View MAX5911_173051.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-1832; Rev 0a; 1/01
-48V Simple Swapper Hot-Swap Switches
General Description
The MAX5911/MAX5912 are fully integrated hot-swap switches for negative supply rails. These devices allow the safe insertion and removal of circuit cards into live backplanes or ports without causing problematic glitches on the negative power-supply rail. They also monitor various circuit parameters and disconnect the load if a fault condition occurs, alerting the host with a logic-level FAULT output. The MAX5911/MAX5912 operate over a voltage range of -16V to -65V and are designed to permit hot plugging of an IP phone into a hub, but are not limited to that operation. During startup, an internal power FET regulates the current between the backplane power source and the load to 280mA for MAX5911 and 415mA for MAX5912. After startup, the FET is fully enhanced to reduce its on-resistance. To ensure robust operation, the MAX5911/ MAX5912 contain built-in safety features that prevent damage to the internal FET. They include an enable input, which responds to positive logic signals (+3.3V or +5V), allowing the host system to disconnect the load. ENABLE is also used to reset the device after a latching fault condition occurs. The MAX5911/MAX5912 Simple SwapperTM hot-swap ICs monitor four parameters for these fault conditions: undervoltage lockout (UVLO), power-not-good, zerocurrent detection, and thermal shutdown. These devices are available in the extended temperature range, -40C to +85C. The MAX5911 and MAX5912 come in 8-pin and 16-pin SOIC packages, respectively.
Features
o Provides Safe Hot Swap for -16V to -65V Power Supplies o 280mA Current Limit for MAX5911 o 415mA Current Limit for MAX5912 o Zero-Current Load Disconnect o Integrated Power FET o Status Output Reports Fault Condition o Internal Switch-Protection Circuitry o Built-In Thermal Shutdown o DGND Can Vary Up to 5V with Respect to AGND
MAX5911/MAX5912
Ordering Information
PART MAX5911ESA MAX5912ESE TEMP. RANGE -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 16 SO
Simple Swapper is a trademark of Maxim Integrated Products, Inc.
Pin Configurations
TOP VIEW
GATE 1 VIN 2 8 7 UVLO VOUT AGND ENABLE
Applications
IP Phones Network Routers Network Switches Internet Appliances Power-Over-LAN
FAULT
3
MAX5911
6 5
DGND 4
8 SO
Typical Operating Circuit
VIN (-48V) +3.3V 0.1F VIN MAX5911 MAX5912 UVLO FAULT POSITIVE LOGIC LOAD VOUT
N.C.* N.C.* GATE VIN VIN FAULT DGND
1 2 3 4 5 6 7 8
16 N.C.* 15 UVLO 14 VOUT 13 V IN
MAX5912
12 VIN 11 AGND 10 ENABLE 9 N.C.*
3.3k
ENABLE DGND AGND
N.C.*
16 SO
AGND DGND
*THESE PINS ARE NOT INTERNALLY CONNECTED.
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
-48V Simple Swapper Hot-Swap Switches MAX5911/MAX5912
ABSOLUTE MAXIMUM RATINGS
Voltages are with respect to AGND, unless otherwise noted. VIN ..........................................................................+0.3V to -70V VOUT ............................................................+0.3V to (VIN - 0.3V) ENABLE to DGND ..................................................-0.3V to +11V ENABLE to VIN .......................................................-0.3V to +70V FAULT to DGND .....................................................-0.3V to +11V UVLO to VIN ............................................................-0.3V to +11V DGND ..........................................................................-5V to +5V DGND to VIN ...........................................................-0.3V to +70V FAULT Sink Current ............................................................10mA Continuous Output Current ...............................Internally Limited Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.9mW/C above +70C)..................470mW 16-Pin SO (derate 12.9mW/C above +70C)...........1039mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-60C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL SPECIFICATIONS
(VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, and TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Input Voltage Range Supply Current Maximum VOUT Current DMOS On-Resistance VOUT Leakage Current ENABLE Low Voltage ENABLE High Voltage ENABLE High Input Current ENABLE Low Pulse Width (Note 1) FAULT Output Low Voltage FAULT Output Leakage Current Zero-Current Detection Threshold Zero-Current Detection Threshold Hysteresis Zero-Current Detection Delay (Note 2) Current-Limit Delay (Note 3) Power-Good Threshold Power-Good Hysteresis VIL VIH IIH tEPW VOL IOH IFTH IFHY IFDEL tLIMIT VPG PGHYS VOUT shorted to AGND |VIN - VOUT|, |VIN - VOUT| decreasing % of VPG 1.95 280 I FAULT = 3mA V FAULT = +3.3V Decreasing load current -12 -8 1.5 350 10 2.15 5 520 20 2.35 SYMBOL VIN IIN IOUT(MAX) RDS(ON) Measured at AGND at the end of output voltage slew VOUT = VIN + 5V MAX5911 IOUT = -225mA, MAX5912 IOUT = -350mA Measured on VOUT when internal DMOS is shut off Referenced to DGND Referenced to DGND VENABLE = +3.3V 200 0.4 10 -4 2.0 140 300 MAX5911 MAX5912 -310 -457 CONDITIONS MIN -65 1.5 -280 -415 2.5 TYP MAX -16 2.5 -250 -373 4 10 0.8 UNITS V mA mA A V V A ns V A mA mA ms s V %
2
_______________________________________________________________________________________
-48V Simple Swapper Hot-Swap Switches
ELECTRICAL SPECIFICATIONS (continued)
(VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, and TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Power-Not-Good Output Delay (Note 4) Thermal Shutdown Temperature (Note 5) Default UVLO UVLO Hysteresis UVLO Comparator Threshold UVLO Input Resistance RUVLO SYMBOL PGDEL TJ UVLO open circuit, |VIN| increasing UVLO open circuit, percentage of UVLO threshold Referenced to VIN, UVLO open circuit, |VIN| increasing -30 CONDITIONS After |VIN - VOUT| increases above (VPG + PGHYS) MIN 8 TYP 14 140 -28 12 +1.258 95 -26 MAX 20 UNITS ms
o
MAX5911/MAX5912
C
V % V k
Note 1: Note 2: Note 3: Note 4: Note 5:
Minimum ENABLE low pulse width required to unlatch fault condition. The delay from IOUT falling below the zero-current threshold until FAULT is latched low and VOUT is disabled. The time from an output overcurrent or short-circuit condition until the output goes into current limit. The time from VOUT falling until FAULT is asserted low. FAULT is not latched for Power-Not-Good condition. When the device goes into thermal shutdown, the output is disabled and FAULT is latched low.
Typical Operating Characteristics
(VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, RLOAD = 1.8k, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5911 toc01
SUPPLY CURRENT vs. AMBIENT TEMPERATURE
MAX5911 toc02
ON-RESISTANCE vs. AMBIENT TEMPERATURE
ILOAD = 150mA 2.8 ON-RESISTANCE () 2.6 2.4 2.2 2.0 1.8 1.6
MAX5911 toc03
1.8 NO LOAD 1.6 SUPPLY CURRENT (mA)
1.540 NO LOAD 1.535 SUPPLY CURRENT (mA) 1.530 1.525 1.520 1.515 1.510
3.0
1.4
1.2
1.0
0.8 -65 -55 -45 -35 -25 -15 SUPPLY VOLTAGE (V)
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
_______________________________________________________________________________________
3
-48V Simple Swapper Hot-Swap Switches MAX5911/MAX5912
Typical Operating Characteristics (continued)
(VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, RLOAD = 1.8k, TA = +25C, unless otherwise noted.)
MAX5911 TURN-ON WAVEFORMS (RL = 1.8k, CL = NONE)
A 0 0 B B
MAX5911 TURN-ON WAVEFORMS (RL = 1.8k, CL = 47F)
A 0 0
MAX5911 toc04
MAX5911 toc05
MAX5911 TURN-OFF WAVEFORMS (RL = 1.8k, CL = NONE)
A 0 0 B
MAX5911 toc06
C 0 t = 10s/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div
C 0
C 0 t = 2ms/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div A: ENABLE, 5V/div B: VOUT, 20V/div t = 10s/div C: FAULT, 2V/div
MAX5911 TURN-OFF WAVEFORMS (RL = 1.8k, CL = 47F)
A 0 0 B
MAX5911 OVERCURRENT RESPONSE
MAX5911 toc08
MAX5911 toc07
MAX5911 ZERO-CURRENT RESPONSE
A 0 0 B
MAX5911 toc09
A 0 0 B
0 C 0 t = 50ms/div C: FAULT, 2V/div A: FAULT, 5V/div B: VOUT, 50V/div C: IOUT, 200mA/div C C
0
t = 100ms/div A: ENABLE, 5V/div B: VOUT, 20V/div
A: FAULT, 5V/div B: VOUT, 50V/div
t = 50ms/div C: IOUT, 50mA/div
MAX5912 TURN-ON WAVEFORMS (RL = 1.8k, CL = NONE)
A 0 0 B
MAX5911 toc10
MAX5912 TURN-ON WAVEFORMS (RL = 1.8k, CL = 47F)
A 0 0 B
MAX5911 toc11
MAX5912 TURN-OFF WAVEFORMS (RL = 1.8k, CL = NONE)
A 0 0 B
MAX5911 toc12
C 0
C 0 t = 10s/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div A: ENABLE, 5V/div B: VOUT, 20V/div
C 0
t = 1ms/div C: FAULT, 2V/div A: ENABLE, 5V/div B: VOUT, 20V/div
t = 10s/div C: FAULT, 2V/div
4
_______________________________________________________________________________________
-48V Simple Swapper Hot-Swap Switches
Typical Operating Characteristics (continued)
(VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, RLOAD = 1.8k, TA = +25C, unless otherwise noted.)
