LT1640AL LINER [Linear Technology], LT1640AL Datasheet

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LT1640AL

Manufacturer Part Number
LT1640AL
Description
Negative Voltage Hot Swap Controllers
Manufacturer
LINER [Linear Technology]
Datasheet

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FEATURES
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APPLICATIONS
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TYPICAL APPLICATION
(SHORT PIN)
Please See LTC4252B/LTC4252C for Drop-In Replacement
Allows Safe Board Insertion and Removal from a
Live – 48V Backplane
Floating Topology Permits Very High Voltage Operation
Programmable Analog Current Limit With Circuit
Breaker Timer
Fast Response Time Limits Peak Fault Current
Programmable Soft-Start Current Limit
Programmable Timer with Drain Voltage
Accelerated Response
±1% Undervoltage/Overvoltage Threshold Accuracy
(LTC4252A)
Adjustable Undervoltage/Overvoltage Protection
LTC4252-1/LTC4252A-1: Latch Off After Fault
LTC4252-2: Automatic Retry After Fault
Available in 8-Pin and 10-Pin MSOP Packages
Hot Board Insertion
Electronic Circuit Breaker
– 48V Distributed Power Systems
Negative Power Supply Control
Central Office Switching
High Availability Servers
ATCA
–48RTN
–48RTN
NOT RECOMMENDED FOR NEW DESIGNS
–48V
32.4k
402k
1%
1%
* M0C207
**DIODES, INC
R1
R2
C1
10nF
–48V/2.5A Hot Swap Controller
D
DDZ13B
RECOMMENDED FOR HARSH ENVIRONMENTS
IN
C
0.33μF
T
**
UV
TIMER
OV
SS
C
68nF
SS
LTC4252-1
V
V
EE
IN
R
3× 1.8k IN SERIES
1/4W EACH
PWRGD
SENSE
DRAIN
IN
GATE
C
1μF
IN
R
D
1M
R3
5.1k
R
10Ω
C
C
18nF
C
*
+
Q1
IRF530S
V
R
0.02Ω
425212 TA01
OUT
S
C
100μF
L
EN
LOAD
DESCRIPTION
The LTC
allows a board to be safely inserted and removed from a
live backplane. Output current is controlled by three stages
of current limiting: a timed circuit breaker, active current
limiting and a fast feedforward path that limits peak current
under worst-case catastrophic fault conditions.
Adjustable undervoltage and overvoltage detectors dis-
connect the load whenever the input supply exceeds the
desired operating range. The LTC4252’s supply input is
shunt regulated, allowing safe operation with very high
supply voltages. A multifunction timer delays initial start-
up and controls the circuit breaker’s response time. The
circuit breaker’s response time is accelerated by sensing
excessive MOSFET drain voltage, keeping the MOSFET
within its safe operating area (SOA). An adjustable soft-
start circuit controls MOSFET inrush current at start-up.
The LTC4252-1/LTC4252A-1 latch off after a circuit breaker
fault times out. The LTC4252-2 provides automatic retry
after a fault. The LTC4252A-1/LTC4252A-2 feature tight
±1% undervoltage/overvoltage threshold accuracy. The
LTC4252 is available in either an 8-pin or 10-pin MSOP .
L, LT, LTC, LTM, 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.
LTC4252A-1/LTC4252A-2
®
4252 negative voltage Hot Swap
Hot Swap Controllers
2.5A/DIV
LTC4252-1/LTC4252-2
20V/DIV
10V/DIV
PWRGD
5V/DIV
SENSE
GATE
V
OUT
Negative Voltage
Start-Up Behavior
1ms/DIV
TM
controller
425212 TA01a
425212fd
1

Related parts for LT1640AL

LT1640AL Summary of contents

Page 1

NOT RECOMMENDED FOR NEW DESIGNS Please See LTC4252B/LTC4252C for Drop-In Replacement FEATURES n Allows Safe Board Insertion and Removal from a Live – 48V Backplane n Floating Topology Permits Very High Voltage Operation n Programmable Analog Current Limit With Circuit ...

Page 2

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 ABSOLUTE MAXIMUM RATINGS All Voltages Referred to V (Note 1) EE Current into V (100μs Pulse) .............................100mA DRAIN Pin Minimum Voltage ........................ – 0.3V IN Input/Output Pins (Except SENSE and DRAIN) Voltage .......... –0.3V to ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER V V – V Zener Voltage – V Zener Dynamic Impedance Supply Current Undervoltage Lockout ...

