MIC2584-JBTS Micrel Inc, MIC2584-JBTS Datasheet - Page 16

• Manufacturer Part Number: MIC2584-JBTS
• Description: IC CTRLR HOT SWAP DUAL 16-TSSOP
• Manufacturer: Micrel Inc
• Type: Hot-Swap Controllerr

Specifications of MIC2584-JBTS

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: 1 V ~ 13.2 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP
• Linear Misc Type: Positive Low Voltage
• Family Name: MIC2584
• Package Type: TSSOP
• Operating Supply Voltage (min): 1V
• Operating Supply Voltage (max): 13.2V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 4.4mm
• Product Height (mm): 0.9mm
• Product Length (mm): 5mm
• Mounting: Surface Mount
• Pin Count: 16
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

MIC2584/2585
and the resulting t
approximately 2.5ms. (See "
Timer, and Sequenced Output Delays
t
GATE Capacitance Dominated Start-Up
In this case, the value of the load capacitance relative to the
GATE capacitance is small enough such that during start-up
the output current never exceeds the current limit threshold
as determined by Equation 3. The minimum value of C
that will ensure that the current limit is never exceeded is
given by the equation below:
Where C
tance (C
connected to the GATE pin of the MIC2584/85 (and MOSFET)
to ground. Once C
equation
dV
Table 1 depicts the output slew rate for various values of C
Current Limiting and Dual-Level Circuit Breaker
Many applications will require that the inrush and steady state
supply current be limited at a specific value in order to protect
critical components within the system. Connecting a sense
resistor between the VCC and SENSE pins of each channel
sets the nominal current limit value for each channel of the
MIC2584/85 and the current limit is calculated using
Equation 2.
The MIC2584/85 also features a dual-level circuit breaker
triggered via 50mV and 100mV current limit thresholds sensed
across the VCC and SENSE pins. The first level of the circuit
breaker functions as follows. For the MIC2584/85, once the
voltage sensed across these two pins exceeds 50mV on
either channel, the overcurrent timer, its duration set by
capacitor C
using a 2.5 A constant current source. If the voltage at
CFILTER reaches the overcurrent timer threshold (V
1.235V, then CFILTER immediately returns to ground as the
circuit breaker trips and both GATE outputs are immediately
shut down. For the second level, if the voltage sensed across
VCC and SENSE of either channel exceeds 100mV
(–J option) at any time, the circuit breaker trips and both
MIC2584/2585
OCSLOW
OUT
Table 1. Output Slew Rate Selection for GATE
C
dV
/dt for gate capacitance dominated start-up:
GATE
C
0.001 F
0.01 F
0.1 F
1 F
).
GATE
OUT
ISS
GATE
FILTER
) specification and the value of the capacitor
Capacitance Dominated Start-Up
to
/dt
(Min)
is the summation of the MOSFET input capaci-
determine
OCSLOW
C
, starts to ramp the voltage at CFILTER
I
GATE
GATE
GATE
I
I
GATE
LIMIT
I
GATE
is determined, use the following
needed to achieve a 12V output is
= 14 A
C
Power-On Reset, Overcurrent
LOAD
the
dV
14V/ms
1.4V/ms
0.14V/ms
0.014V/ms
OUT
output
" section to calculate
/dt
slew
TMR
GATE
GATE
rate
) of
.
16
GATE outputs shut down immediately, bypassing the
overcurrent timer period. To disable current limit and circuit
breaker operation, tie each channel’s SENSE and VCC pins
together and the CFILTER pin to ground.
Output Undervoltage Detection
The MIC2584/85 employ output undervoltage detection by
monitoring the output voltage through a resistive divider
connected at the FB pins. During turn on, while the voltage at
either FB pin is below its threshold (V
asserted low. Once both FB pin voltages cross their respec-
tive threshold (V
tor C
time period t
the /POR pin goes HIGH. If the voltage at either FB drops
below V
one timing cycle defined by t
tion
Input/Output Overvoltage Protection
The MIC2585 monitors and detects overvoltage conditions in
the event of excessive supply transients at the MIC2585
input(s)/output(s). Whenever the voltage threshold is ex-
ceeded at either OV1 or OV2 of the MIC2585, the circuit
breaker is tripped and both GATE outputs are immediately
brought low.
Power-On Reset, Overcurrent Timer, and Sequenced
Output Delays
The Power-On Reset delay, t
/POR pin to go HIGH once the lagging voltage exceeds the
power-good threshold (V
capacitor connected to CPOR sets the interval and is deter-
mined by using Equation 1 with V
The resulting equation becomes:
where the Power-On Reset threshold (V
current (I
For the MIC2584/85, a capacitor connected to CFILTER is
used to set the timer which activates the circuit breaker during
overcurrent conditions. When the voltage across either sense
resistor exceeds the slow trip current limit threshold of 50mV,
the overcurrent timer begins to charge for a period, t
determined by C
breaker is activated and both GATE outputs are immediately
pulled to ground. The following equation is used to determine
the overcurrent timer period, t
where V
I
for CFILTER is used, then t
TMR
t
OCSLOW
" for an example).
, the overcurrent timer current, is 2.5 A. If no capacitor
POR
t
POR
FB
TMR
. Once the CPOR pin voltage reaches 1.235V, the
CPOR
for more than 10 s, the /POR pin resets for at least
POR
, the overcurrent timer threshold, is 1.235V and
C
C
) are typically 1.235V and 2.5 A, respectively.
FILTER
POR
FB
elapses as pin CPOR is pulled to ground and
FILTER
), a 2.5 A current source charges capaci-
I
V
CPOR
POR
. If t
V
I
TMR
TMR
FB
OCSLOW
OCSLOW
POR
) monitored at the FB pin. A
POR
OCSLOW
0.5 C
0.5 C
(See "
POR
, is the time period for the
elapses, then the circuit
defaults to 20 s.
substituted for V
POR
.
Applications Informa-
FILTER
FB
), the /POR pin is
F
POR
( F)
) and timer
March 2005
(7)
OCSLOW
(8)
START
Micrel
.
,