LTC4211IS8 Linear Technology, LTC4211IS8 Datasheet - Page 26

• Manufacturer Part Number: LTC4211IS8
• Description: IC CTRLR HOTSWAP CURR CTRL 8SOIC
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4211IS8

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: 2.5 V ~ 16.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC4211
26
12V Hot Swap Application
Figure 17 shows a 12V, 3A hot swap application circuit.
The resistor divider R1/R2 programs the undervoltage
lockout externally and allows the system to start up after
V
monitors V
above 10.54V. Transient voltage suppressor Z1 and snub-
ber network (C
the 12V applications system from ringing and voltage
spikes. R
minimize high frequency parasitic oscillations in the power
MOSFET.
AUTORETRY AFTER A FAULT
To configure the LTC4211 to automatically retry after a
fault condition, the FAULT and ON pins can be connected
to a pull-up resistor (R
CC
increases above 9.46V. The resistor divider R3/R4
G
OUT
is recommended for V
GND
RESET
and signals the RESET pin when V
X
, R
V
5V
CC
X
U
CONNECTOR
BACKPLANE
) are highly recommended to protect
(FEMALE)
GND
12V
V
AUTO
CC
U
CONNECTOR
CONNECTOR
BACKPLANE
PCB EDGE
) to the supply, as shown in
(FEMALE)
(MALE)
LONG
R
SHORT
LONG
PULL-UP
W
CONNECTOR
CC
PCB EDGE
C
10k
(MALE)
AUTO
1µF
> 10V and it can
Figure 18. LTC4211MS Autoretry Application
LONG
SHORT
LONG
Z1 = 1SMA12A OR SMAJ12A
** HIGHLY RECOMMENDED
R
(SEE NOTE)
Figure 17. 12V Hot Swap Application
AUTO
PCB CONNECTION SENSE
C
C
100pF
U
TIMER
FILTER
10nF
61.9k
Z1**
OUT
R1
R
10Ω
goes
R2
10k
R3
10Ω
X
C
100nF
C1
0.1µF
X
5
1
2
3
4
Z1 = 1SMA10A OR SMAJ10A
* OPTIONAL
2
RESET
ON
FILTER
TIMER
GND
LTC4211MS
ON
V
CC
TIMER
8
0.012Ω
R
SENSE
Figure 18. In this case, the autoretry circuitry will attempt
to restart the LTC4211 with a 50% duty cycle, as shown in
the timing diagram of Figure 19. To prevent overheating
the external MOSFET and other components during the
autoretry sequence, adding a capacitor (C
circuit introduces an RC time constant (t
the autoretry duty cycle. Equation 14 gives the autoretry
duty cycle, modified by this external time constant:
where t
tion) and t
from 0V to the ON pin threshold (1.316V).
For the values shown, the external RC time constant is set
at 1 second, the t
autoretry duty cycle drops from 50% to 2.5%.
FAULT
SENSE
GATE
3
V
Z1*
CC
FB
Autoretry Duty Cycle
SENSE
LTC4211
C
8.2nF
TIMER
10
9
8
7
6
7
GND
TIMER
Si4410DY
4
R
0.007Ω
6
GATE
SENSE
M1
RESET
OFF
R
100Ω
FB
G
= LTC4211 system timing(see TIMER func-
is a time needed to charge capacitor C
5
1
4211 F18
Si4410DY
R3
93.1k
R4
12.4k
+
Q1
TIMER
C
LOAD
NOTE:
Q1 MOUNTED TO 300mm
R
DUTY CYCLE AND Q1 T
R
DUTY CYCLE AND Q1 T
AUTO
AUTO
R1
36k
R2
15k
≈
R5
10k
= 1M YIELDS 2.5%
= 3.2M YIELDS 0.8%
+
t
delay equals 6.2ms and the
OFF
RESET
LOGIC
4211 F17
µP
C
V
5V
5A
LOAD
OUT
+ 2
t
V
12V
3A
GND
TIMER
OUT
CASE
CASE
•
2
COPPER AREA
t
= 50°C
= 37°C
TIMER
OFF
) that adjusts
•
AUTO
100
) to the
%
AUTO
(14)
4211fa