Page 4

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER I TIMER Pin Current TMR Δ 50μA) – TMRACC TMR DRN TMR ΔI 0μA)]/ΔI DRN DRN V DRAIN Pin ...

Page 5

TYPICAL PERFORMANCE CHARACTERISTICS V vs Temperature Z 14 2mA IN 14.0 13.5 13.0 12.5 12.0 85 105 –55 –35 – TEMPERATURE (°C) 425212 G04 1000 T = –40°C A ...

Page 6

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 TYPICAL PERFORMANCE CHARACTERISTICS V vs Temperature SS 2.40 2.35 2.30 2.25 2.20 2.15 2.10 2.05 2.00 –55 –35 – 105 125 TEMPERATURE (°C) 425212 G26 V vs Temperature OS 11.0 10.8 10.6 10.4 ...

Page 7

TYPICAL PERFORMANCE CHARACTERISTICS V vs Temperature GATEH 3 – GATEH IN GATE I = 2mA 3.4 IN (MS ONLY) 3.2 3.0 2.8 2.6 2.4 2.2 2.0 –55 –35 – 105 ...

Page 8

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 TYPICAL PERFORMANCE CHARACTERISTICS I (Circuit Breaker, Sourcing) TMR vs Temperature 280 TIMER = 0μA DRN 260 240 220 200 180 –55 –35 – 105 TEMPERATURE (°C) 425212 G22 I vs ...

Page 9

TYPICAL PERFORMANCE CHARACTERISTICS I vs Temperature PGH PWRGD (MS ONLY –55 –35 – 105 125 TEMPERATURE (°C) 425212 G38 PIN FUNCTIONS (MS/MS8) V (Pin ...

Page 10

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 PIN FUNCTIONS (MS/MS8) V (Pin 5/Pin 4): Negative Supply Voltage Input. Connect EE this pin to the negative side of the power supply. GATE (Pin 6/Pin 5): N-Channel MOSFET Gate Drive Output. This pin is pulled high by ...

Page 11

BLOCK DIAGRAM – 6.15V (5.09V – – 2.925V ( (3.08V 230μA IN – 4V 5.8μA + TIMER – V 5.8μ ...

Page 12

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 OPERATION Hot Circuit Insertion When circuit boards are inserted into a live backplane, the supply bypass capacitors can draw huge transient currents from the power bus as they charge. The flow of current damages the connector pins and ...

Page 13

OPERATION Two modes of operation are possible during the time the MOSFET is first turning on, depending on the values of external components, MOSFET characteristics and nominal design current. One possibility is that the MOSFET will turn on gradually so ...

Page 14

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION SHUNT REGULATOR A fast responding shunt regulator clamps the V (VZ). Power is derived from –48RTN by an external current limiting resistor 1μF decoupling capacitor supply transients and contributes a short ...

Page 15

APPLICATIONS INFORMATION and R2 = 32.4k gives a typical operating range of 43.2V to 82.5V. The undervoltage shutdown and overvoltage recovery thresholds are then 39.2V and 74.4V. 1% divider resistors are recommended to preserve threshold accuracy. The R1-R2 divider values ...

Page 16

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION conditions are met. A high-to-low transition in the UV comparator immediately shuts down the LTC4252, pulls the MOSFET gate low and resets the latched PWRGD high. Overvoltage conditions detected by the OV compara- tor will also ...

Page 17

APPLICATIONS INFORMATION (μF) T 0.1 0. FAULT DUTY CYCLE (%) Figure 5. Circuit-Breaker Response Time 2.5% or more will eventually trip the circuit breaker and shut down the LTC4252. Figure 5 ...

Page 18

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION and eliminates current spikes at insertion. A large external gate-source capacitor is thus unnecessary for the purpose of compensating C . Instead, a smaller value (≥ 10nF) GD capacitor C is adequate. C also provides compensation ...

Page 19

APPLICATIONS INFORMATION A low impedance short on one card may influence the behavior of others sharing the same backplane. The initial glitch and backplane sag as seen in Figure 6 Trace 1, can rob charge from output capacitors on adjacent ...

Page 20

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION Approximating a linear charging rate zero, the I component in Equation (3) DRN(MAX) DRN can be approximated with 0.5 • I DRN(MAX) equation, TIMER capacitor C is given by ...

Page 21

APPLICATIONS INFORMATION 60 NTY100N10 IRF3710 IRF540S 20 IRF530S 10 IRF740 0 0 2000 4000 MOSFET C (pF) ISS Figure 7. Recommended Compensation Capacitor C vs MOSFET C C ISS As seen in Figure 6 previously, at the ...

