Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - hot swap controller -48 V SOIC 8 Surface-mount

General Description

The MAX5920A/MAX5920B are hot-swap controllers that

allow a circuit card to be safely hot plugged into a live

backplane. The MAX5920A/MAX5920B operate from

-20V to -80V and are well-suited for -48V power systems.

These devices are pin and function compatible with the

LT4250 and pin compatible with the LT1640.

The MAX5920A/MAX5920B provide a controlled turn-on

to circuit cards preventing glitches on the power-supply

rail and damage to board connectors and components.

The MAX5920A/MAX5920B provide undervoltage, over-

voltage, and overcurrent protection. These devices

ensure the input voltage is stable and within tolerance

before applying power to the load.

Both the MAX5920A and MAX5920B protect a system

against overcurrent and short-circuit conditions by turn-

ing off the external MOSFET in the event of a fault con-

dition. The MAX5920A/MAX5920B also provide

protection against input voltage steps. During an input

voltage step, the MAX5920A/MAX5920B limit the cur-

rent drawn by the load to a safe level without turning off

power to the load.

Both devices feature an open-drain power-good status

output (PWRGD for the MAX5920A or PWRGD for the

MAX5920B) that can be used to enable downstream

converters. A built-in thermal-shutdown feature is also

included to protect the external MOSFET in case of

overheating.

The MAX5920A/MAX5920B are available in an 8-pin SO

package. Both devices are specified for the extended

-40°C to +85°C temperature range.

Applications

Telecom Line Cards

Network Switches/Routers

Central-Office Line Cards

Server Line Cards

Base-Station Line Cards

Features

♦ Allows Safe Board Insertion and Removal

from a Live -48V Backplane

♦ Pin- and Function-Compatible with LT4250L

(MAX5920A)

♦ Pin-Compatible with LT1640L (MAX5920A)

♦ Pin- and Function-Compatible with LT4250H

(MAX5920B)

♦ Pin-Compatible with LT1640H (MAX5920B)

♦ Circuit-Breaker Immunity to Input Voltage Steps

and Current Spikes

♦ Withstands -100V Input Transients with No

External Components

♦ Programmable Inrush and Short-Circuit Current

Limits

♦ Operates from -20V to -80V

♦ Programmable Overvoltage Protection

♦ Programmable Undervoltage Lockout

♦ Powers Up into a Shorted Load

♦ Power-Good Control Output

♦ Thermal Shutdown Protects External MOSFET

MAX5920

-48V Hot-Swap Controller

with External R

SENSE

________________________________________________________________ Maxim Integrated Products 1

GATE

SENSEV

DRAINOV

PWRGD

(PWRGD)

TOP VIEW

MAX5920A

MAX5920B

( ) FOR MAX5920B.

Pin Configuration

Ordering Information

19-2931; Rev 0; 8/03

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.

PART TEMP RANGE PIN-PACKAGE

MAX5920AESA -40°C to +85°C 8 SO

MAX5920BESA -40°C to +85°C 8 SO

Typical Operating Circuit and Selector Guide appear at end

of data sheet.

Summary of content (18 pages)

