Datasheet

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

General Description

The MAX5948A/MAX5948B are hot-swap controllers

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

live backplane. The MAX5948A/MAX5948B operate

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

systems. The MAX5948A is pin- and function-compati-

ble with both the LT1640AL and LT1640L. The

MAX5948B is pin- and function-compatible with both

the LT1640AH and LT1640H.

The MAX5948A/MAX5948B provide a controlled turn-on

to circuit cards preventing glitches on the power-supply

rail and damage to board connectors and components.

The MAX5948A/MAX5948B 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 MAX5948A and MAX5948B protect a system

against overcurrent and short-circuit conditions by turning

off the external MOSFET in the event of a fault condition.

Both devices feature an open-drain power-good status

output, PWRGD for MAX5948A or PWRGD for

MAX5948B, that can be used to enable downstream

converters.

The MAX5948A/MAX5948B are available in an 8-pin SO

package. Both devices are specified for the extended

-40°C to +85°C temperature range.

Applications

Central-Office Switching

Network Switches/Routers

Server Line Cards

Base-Station Line Cards

Features

o Allow Safe Board Insertion and Removal from a

Live -48V Backplane

o Pin- and Function-Compatible with

LT1640AL/LT1640L (MAX5948A)

o Pin- and Function-Compatible with

LT1640AH/LT1640H (MAX5948B)

o Withstand -100V Input Transients with No

External Components

o Operate from -20V to -80V

o Programmable Inrush and Short-Circuit Current

Limits

o Programmable Overvoltage Protection

o Programmable Undervoltage Lockout

o Power Up into a Shorted Load

o Power-Good Control Output

MAX5948A/MAX5948B

-48V Hot-Swap Controllers

with External R

SENSE

________________________________________________________________

Maxim Integrated Products

GATE

SENSEV

DRAINOV

PWRGD

(PWRGD)

TOP VIEW

MAX5948A

MAX5948B

( ) FOR MAX5948B.

Pin Configuration

19-3473; Rev 1; 8/11

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Typical Operating Circuit appears at end of data sheet.

Selector Guide

PART PWRGD POLARITY

MAX5948AESA Active Low (PWRGD)

MAX5948BESA Active High (PWRGD)

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX5948AESA+ -40°C to +85°C 8 SO

MAX5948BESA+ -40°C to +85°C 8 SO

Denotes a lead(Pb)-free/RoHS-compliant package.

Summary of content (18 pages)