MAX5912 TURN-OFF WAVEFORMS (RL = 1.8k, CL = 47F)
A 0 0 B B
MAX5911/MAX5912
MAX5911 toc13
MAX5912 OVERCURRENT RESPONSE
A 0 0
MAX5912 ZERO-CURRENT RESPONSE
A 0 0 B
MAX5911 toc14
MAX5911 toc15
0 C 0 t = 100ms/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div A: FAULT, 5V/div B: VOUT, 20V/div t = 40ms/div C: IOUT, 200mA/div C C
0
t = 40ms/div A: FAULT, 5V/div B: VOUT, 20V/div C: IOUT, 100mA/div
Pin Description
PIN MAX5911 1 MAX5912 3 GATE Gate of the Internal Power MOSFET. Normally leave open circuit. To slow down the output voltage ramp, connect two capacitors, one to VIN and one to VOUT. See GATE Connections for details. Voltage Input Terminal. Bypass VIN, to AGND with a 0.1F capacitor to improve noise immunity. Fault Logic Output, open-drain. Tie FAULT to the positive logic supply with a 3.3k resistor. Referenced to DGND. Digital Ground. Ground reference level for the external positive logic, FAULT, and ENABLE. DGND can vary up to 5V with respect to AGND to accommodate differential ground voltages in large systems. ENABLE Input. Turns on and off the internal FET. ENABLE is a positive logiclevel input referenced to DGND. Drive ENABLE high to enable VOUT. Drive ENABLE low to disable VOUT. Pulse ENABLE low to reset the MAX5911/ MAX5912 after a latched fault condition occurs. Analog Ground. Ground reference level for VIN, VOUT, and UVLO. Voltage Output Terminal Undervoltage Lockout Input. Leave UVLO open circuit for default setting of -28V. Alternatively, UVLO can be connected to a resistive divider to set the lockout voltage (see the Changing the Undervoltage Lockout Setting section). The comparator threshold level is +1.258V with respect to VIN. No Connection. No internal connection. NAME FUNCTION
2 3
4, 5, 12, 13 6
VIN FAULT
4
7
DGND
5
10
ENABLE
6 7
11 14
AGND VOUT
8
15
UVLO
--
1, 2, 8, 9, 16
N.C.
_______________________________________________________________________________________
5
-48V Simple Swapper Hot-Swap Switches MAX5911/MAX5912
include an enable input that responds to positive logic, allowing the host system to turn the FET switch on or off. The enable input is also used to reset the devices after an error condition has latched the output FET off.
MAX5911/MAX5912 ENABLE AGND 2.11M GATE UVLO 99.5k +1.258VREF LEVEL SHIFTER CONTROL LOGIC DGND FAULT
Normal Operation
Startup
When power is first applied with ENABLE high, or when ENABLE is asserted, the MAX5911/MAX5912 limit the current to the load to 280mA/415mA. If the output voltage has not reached the power-good threshold within the 14ms power-good delay, FAULT is pulled low. FAULT stays low until the output voltage exceeds the power-good threshold, at which time it is released and becomes high impedance. If VIN UVLO, where UVLO is the desired voltage at which the UVLO fault occurs, FAULT is pulled low and the internal FET is turned off. If the condition persists for over 350ms (IFDEL), the FET is latched off. The default UVLO voltage is -28V, but it can be adjusted using an external resistive divider (see the Changing the Undervoltage Lockout Setting section). Once the FET is latched off, ENABLE must be pulsed low then brought back high to release FAULT and enable VOUT.