PAGE 1
9-2931; Rev 0; 8/03 -48V Hot-Swap Controller with External RSENSE Features ♦ Allows Safe Board Insertion and Removal from a Live -48V Backplane The MAX5920A/MAX5920B provide a controlled turn-on to circuit cards preventing glitches on the power-supply rail and damage to board connectors and components. The MAX5920A/MAX5920B provide undervoltage, overvoltage, and overcurrent protection. These devices ensure the input voltage is stable and within tolerance before applying power to the load.
PAGE 2
MAX5920 -48V Hot-Swap Controller with External RSENSE ABSOLUTE MAXIMUM RATINGS All Voltages are Referenced to VEE, Unless Otherwise Noted. Supply Voltage (VDD - VEE ) .................................-0.3V to +100V DRAIN, PWRGD, PWRGD ....................................-0.3V to +100V PWRGD to DRAIN .............................................… -0.3V to +95V PWRGD to VDD ........................................................-95V to +85V SENSE (Internally Clamped) .................................-0.
PAGE 3
-48V Hot-Swap Controller with External RSENSE MAX5920 ELECTRICAL CHARACTERISTICS (continued) (VEE = 0V, VDD = 48V, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Notes 1, 4) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.1 1.7 2.0 V 1.0 1.6 2.
PAGE 4
Typical Operating Characteristics (VDD = 48V, VEE = 0V, TA = +25°C, unless otherwise noted.) 14 TA = -40°C 400 300 12 11 10 200 9 100 8 0 50 49 48 47 46 7 20 40 60 80 100 0 20 40 60 -40 100 80 10 35 60 TEMPERATURE (°C) GATE PULLUP CURRENT vs. TEMPERATURE GATE PULLDOWN CURRENT vs. TEMPERATURE GATE PULLDOWN CURRENT vs. OVERDRIVE 44.4 44.2 44.0 43.8 43.6 43.4 65 200 60 55 50 45 40 35 43.
PAGE 5
-48V Hot-Swap Controller with External RSENSE MAX5920 R 5kΩ V+ 5V PWRGD/PWRGD OV VDD VS DRAIN VOV 48V VDRAIN MAX5920A MAX5920B VUV UV GATE VEE SENSE VSENSE Figure 1a. Test Circuit 1 PWRGD/PWRGD VDD DRAIN OV VS 48V VS 20V 10kΩ UV MAX5920A MAX5920B 10Ω GATE 0.1µF N IRF530 VUV VEE SENSE 10Ω Figure 1b.
PAGE 6
-48V Hot-Swap Controller with External RSENSE MAX5920 Timing Diagrams 2V 1.255V 2V 1.205V OV 1.255V 1.125V UV 0V 0V tPLHUV tPHLUV tPHLOV tPLHOV GATE GATE Figure 2. OV to GATE Timing 100mV 1V 1V 1V 1V Figure 3. UV to GATE Timing 60mV SENSE UV VEE tPHLCL tPHLSENSE GATE GATE 1V 1V Figure 4a. SENSE to GATE Timing 6 Figure 4b.
PAGE 7
-48V Hot-Swap Controller with External RSENSE DRAIN 1.4V 1.4V ∆VGATE - VGATE = 0V VEE tPHLDL GATE tPHLGH PWRGD 1V PWRGD 1V VEE VEE 1.4V DRAIN VGATE - VGATE = 0V 1.4V GATE VEE VEE tPHLDL tPHLGH PWRGD PWRGD 1V VPWRGD - VDRAIN = 0V 1V VPWRGD - VDRAIN = 0V Figure 5a. DRAIN to PWRGD/PWRGD Timing Figure 5b.
PAGE 8
MAX5920 -48V Hot-Swap Controller with External RSENSE Pin Description PIN MAX5920A MAX5920B 1 — NAME FUNCTION PWRGD Power-Good Signal Output. PWRGD is an active-low open-drain status output referenced to VEE. PWRGD is latched low when VDRAIN - VEE ≤ VDL and VGATE > (∆VGATE - VGH), indicating a power-good condition. PWRGD is open drain otherwise. — 1 PWRGD Power-Good Signal Output. PWRGD is an active-high open-drain status output referenced to DRAIN.
PAGE 9
-48V Hot-Swap Controller with External RSENSE Power-Supply Ramping The MAX5920A/MAX5920B can reside either on the backplane or the removable circuit board (Figure 6a). Power is delivered to the load by placing an external N-channel MOSFET pass transistor in the power-supply path. After the circuit board is inserted into the backplane and the supply voltage at VEE is stable and within the undervoltage and overvoltage tolerance, the MAX5920A/MAX5920B turn on Q1.
PAGE 10
