Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - hot swap controller Multi-purpose TSSOP 20 Surface-mount

General Description

The MAX5923 is a fully integrated Simple Swapper™

hot-swap switch for positive supply rails. The device

allows the safe insertion and removal of circuit cards

into live backplanes or ports without causing glitches

on the power-supply rail. The device also monitors vari-

ous circuit parameters and disconnects the load if a

fault condition occurs, alerting the host with a logic-

level FAULT output. The MAX5923 operates over the

+16V to +60V input voltage range.

During startup, an integrated 0.45Ω power MOSFET

regulates the current and voltage between the back-

plane power source and the load. After startup, the

MOSFET is fully enhanced to reduce its on-resistance.

To ensure robust operation, the MAX5923 contains

built-in safety features that monitor fault conditions and

prevent damage to the internal MOSFET.

The MAX5923 monitors three parameters for fault condi-

tions: zero current, overcurrent, and thermal overload.

The output overcurrent limit counts the time the MAX5923

spends in an overcurrent condition and shuts down the

pass transistor if the current limit is exceeded for the over-

current time limit. The zero-current detection counts the

time the output current is below the zero-current threshold

and shuts down the pass transistor if the counter reaches

the zero-current time limit. The thermal monitoring feature

shuts down the pass transistor if the die temperature

reaches the overtemperature limit. A fault logic output

indicates when an overtemperature or an overcurrent

condition has occurred and a zero-current logic output

indicates if there is a zero-current condition.

An undervoltage detection circuitry keeps the pass tran-

sistor off until the input voltage is above the undervoltage

lockout (UVLO) threshold, which is internally set or can be

set externally with a resistive divider. A power-OK (POK)

output is provided to signal when the output voltage has

reached to within 0.75V of the input voltage. An Enable

input allows the host system to disconnect the system

from the load and/or reset a fault condition by toggling

Enable.

The MAX5923 is available in a 20-pin TSSOP package

and operates in the extended -40°C to +85°C tempera-

ture range.

Applications

Features

♦ Wide Operating Input Range: +16V to +60V

♦ 0.45Ω Integrated Power Switch

♦ Programmable Output Current Up to 800mA

♦ Over/Undercurrent-Limit Detection

♦ Input Logic Signals Compatible with 1.8V to 5V

CMOS Logic

♦ Separate Analog and Digital Grounds with Up to

±4V Offset

♦ Power-OK Status Output

♦ Overcurrent Protection with Status Outputs

♦ Built-In Thermal Shutdown

♦ Internal Switch Protection Circuitry

♦ Current-Limit Foldback with Timeout and Duty-

Cycle Control

♦ Latch or Autorestart Fault Management

MAX5923

+60V Simple Swapper Hot-Swap Switch

________________________________________________________________ Maxim Integrated Products 1

19-2850; Rev 0; 4/03

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

MAX5923EUP -40°C to +85°C 20 TSSOP

Ordering Information

Pin Configuration appears at end of data sheet.

Typical Operating Circuit

+1.65V TO +5.5V

OFF

SENSE

+16V TO +60V

MAX5923

DRAIN

UVLO

ALL SIGNAL AND DIGITAL INPUTS/OUTPUTS ARE REFERENCED TO DGND.

DGND CAN BE ±4V FROM AGND_S.

AGND_S

DGND

POK

FAULT

ZC_EN

LATCH

VDIG

OUT

Simple Swapper is a trademark of Maxim Integrated Products, Inc.

Network Routers/Switches

Current Limiter

Servers

Industrial Equipment

Summary of content (12 pages)