VIN
VOUT
Undervoltage Lockout Fault
|VIN|
VPG (min) = 1.8V VPG |VIN - VOUT|, VPG (typ) = 2V VPG (max) = 2.2V |VOUT|
POWER-GOOD HYSTERESIS (5% OF VPG)
0
Thermal Shutdown Fault
POWER GOOD POWER-NOT-GOOD DELAY
Figure 1. Functional Block Diagram
Detailed Description
Figure 1 shows a functional block diagram. The MAX5911/MAX5912 are hot-swap switches for negative supply rails. The devices allow the safe insertion and removal of circuit cards into live backplanes or ports without causing undue glitches on the negative powersupply rail. They operate over the -16V to -65V voltage range. The devices act as a current regulator, using their on-board FET to limit the amount of current drawn from the backplane to 280mA for MAX5911 and 415mA for MAX5912. If the load current exceeds that current limit, the internal switch behaves like a constant current source. The MAX5911/MAX5912 monitor the input voltage, the output voltage, the output current, and the die temperature. They assert their FAULT output if they detect an error condition. A zero-current load disconnect feature activates if the load current drops below 8mA for over 350ms. They also
6
The MAX5911/MAX5912 monitor their internal die temperatures. If the temperature of the die exceeds +140C, FAULT is pulled low and the internal FET is latched off. ENABLE must be pulsed low and then brought high again to reset the FET latch, and release FAULT, provided the die is below the thermal shutdown temperature by 5C (typ).
Power-Not-Good Fault
If |VIN - VOUT| is more than the power-good threshold for over 14ms, FAULT is pulled low. When the output voltage exceeds the power-good threshold, FAULT is released. FAULT output is not latched during a powernot-good fault.
Zero-Current Detection
If the load current drops below 8mA for over 350ms, FAULT is pulled low and the FET is latched off. ENABLE must be pulsed low and then brought high again to release FAULT and enable VOUT.
Applications Information
Chosing A Device
The MAX5911 will output up to 280mA (typ) and the MAX5912 up to 415mA (typ). In applications where high heat is expected, use the MAX5912 for its superior
_______________________________________________________________________________________
-48V Simple Swapper Hot-Swap Switches
FAULT Output
VIN (-16V TO -65V) 0.1F R1 +3.3V R2 3.3k UVLO VIN VOUT
MAX5911/MAX5912
MAX5911 MAX5912 FAULT
The FAULT output is open-drain and is pulled low if the MAX5911/MAX5912 detect an undervoltage fault, a thermal fault, a power-not-good fault, or a zero-current fault. See the Normal Operation section for specific details of fault operation. Connect FAULT to the logic supply with a pullup resistor; 3.3k is sufficient in most cases.
LOAD
Changing the Undervoltage Lockout Setting
The UVLO value defaults to -28V if the UVLO pin is left open circuit. The lockout voltage can be changed with a resistive divider. Connect the divider from V IN to AGND, and connect the center node of the divider to the UVLO pin. Figure 2 shows an example circuit. Use R1 10k, then calculate R2 using:
POSITIVE LOGIC
ENABLE DGND AGND
CHOOSE R1 10k, THEN CALCULATE R2 USING: R2 = R1
VIN (UVLO) 1.258
-1
VIN(UVLO) R2 = R1 x - 1 1.258 where VIN(UVLO) is the desired lockout voltage.
Figure 2. UVLO Voltage Set by an External Resistive Divider
heat dissipation properties, and always solder all of its VIN pins to a large section of circuit board copper.
Logic Control
The enable input responds to +3.3V logic signals and will force the internal FET off if it is pulled low. This feature allows the host to disconnect the load from the power bus if required. Additionally, all fault conditions that latch the internal FET off must be cleared by pulsing ENABLE low for at least 200ns, then reasserting ENABLE before normal operation can resume.
Chip Information
TRANSISTOR COUNT: 1021 PROCESS: BiCMOS
GATE Connections
GATE connects to the gate of the internal N-channel power MOSFET. Normally this pin should be left open circuit. To slow down the voltage ramp at VOUT, connect capacitors from GATE to VOUT and VIN. Size the capacitors so that the GATE to VIN capacitor is ten times the size of the GATE to V OUT capacitor. This technique to slow down the output voltage ramp will also cause the output discharge time to increase if the capacitor values exceed about 1nF. Additionally, this technique will cause the time delay for a power-notgood fault to increase.
_______________________________________________________________________________________
7
-48V Simple Swapper Hot-Swap Switches MAX5911/MAX5912
Package Information
SOICN.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX5911

	To Download MAX5911 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .