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Linear Technology LTC4260 Datasheet

Positive high voltage hot swap controller with i2c compatible monitoring
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FeaTures
Allows Safe Board Insertion into Live Backplane
n
8-Bit ADC Monitors Current and Voltage
n
2
I
C™/SMBus Interface
n
Wide Operating Voltage Range: 8.5V to 80V
n
High Side Drive for External N-Channel MOSFET
n
Input Overvoltage/Undervoltage Protection
n
Optional Latchoff or Autoretry After Faults
n
Alerts Host After Faults
n
Foldback Current Limiting
n
Available in 24-Lead SO, 24-Lead Narrow
n
SSOP and 32-Lead (5mm × 5mm) QFN Packages
applicaTions
Electronic Circuit Breakers
n
Live Board Insertion
n
Computers, Servers
n
Typical applicaTion
3A, 48V Card Resident Application
48V
0.1µF
*
SDA
SCL
ALERT
GND
BACKPLANE PLUG-IN
CARD
*DIODES INC. SMBT70A
0.010
FDB3632
49.9k
10
100k
6.8nF
1.74k
UV
V
SENSE
GATE
DD
2.67k
OV
SDAO
SDAI
LTC4260
SCL
ALERT
ON
INTV
TIMER
GND
CC
0.1µF
68nF
For more information
Positive High Voltage
Hot Swap Controller with
2
I
C Compatible Monitoring
DescripTion
The
LTC
4260
Hot Swap™ controller allows a board to be
®
safely inserted and removed from a live backplane. Using
an external N-channel pass transistor, the board supply
voltage can be ramped up at an adjustable rate. An I
interface and onboard ADC allow monitoring of board
current, voltage and fault status.
The device features adjustable analog foldback current
limit with latch off or automatic restart after the LTC4260
remains in current limit beyond an adjustable time-out
delay.
The controller has additional features to interrupt the host
when a fault has occurred, notify when output power is
good, detect insertion of a load card and power-up in
either the on or off state.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
V
OUT
+
48V
C
V
L
IN
43.5k
50V/DIV
I
IN
2A/DIV
3.57k
SOURCE
V
OUT
50V/DIV
FB
BD_PRST
GPIO
ADIN
24k
5V/DIV
GPIO
4260 TA01
www.linear.com/LTC4260
LTC4260
Power Up Waveforms
C
= 1000F
L
25ms/DIV
2
C
4260 TA02
4260fc
1

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Summary of Contents for Linear Technology LTC4260

  • Page 1 Electronic Circuit Breakers Live Board Insertion L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the Computers, Servers property of their respective owners.

  • Page 2: Absolute Maximum Ratings

    LTC4260 absoluTe MaxiMuM raTings (Notes 1, 2) Supply Voltages (V ) ......– 0.3V to 100V ALERT, SDAO ..........–0.3V to 6.5V Input Voltages Supply Voltage (INTV ) ......–0.3V to 6.2V SENSE ......V – 10V or –0.3V to V Operating Temperature Range SOURCE ......

  • Page 3: Electrical Characteristics

    LTC4260 elecTrical characTerisTics denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. V = 48V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS UNITS General Input Supply Range Input Supply Current Supply Undervoltage Lockout Falling 7.45...
  • Page 4 LTC4260 elecTrical characTerisTics denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. V = 48V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS UNITS Timer TIMER Pin High Threshold Rising 1.235 1.28 TIMER(H)
  • Page 5 LTC4260 elecTrical characTerisTics denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25°C. V = 48V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS UNITS C Interface Timing (Note 4) Maximum SCL Clock Frequency Operates with f ≤...

  • Page 6: Typical Performance Characteristics

    LTC4260 Typical perForMance characTerisTics = 25°C, V = 48V unless otherwise noted. UV Low-High Threshold vs V INTV vs I vs Temperature LOAD 3.54 = 48V 3.52 = 12V 85°C 25°C 3.50 –40°C 3.48 MAX I = 4.5 mA LOAD...
  • Page 7 LTC4260 Typical perForMance characTerisTics = 25°C, V = 48V unless otherwise noted. Pull Up vs Temperature Gate Drive vs I Gate Drive vs V GATE GATE –25 85°C = 80V 25°C –40°C = 48V –20 –15 = 12V –10 –10 –5...