PAGE 1
9-3473; Rev 1; 8/11 -48V Hot-Swap Controllers with External RSENSE The MAX5948A/MAX5948B are hot-swap controllers that allow a circuit card to be safely hot plugged into a live backplane. The MAX5948A/MAX5948B operate from -20V to -80V and are well-suited for -48V power systems. The MAX5948A is pin- and function-compatible with both the LT1640AL and LT1640L. The MAX5948B is pin- and function-compatible with both the LT1640AH and LT1640H.
PAGE 2
MAX5948A/MAX5948B -48V Hot-Swap Controllers with External RSENSE ABSOLUTE MAXIMUM RATINGS (All voltages are referenced to VEE, unless otherwise noted.) Supply Voltage (VDD - VEE ) .................................-0.3V to +100V PWRGD, PWRGD .................................................-0.3V to +100V DRAIN (Note 1)........................................................-2V to +100V SENSE ....................................................................-0.3V to +20V GATE (internally clamped) .........
PAGE 3
-48V Hot-Swap Controllers with External RSENSE MAX5948A/MAX5948B ELECTRICAL CHARACTERISTICS (continued) (VEE = 0V, VDD = 48V, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.
PAGE 4
Typical Operating Characteristics (VDD = 48V, VEE = 0V, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. SUPPLY VOLTAGE 0.9 0.8 SUPPLY CURRENT (mA) 700 600 500 400 300 MAX5948 toc02 800 SUPPLY CURRENT (µA) SUPPLY CURRENT vs. TEMPERATURE 1.0 MAX5948 toc01 900 0.7 0.6 0.5 0.4 0.3 200 0.2 100 0.1 0 0 0 10 20 30 40 50 60 70 80 90 100 -50 -25 SUPPLY VOLTAGE (V) 0 25 50 75 100 TEMPERATURE (°C) GATE VOLTAGE vs. SUPPLY VOLTAGE GATE VOLTAGE vs. TEMPERATURE 14 MAX5948 toc04 15.
PAGE 5
-48V Hot-Swap Controllers with External RSENSE 50 45 40 35 IOUT = 1mA 30 35 10,000 OUTPUT IMPEDANCE (GΩ) 55 40 MAX5948 toc08 VGATE = 2V PWRGD OUTPUT LOW VOLTAGE (mV) MAX5948 toc07 60 GATE PULLDOWN CURRENT (mA) PWRGD OUTPUT IMPEDANCE vs. TEMPERATURE (MAX5948B) PWRGD OUTPUT LOW VOLTAGE vs. TEMPERATURE (MAX5948A) 30 25 20 15 10 1000 100 10 5 0 -50 -25 0 25 50 75 100 MAX5948 toc09 GATE PULLDOWN CURRENT vs.
PAGE 6
MAX5948A/MAX5948B -48V Hot-Swap Controllers with External RSENSE Timing Diagrams 2V 2V 1.223V 1.203V OV 1.243V 1.223V UV 0V 0V tPLHUV tPHLUV tPHLOV tPLHOV GATE GATE 1V 1V 1V Figure 3. OV to GATE Timing 1V Figure 4. UV to GATE Timing 1.8V 1.4V DRAIN VEE DRAIN 100mV tPHLPG 50mV SENSE PWRGD VEE 1V 1V VEE tPHLSENSE 1.8V 1.4V DRAIN GATE 0V 1V PWRGD tPLHPG tPHLPG 1V 1V VPWRGD - VDRAIN = 0V Figure 5. SENSE to GATE Timing 6 Figure 6.
PAGE 7
-48V Hot-Swap Controllers with External RSENSE PIN MAX5948A MAX5948B NAME FUNCTION 1 — PWRGD Power-Good Signal Output. PWRGD is an active-low open-drain status output referenced to VEE. PWRGD is low when VDRAIN - VEE ≤ VPG, 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. PWRGD is in a high-impedance state when VDRAIN - VEE ≤ VPG, indicating a power-good condition.
PAGE 8
-48V Hot-Swap Controllers with External RSENSE MAX5948A/MAX5948B Block Diagram VDD UV VCC AND REFERENCE GENERATOR VCC MAX5948A MAX5948B REF REF OUTPUT DRIVE PWRGD PWRGD LOGIC AND GATE DRIVE OV 50mV VPG VEE VEE SENSE GATE DRAIN Power-Supply Ramping Board Removal The MAX5948A/MAX5948B 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 powersupply path.
PAGE 9
-48V Hot-Swap Controllers with External RSENSE MAX5948A/MAX5948B -48V RTN (SHORT PIN) -48V RTN VICOR VI-J3D-CY R4 562kΩ 1% C3 0.1µF 100V VDD UV R5 9.09kΩ 1% * R6 10kΩ 1% PWRGD C4 100µF 100V VIN+ GATE IN MAX5948B OV VEE SENSE GATE DRAIN R3 18kΩ 5% R1 0.02Ω 5% C1 150nF 25V VIN- C2 3.3nF 100V R2 10Ω 5% -48V Q1 IRF530 *DIODES INC. SMAT70A. Figure 7a.
PAGE 10
MAX5948A/MAX5948B -48V Hot-Swap Controllers with External RSENSE ⎛ V −V ⎞ t cbdly = R7 × C3 × In ⎜ f I ⎟ ⎝ Vf − VCB ⎠ INRUSH CURRENT 2A/div ⎛ I −I ⎞ = R7 × C3 × In ⎜ f I ⎟ ⎝ If − ICB ⎠ GATE - VEE 5V/div CONTACT BOUNCE where If is the current in fault condition, II is the initial current before the fault, and ICB is the circuit-breaker trip current (ICB = VCB/R1). Alternatively, the corresponding voltages across the sense resistor (Vf, VI, and V CB ) may be used in the equation as shown.
PAGE 11
-48V Hot-Swap Controllers with External RSENSE Undervoltage and Overvoltage Protection The UV and OV pins can be used to detect undervoltage and overvoltage conditions. The UV and OV pins are internally connected to analog comparators with 20mV of hysteresis. When the UV voltage falls below its threshold or the OV voltage rises above its threshold, the GATE pin is immediately pulled low.
PAGE 12
MAX5948A/MAX5948B -48V Hot-Swap Controllers with External RSENSE Figure 11a shows how to program the undervoltage and overvoltage trip thresholds using three resistors. With R4 = 562kΩ, R5 = 9.09kΩ, and R6 = 10kΩ, the undervoltage threshold is set to 37.2V (with a 37.8V release from undervoltage) and the overvoltage is set to 71.1V (with a 69.9V release from overvoltage). More hysteresis can be added to the undervoltage lockout with the circuit shown in Figure 11b.
PAGE 13
-48V Hot-Swap Controllers with External RSENSE MAX5948A/MAX5948B VICOR VI-J3D-CY -48V RTN (SHORT PIN) -48V RTN VIN+ VOUT+ VDD R4 MAX5948B PWRGD I1 ON/OFF UV Q2 C4 Q3 VPG R5 VIN- VOUT- VEE * OV DRAIN R6 VEE SENSE GATE R3 C2 R2 C1 R1 -48V Q1 *DIODES INC. SMAT70A. Figure 12. Active-High Enable Module A separate resistor-divider must be used for the overvoltage lockout setting. The supply overvoltage lockout threshold is: ⎛ R4 + R5 ⎞ VOV = VOVH ⎜ ⎟ ⎝ R5 ⎠ where VOVH is typically 1.223V.
PAGE 14
MAX5948A/MAX5948B -48V Hot-Swap Controllers with External RSENSE ACTIVE-HIGH ENABLE MODULE -48V RTN (SHORT PIN) -48V RTN VIN+ VOUT+ VDD R4 MAX5948A PWRGD ON/OFF UV C4 R5 Q2 VPG VIN- VOUT- VEE * OV DRAIN R6 VEE SENSE GATE R3 C2 R2 C1 R1 -48V Q1 *DIODES INC. SMAT70A. Figure 13.
PAGE 15
-48V Hot-Swap Controllers with External RSENSE MAX5948A/MAX5948B PWRGD GND R7 51kΩ 5% GND (SHORT PIN) R4 562kΩ 1% VDD UV R5 9.09kΩ 1% * R6 10kΩ 1% PWRGD MAX5948A OV VEE SENSE GATE DRAIN R3 18kΩ 5% R1 0.02Ω 5% MOC207 C2 3.3nF 100V C3 100µF 100V R2 10Ω 5% C1 150nF 25V -48V Q1 IRF530 *DIODES INC. SMAT70A. Figure 14. Using PWRGD to Drive an Optoisolator Applications Information 50mV ICB Realize that ICB varies ±20% due to trip-voltage tolerance.
PAGE 16
-48V Hot-Swap Controllers with External RSENSE MAX5948A/MAX5948B Typical Operating Circuit GND GND (SHORT PIN) R4 562kΩ 1% VDD UV R5 9.09kΩ 1% * R6 10kΩ 1% PWRGD MAX5948A OV VEE SENSE GATE DRAIN R3 18kΩ 5% C2 3.3nF 100V VIN+ R1 0.02Ω 5% R2 10Ω 5% C1 150nF 25V -48V Q1 IRF530 *DIODES INC. SMAT70A. • 150µs C2 • Set R2 = 10Ω.
PAGE 17
-48V Hot-Swap Controllers with External RSENSE t= 4000µF x 1.25V = 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. An IRF530 in a D2PAK exhibits RDS(ON) ≤ 90mΩ at +25°C and ≤ 135mΩ at +80°C. Power dissipation is 9.6W at +25°C or 14.4W at +80°C. Junction-to-case thermal resistance is 1.
PAGE 18
Revision History REVISION NUMBER REVISION DATE 0 10/04 Initial release 1 8/11 Updated Ordering Information, Absolute Maximum Ratings, Electrical Characteristics, and Package Information. DESCRIPTION PAGES CHANGED — 1, 2, 3, 17 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.