MAX5920 -48V Hot-Swap Controller with External RSENSE INRUSH CURRENT 1A/div voltage of the external MOSFET, thereby reducing the load current. When V SENSE - V EE < V CL , the MAX5920A/MAX5920B pull the GATE pin high by a 45µA (IPU) current. Driving into a Shorted Load GATE - VEE 10V/div DRAIN 50V/div VEE 50V/div CONTACT BOUNCE 4ms/div Figure 6b.
PAGE 11
-48V Hot-Swap Controller with External RSENSE MAX5920 DRAIN 50V/div VEE 20V/div GATE - VEE 10V/div DRAIN 20V/div ID (Q1) 5A/div ID (Q1) 5A/div 400µs/div 1ms/div Figure 7b. Short-Circuit Protection Waveform Figure 8. Voltage Step-On Input Supply -48V RTN (SHORT PIN) -48V RTN R4 549kΩ 1% VDD UV R5 6.49kΩ 1% * R6 10kΩ 1% PWRGD MAX5920A OV VEE SENSE GATE DRAIN R3 1kΩ 5% R7 220Ω 5% R1 0.02Ω 5% -48V *DIODES INC. SMAT70A. D1 BAT85 C2 3.3nF 100V C3 0.
PAGE 12
MAX5920 -48V Hot-Swap Controller with External RSENSE -48V RTN (SHORT PIN) -48V RTN R7 1MΩ 5% C4 1µF 100V R6 549kΩ 1% R4 549kΩ 1% VDD UV NODE1 50V/div NODE1 PWRGD MAX5920A * R6 10kΩ 1% Q2 2N2222 D1 1N4148 OV VEE R5 6.49kΩ 1% SENSE DRAIN R3 1kΩ 5% Q3 ZVN3310 R8 510kΩ 5% GATE P R1 0.02Ω 5% -48V C1 470nF 25V R2 10Ω 5% C3 100µF 100V C2 3.3nF 100V GATE 2V/div 1s/div N Q1 IRF530 *DIODES INC. SMAT70A. Figure 10.
PAGE 13
-48V Hot-Swap Controller with External RSENSE MAX5920 ACTIVE-HIGH ENABLE MODULE -48V RTN (SHORT PIN) -48V RTN VIN+ VOUT+ VDD R4 MAX5920B PWRGD I1 ON/OFF UV N C3 N VGH R5 Q2 Q3 * VIN- VOUT- VEE ∆VGATE VDL OV DRAIN R6 VEE SENSE GATE R3 C2 R2 C1 R1 -48V Q1 *DIODES INC. SMAT70A. Figure 12.
PAGE 14
MAX5920 -48V Hot-Swap Controller with External RSENSE -48V RTN (SHORT PIN) PWRGD -48V RTN R7** 51kΩ 5% R4 549kΩ 1% VDD UV R5 6.49kΩ 1% * R6 10kΩ 1% PWRGD MAX5920A OV VEE SENSE GATE DRAIN R3 1kΩ 5% R1 0.02Ω 5% C1** 470nF 25V R2 10Ω 5% MOC207 C2 15nF 100V C3 100µF 100V -48V *DIODES INC. SMAT70A. **OPTIONAL. Q1 IRF530 Figure 14. Using PWRGD to Drive an Optoisolator pulled high by the module’s internal pullup current source, turning the module off.
PAGE 15
-48V Hot-Swap Controller with External RSENSE Sense Resistor The circuit-breaker current-limit threshold is set to 50mV (typically). Select a sense resistor that causes a drop equal to or above the current-limit threshold at a current level above the maximum normal operating current. Typically, set the overload current to 1.5 to 2.0 times the nominal load current plus the load-capacitance charging current during startup. Choose the sense resistor power rating to be greater than (VCL)2 / RSENSE.
PAGE 16
MAX5920 -48V Hot-Swap Controller with External RSENSE If ICB is set to twice ILOAD, or 5A, VDS momentarily doubles to ≤ 1.25V. If COUT = 4000µF, transient-line input voltage is ∆36V, the 5A charging-current pulse is: 4000µF x 1.25V t= = 1ms 5A Entering the data sheet transient-thermal-resistance curves at 1ms provides a θJC = 0.9°C/W. PD = 6.25W, so ∆tJC = 5.6°C. Clearly, this is not a problem. Example 2: ILOAD = 10A, efficiency = 98%, allowing VDS = 0.96V but RDS(ON) ≤ 96mΩ.
PAGE 17
-48V Hot-Swap Controller with External RSENSE BACKPLANE CIRCUIT CARD -48V RTN -48V RTN (SHORT PIN) VDD UV PWRGD MAX5920A OV VEE SENSE GATE DRAIN VIN+ -48V (INPUT1) LUCENT JW050A1-E INPUT1 N VIN- -48V (INPUT2) INPUT2 Chip Information TRANSISTOR COUNT: 2645 PROCESS: BiCMOS ______________________________________________________________________________________ 17 MAX5920 Typical Operating Circuit
PAGE 18
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) DIM A A1 B C e E H L N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS MAX5920 -48V Hot-Swap Controller with External RSENSE 1.