  • Page 8: Pin Functions

    LTC4260 pin FuncTions ADIN: ADC Input. A voltage between 0V and 2.56V applied GND: Device Ground. to this pin can be measured by the onboard ADC. Tie to GPIO: General Purpose Input/Output. Open-drain logic ground if unused. output and logic input. Defaults to pull low to indicate ADR0 to ADR2: Serial Bus Address Inputs.
  • Page 9 LTC4260 pin FuncTions SDAO: Serial Bus Data Output. Open-drain output used for TIMER: Timer Input. Connect a capacitor between this pin sending data back to the master controller or acknowledg- and ground to set a 12ms/µF duration for current limit ing a write operation.

  • Page 10: Functional Diagram

    LTC4260 FuncTional DiagraM UH ONLY SENSE INTERNAL GATE – POWER CHARGE 3.5V 20mV TO PUMP 50mV 16.5V + – GATE – SOURCE DRIVER FOLDBACK – GN/UH ONLY – 3.5V PWRGD FET ON – 3.5V 1.235V RESET GPIO – INTV LOGIC –...

  • Page 11: Timing Diagram

    The Functional Diagram displays the main functional areas 0.2V (comparator TM1) which tells the logic that the pass of this device. The LTC4260 is designed to turn a board’s transistor has cooled and it is safe to turn it on again.
  • Page 12 C periodically and reads the stored information. acceptable range and the BDPRST pin must be pulled The basic LTC4260 application circuit is shown in Figure 1. low. All of these conditions must be satisfied for dura- External component selection is discussed in detail in the tion of 100ms to ensure that any contact bounce during Design Example section.

  • Page 13: Overcurrent Fault

    Overcurrent Fault + 13V GATE The LTC4260 features an adjustable current limit with fold- back that protects against short circuits or excessive load SLOPE = 18µA/C1 current. To protect against excessive power dissipation in the switch during active current limit, the available current is reduced as a function of the output voltage sensed by the FB pin.

  • Page 14: Overvoltage Fault

    FET shuts off (see a load card. In cases where the LTC4260 and the switch Supply Transients). Following this event, the part may turn reside on a backplane or midplane and the load resides on again after a delay (typically the 100ms normal turn-on on a plug-in card, the BDPRST pin can be used to detect...

  • Page 15: Resetting Faults

    0.4V resolution (divider converts 102.4V to 2.56V). The the bus master controller broadcasts the Alert Response ADIN pin is monitored with a 2.56V full scale and 10mV Address, the LTC4260 responds with its address on the resolution, and the voltage between the V and SENSE SDA line and releases ALERT as shown in Figure 11.
  • Page 16 Supply Transient Protection of 8.5V, the minimum gate drive voltage is 4.5V. When The LTC4260 is 100% tested and guaranteed to be safe from the input supply voltage is higher than 20V, the gate damage with supply voltages up to 100V. However, spikes drive is at least 10V and a regular N-FET can be used.
  • Page 17 LTC4260 applicaTions inForMaTion The SOA (safe operating area) curves of candidate FETs Layout Considerations must be evaluated to ensure that the heat capacity of the To achieve accurate current sensing, a Kelvin connection package can stand 24W for 16ms. The SOA curves of the is recommended.

