 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 | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet MAX5913A.PDF ] | |
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