LTC4252-1CMS8 Linear Technology, LTC4252-1CMS8 Datasheet - Page 29

• Manufacturer Part Number: LTC4252-1CMS8
• Description: IC CNTRLR HOTSWAP NEGVOLT 8-MSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4252-1CMS8

• Applications: General Purpose
• Internal Switch(s): No
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• Family Name: LTC4252-1
• Package Type: MSOP
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Product Depth (mm): 3mm
• Product Height (mm): 0.86mm
• Product Length (mm): 3mm
• Mounting: Surface Mount
• Pin Count: 8
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC42521CMS8

APPLICATIO S I FOR ATIO
current begins to decline below V
loop shuts off and GATE releases at time point 8. At time
point 9, the SENSE voltage falls below V
deactivates.
Large values of C
time out as V
the circuit breaker delay. The load capacitor is unable to
achieve full charge in one GATE start-up cycle. A more
serious side effect of large C
be exceeded during soft-start into a low impedance load.
A soft-start voltage below V
breaker TIMER.
Power Limit Circuit Breaker
Figure 19 shows the LTC4252A-1 in a power limit circuit
breaking application. The SENSE pin is modulated by the
board supply voltage, V
to be the same as the low supply operating voltage,
V
operating voltage, V
power at V
selected using the ratio:
SUPPLY(MIN)
SUPPLY(MIN)
ACL
= 43V. If the goal is to have the high supply
PWRGD
(t) may exceed the V
SENSE
TIMER
DRAIN
SS
GATE
U
20 • (V
SS
can cause premature circuit breaker
SUPPLY(MAX)
V
END OF INTIAL TIMING CYCLE
(18a) Without External C
12 34 567
GS(th)
SUPPLY
, then resistors R4 and R6 are
ACL
V
V
U
TMRH
TMRL
+ V
58µA
SS
20 • V
CB
OS
Figure 18. Soft-Start Timing (All Waveforms are Referenced to V
. The zener voltage, V
)
values is SOA duration may
230µA + 8 • I
will not activate the circuit
20 • (V
OS
7a
ACL
= 71V giving the same
CB
W
(t). The current limit
+ V
CB
DRN
OS
potential during
)
8 9
CB
58µA
SS
V
V
V
and TIMER
10
ACL
CB
DRNCL
5.8µA
V
U
DRNL
11
V
IN
Z
is set
– V
GATEH
PWRGD
TIMER
SENSE
DRAIN
If R6 is 27Ω, R4 is 38.3k. The peak circuit breaker power
limit is:
when
The peak power at the fault current limit occurs at the
supply overvoltage threshold. The fault current limited
power is:
GATE
POWER
SS
V
V
POWER
R
R
SUPPLY
SUPPLY
V
END OF INTIAL TIMING CYCLE
6
4
R
12 3 4 5 6
GS(th)
LTC4252A-1/LTC4252A-2
(18b) With External C
S
=
V
V
TMRH
TMRL
V
FAULT
58µA
SUPPLY MAX
MAX
20 • V
= 0.5 • (V
•
20 • (V
LTC4252-1/LTC4252-2
⎛
⎜
⎝
230µA + 8 • I
V
V
OS
ACL
CB
=
=
ACL
=
(
1 064
•
(
7
4
+ V
POWER
V
.
–
•
SUPPLY MIN
SUPPLY(MIN)
OS
DRN
(
V
)
V
)
SUPPLY MIN
SUPPLY
8 9
•
EE
SS
20 • (V
POWER
58µA
)
V
V
V
SUPPLY MIN
(
10
ACL
CB
DRNCL
4252-1/2 F18
5.8µA
V
DRNL
CB
(
11
V
–
+ V
)
IN
+
+ V
V
OS
– V
SUPPLY MIN
)
(
Z
V
)
•
GATEH
)
SUPPLY MAX
SUPPLY(MAX)
V
•
SUPPLY MAX
)
R
R
6
4
(
⎞
⎟
⎠
(
)
(
)
) = 57V.
29
)
2
)
425212fb
(16)
(17)
(18)