  • Page 18: Digital Interface

    Using Optoisolators with SDA After the last byte has been received the master will leave The LTC4260 separates the SDA line into SDAI and SDAO. the SDA line HIGH (not acknowledge) and issue a STOP If optoisolators are not used then tie SDAI and SDAO condition to terminate the transmission.
  • Page 19 Alert Response Address (0001 100)b with sends the contents of the requested register. The transmis- the R/W bit set to one. Any LTC4260 that is pulling its sion is ended when the master sends a STOP condition.
  • Page 20 FROM SLAVE TO MASTER R: READ BIT (HIGH) W: WRITE BIT (LOW) S: START CONDITION P: STOP CONDITION 4260 F07 Figure 7. LTC4260 Serial Bus SDA Write Byte Protocol ADDRESS COMMAND DATA DATA 1 0 a4:a0 X X X X X b2:b0...
  • Page 21 LTC4260 applicaTions inForMaTion Table 1. LTC4260 I C Device Addressing HEX DEVICE LTC4260 ADDRESS DESCRIPTION BINARY DEVICE ADDRESS ADDRESS PINS ADR2 ADR1 ADR0 Mass Write Alert Response 4260fc For more information www.linear.com/LTC4260...
  • Page 22 LTC4260 applicaTions inForMaTion Table 2. LTC4260 Register Addresses and Contents REGISTER REGISTER NAME ADDRESS* READ/WRITE DESCRIPTION CONTROL (A) Controls Whether the Part Retries After Faults, Set the Switch State ALERT (B) Controls Whether the ALERT Pin is Pulled Low After a Fault is Logged in the Fault Register...
  • Page 23 LTC4260 applicaTions inForMaTion Table 4. ALERT Register B (01h)—Read/Write NAME OPERATION Reserved Not Used GPIO Output Output Data Bit to GPIO Pin When Configured as Output. Defaults to 0 FET Short Alert Enables Alert for FET Short Condition 1 = Enable Alert, 0 = Disable Alert (Default) BDPRST State Change Alert...
  • Page 24 LTC4260 applicaTions inForMaTion Table 6. FAULT Register D (03h)—Read/Write NAME OPERATION D7:6 Reserved FET Short Fault Occurred Indicates Potential FET Short was Detected When Measured Current Sense Voltage Exceeded 2mV (code 0000111) While FET was Off 1 = FET was Shorted, 0 = FET is Good Board Present Changes State Indicates that a Board was Inserted or Extracted When BDPRST Changed State...
  • Page 25 LTC4260 applicaTions inForMaTion 0.003 Si7880DP 6.65k 1000µF 5.76k 100k 2.94k 0.1µF 22nF SENSE GATE SOURCE 2.05k 100k SDAO ADIN SDAI LTC4260GN GPIO BD_PRST ALERT ALERT TIMER INTV ADR0 ADR1 ADR2 0.68µF 4260 F12 0.1µF BACKPLANE PLUG-IN CARD Figure 12. 12A, 12V Card Resident Application 0.01...

  • Page 26: Package Description

    LTC4260 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. GN Package 24-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641 Rev B) .337 – .344* (8.560 – 8.738) .033 (0.838) 15 1413 .045 ±.005 .229 –...
  • Page 27 LTC4260 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. SW Package 24-Lead Plastic Small Outline (Wide .300 Inch) (Reference LTC DWG # 05-08-1620) .050 BSC .045 ±.005 .030 ±.005 .598 – .614 (15.190 – 15.600) NOTE 4 20 19 .325 ±.005...
  • Page 28 LTC4260 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. UH Package 32-Lead Plastic QFN (5mm × 5mm) (Reference LTC DWG # 05-08-1693 Rev D) 0.70 ±0.05 5.50 ±0.05 4.10 ±0.05 3.45 ± 0.05 3.50 REF (4 SIDES) 3.45 ±...

  • Page 29: Revision History

    Changed SMAT70B to SMBT70A in the Typical Application 4260fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- For more information www.linear.com/LTC4260...

  • Page 30: Typical Application

    N-Channel, 9V to 80V, MSOP-8 and DFN-6 Packages 4260fc Linear Technology Corporation LT 0513 REV C • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTC4260 (408) 432-1900 FAX: (408) 434-0507 www.linear.com/LTC4260  LINEAR TECHNOLOGY CORPORA TION 2004 ● ●...

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