PAGE 1
9-2850; Rev 0; 4/03 +60V Simple Swapper Hot-Swap Switch During startup, an integrated 0.45Ω power MOSFET regulates the current and voltage between the backplane power source and the load. After startup, the MOSFET is fully enhanced to reduce its on-resistance. To ensure robust operation, the MAX5923 contains built-in safety features that monitor fault conditions and prevent damage to the internal MOSFET.
PAGE 2
MAX5923 +60V Simple Swapper Hot-Swap Switch ABSOLUTE MAXIMUM RATINGS All Voltages with Respect to AGND_S, Unless Otherwise Noted IN ............................................................................-0.3V to +76V UVLO ........................................................................-0.3V to +6V VDIG to DGND .........................................................-0.3V to +6V OUT .......................................................-0.3V to (VDRAIN + 0.3V) DRAIN ..........................
PAGE 3
+60V Simple Swapper Hot-Swap Switch (VIN = 48V, VDIG = 3.3V, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω ±1%, UVLO = open, EN = VDIG, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER POK Output Delay (Note 5) Zero-Current Detection Threshold Voltage (VIN - VDRS) ZC Output Low Voltage SYMBOL MIN TYP MAX POK from high to low, VOUT falling 1 1.4 1.8 tPOK_HIGH POK from low to high, VOUT rising 74 88 102 2.7 3.75 4.
PAGE 4
Typical Operating Characteristics (VIN = 48V, VDIG, EN, LATCH, CLASS, ZC_EN = 3.3V, DCA, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω, UVLO floating, TA = +25°C, unless otherwise noted.) VIN SUPPLY CURRENT vs. TEMPERATURE TA = +85°C 0.85 TA = +25°C 0.80 MAX5923 toc02 12.0 VIN = 60V 11.9 11.8 11.7 0.90 0.85 IDIG (µA) SUPPLY CURRENT (mA) 0.90 MEASURED AT AGND 0.95 SUPPLY CURRENT (mA) MEASURED AT AGND 0.95 1.00 MAX5923 toc01 1.00 DIGITAL SUPPLY CURRENT vs.
PAGE 5
+60V Simple Swapper Hot-Swap Switch OVERCURRENT TIMEOUT (RLOAD FROM 240Ω TO 75Ω) IDIG (µA) DIGITAL SUPPLY CURRENT vs. VDIG MAX5923 toc11 MAX5923 toc10 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 20V/div VOUT 0V 5V/div POK 0V 200mA/div IOUT 0A 5V/div FAULT 0V 0 1.0 2.0 3.0 4.0 5.0 6.
PAGE 6
MAX5923 +60V Simple Swapper Hot-Swap Switch Typical Operating Characteristics (continued) (VIN = 48V, VDIG, EN, LATCH, CLASS, ZC_EN = 3.3V, DCA, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω, UVLO floating, TA = +25°C, unless otherwise noted.
PAGE 7
+60V Simple Swapper Hot-Swap Switch OUTPUT SHORT-CIRCUIT RESPONSE OUTPUT SHORT-CIRCUIT RESPONSE MAX5923 toc22 MAX5923 toc23 IOUT 10A/div IOUT 200mA/div VOUT VOUT 20V/div 20V/div 4µs/div 200µs/div Pin Description PIN NAME FUNCTION — AGND Analog Ground. This is the return of analog power input. AGND can vary ±4V from DGND. AGND and DGND must be connected together at a single point in the system. 1, 2 DRAIN Drain connection for the integrated MOSFET.
PAGE 8
MAX5923 +60V Simple Swapper Hot-Swap Switch Pin Description (continued) PIN NAME FUNCTION 13 DGND Digital Ground. DGND can vary ±4V from AGND. DGND and AGND must be connected together at a single point in the system. 14 LATCH Fault Management Selection Digital Input. Referenced to DGND. Connect to logic high to latch off after a fault condition. Connect to logic low for automatic restart after a fault condition (see the Fault Management section).
PAGE 9
+60V Simple Swapper Hot-Swap Switch MAX5923 VIN = 16V TO 60V VILM IN R1 MAX5923 UVLO VILM/3 R2 AGND VFBSTART (2V) Figure 1. Setting Undervoltage Lockout with an External Resistive Divider Digital Logic VDIG is the input supply for the internal logic circuitry. The logic input thresholds of EN, LATCH, and ZC_EN are CMOS compatible and are determined by the voltage at VDIG, which can range from 1.65V to 5.5V. The POK and FAULT outputs are open-drain.
PAGE 10
+60V Simple Swapper Hot-Swap Switch MAX5923 Zero-Current Detection Zero-current detection is enabled if ZC_EN is high and only after the startup period has finished (indicated by POK going high). When VSENSE falls below the zerocurrent threshold (VZCTH) for a continuous tZCDEL = 350ms, a zero-current fault is generated. The MOSFET is turned off and ZC is latched low. ZC is open drain during initial power-up.
PAGE 11
+60V Simple Swapper Hot-Swap Switch +16V TO +60V IN 100µF (100V) 0.5Ω (1W) OUT 1µF (100V) D1 B1100LB (100V, 1A) +1.65V TO +5.5V 100Ω VDIG DRAIN 0.1µF 2kΩ 10µF MAX5923 UVLO ON OFF LATCH ZC_EN EN 2kΩ 2kΩ ZC FAULT 1Ω (1/16W) POK AGND_S DGND ALL SIGNAL AND DIGITAL INPUTS/OUTPUTS ARE REFERENCED TO DGND. DGND CAN BE ±4V FROM AGND_S. Pin Configuration Chip Information TRANSISTOR COUNT: 8,687 PROCESS: BiCMOS TOP VIEW DRAIN 1 20 OUT DRAIN 2 19 N.C. IN 3 18 N.C. N.C.
PAGE 12
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.) TSSOP4.40mm.EPS MAX5923 +60V Simple Swapper Hot-Swap Switch 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.