Page 22

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION V CLEARS V IN LKO 1 2 GND – (–48RTN) – (–48V) UV/ LKO IN TIMER GATE V GATEL SS SENSE V OUT DRAIN PWRGD Figure 9. System Power-Up Timing (All ...

Page 23

APPLICATIONS INFORMATION UV CLEARS GND – (–48RTN) – (–48V) V UV/OV UVHI LKO TIMER GATE V GATEL SS SENSE V OUT DRAIN PWRGD Figure 10. Power-Up Timing with a Short Pin ...

Page 24

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION Undervoltage Timing In Figure 11 when UV pin drops below V the LTC4252 shuts down with TIMER, SS and GATE all pulling low. If current has been flowing, the SENSE pin voltage decreases to zero as ...

Page 25

APPLICATIONS INFORMATION UV/OV CLEARS V , CHECK OV CONDITION, GATE < V UVHI UV/OV OVERSHOOTS V UV/OV DROPS BELOW OVHI V OVLO UV/OV V UVHI TIMER GATE V GATEL SS SENSE DRAIN PWRGD Figure 12. ...

Page 26

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION TMRH 5.8μA TIMER DRN GATE SS V ACL V CB SENSE V OUT DRAIN PWRGD CB FAULT (14a) Momentary Circuit-Breaker Fault Figure 14. Circuit-Breaker Timing Behavior (All Waveforms Are Referenced to V the ...

Page 27

APPLICATIONS INFORMATION TIMER GATE SENSE DRAIN PWRGD Figure 15. Pushbutton Reset of LTC4252-1’s Latched Fault (All Waveforms Are Referenced to V CIRCUIT BREAKER TIMES OUT 1 2 5.8μA DRN 5.8μA TIMER V TMRL GATE SS SENSE V OUT DRAIN PWRGD ...

Page 28

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION Analog Current Limit and Fast Current Limit In Figure 17a, when SENSE exceeds V regulated by the analog current limit amplifier loop. When SENSE drops below V , GATE is allowed to pull up. In ACL ...

Page 29

APPLICATIONS INFORMATION END OF INTIAL TIMING CYCLE 12 34 567 7a V TMRH TIMER V TMRL GATE V GS(th) 58μ ACL SENSE DRAIN PWRGD (18a) Without External C Figure 18. Soft-Start Timing (All Waveforms ...

Page 30

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION –48RTN –48RTN (SHORT PIN) R1 392k 1% R2 30. 10nF –48V *FMMT493 **DIODES, INC † Circuit Breaker with Foldback Current Limit Figure 20 shows the LTC4252A in a foldback current limit application. When V ...

Page 31

APPLICATIONS INFORMATION –48RTN –48RTN (SHORT PIN) R1 392k 1% C1 10nF R2 30.1k 1% –48V *MOC207 Figure 20. Circuit Breaker with Foldback Current Limit Application –48RTN –48RTN (SHORT PIN) R1 392k 1% C1 10nF R2 30.1k 1% –48V *MOC207 **DIODES, ...

Page 32

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION –48RTN DIODE-OR CIRCUIT FOR CHANNEL A –48V A R IN2 3 × 1.8k IN SERIES 1/4W EACH C IN2 1μF FDV301N DIODE-OR CIRCUIT FOR CHANNEL B –48V B R IN3 3 × 1.8k IN SERIES 1/4W ...

Page 33

APPLICATIONS INFORMATION The internal fault latches of the LTC4252 are disabled as the TIMER pin is always held low by the SS voltage when Q2 and Q3 are in analog current limit. If both power supplies from channel A and ...

Page 34

LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ 0.889 ± 0.127 (.035 ± .005) 5.23 3.20 – 3.45 (.206) (.126 – .136) MIN 0.42 ± 0.038 0.65 (.0165 ± .0015) (.0256) TYP BSC RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS ...

Page 35

REVISION HISTORY (Revision history begins at Rev C) REV DATE DESCRIPTION C 2/11 Revised Typical Application drawings Revised Figures 19, 20, 21, 22 and 23 Replaced Shunt Regulator section in Applications Information D 3/12 Not recommended for ...

Page 36

... C1 10nF –48V **DIODES, INC RELATED PARTS PART NUMBER DESCRIPTION LT1640AH/LT1640AL Negative High Voltage Hot Swap Controllers in SO-8 LT1641-1/LT1641-2 Positive High Voltage Hot Swap Controllers in SO-8 LTC1642 Fault Protected Hot Swap Controller LTC4214 Negative Voltage Hot Swap Controller LTC4220 Dual Supply Hot Swap Controller LT4250 – ...

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