MAX5931AEEP+ Maxim Integrated Products, MAX5931AEEP+ Datasheet - Page 18

• Manufacturer Part Number: MAX5931AEEP+
• Description: IC HOT-SWAP CTRLR TRPL 20-QSOP
• Manufacturer: Maxim Integrated Products
• Type: Hot-Swap Controllerr

Specifications of MAX5931AEEP+

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: 1 V ~ 15 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-SSOP (0.154", 3.91mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The startup period (t
50ms. The adjustable startup period feature allows sys-
tems to be customized for MOSFET gate capacitance
and board capacitance (C
adjusted with a resistor connected from TIM to GND
(R
startup period has a default value of 9ms when TIM is left
unconnected. Calculate R
where t
There are two ways of completing the startup
sequence. Case A describes a startup sequence that
slowly turns on the MOSFETs by limiting the gate
charge. Case B uses the current-limiting feature and
turns on the MOSFETs as fast as possible while still
preventing a high inrush current. The output voltage
ramp-up time (t
two timings, case A and case B. Set the startup timer
(t
time for the output voltage to settle.
Case A: Slow Turn-On (Without Current Limit)
There are two ways to turn on the MOSFETs without
reaching the fast-comparator current limit:
• If the board capacitance (C
• If the gate capacitance is high, the MOSFETs turn
In both cases, the turn-on time is determined only by
the charge required to enhance the MOSFET. The
small 100µA gate-charging current effectively limits
the output voltage dV/dt. Connecting an external
capacitor between GATE and GND extends the turn-
on time. The time required to charge/discharge a
MOSFET is as follows:
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
Table 7. Component Manufacturers
18
Sense Resistors
MOSFETs
START
TIM
inrush current is low.
on slowly.
______________________________________________________________________________________
). R
COMPONENT
START
) to be longer than t
TIM
must be between 4kΩ and 500kΩ. The
is the desired startup period.
ON
R
) is determined by the longer of the
TIM
START
Setting the Startup Period, R
=
128
TIM
BOARD
) is adjustable from 0.4ms to
Vishay
IRC, Inc.
Fairchild Semiconductor
International Rectifier
ON Semiconductor
t
START
with the following equation:
×
ON
800
Startup Sequence
). The startup period is
to guarantee enough
BOARD
MANUFACTURER
pF
) is small, the
TIM
where:
C
(Figure 9),
ΔV
Q
I
In this case, the inrush current depends on the MOSFET
gate-to-drain capacitance (C
capacitance from GATE to GND (C
load current (I
Example: Charging and discharging times using the
Fairchild FDB7030L MOSFET
If V
V
data sheet specifies that the FDB7030L has approxi-
mately 60nC of gate charge and C
MAX5930A/MAX5931A/MAX5931B have a 100µA gate
charging current and a 3mA/50mA normal/strong dis-
charging current. C
draw any current during the startup period. With no gate
capacitor, the inrush current, charge, and discharge
times are:
GATE
DRIVE
t
GATE
GATE
DISCHARGE NORMAL
GATE
t
DISCHARGE STRONG
402-563-6325
361-992-7900
888-522-5372
310-322-3331
602-244-6600
IN1
PHONE
is the gate-charging/discharging current.
I
INRUSH
), therefore ΔV
= 5V then GATE1 charges up to 10.4V (V
is the MOSFET total gate charge,
is the external gate to ground capacitance
I
t
INRUSH
is the change in gate charge,
CHARGE
(
t
LOAD
(
=
=
=
C
C
=
600
RSS
GATE
) present during the startup period.
0
BOARD
C
6
pF
×
)
GATE
BOARD
μ
)
www.vishay.com
www.irctt.com
www.fairchildsemi.com
www.irf.com
www.onsemi.com
+
=
F
=
10 4
×
+
0
C
100
Δ
0
.
0
×
GATE
I
V
= 6µF and the load does not
GATE
= 10.4V. The manufacturer’s
V
×
GATE
×
μ
10 4
A
+
100
RSS
10 4
.
3
60
mA
×
50
V
.
μ
+
) plus any additional
WEBSITE
nC
V
mA
I
A
+
GATE
Q
GATE
RSS
+
+
GATE
60
=
60
0
nC
+
0 6
), and on any
= 600pF. The
nC
=
.
I
LOAD
ms
=
1
A
=
0 02
1 2
.
.
IN1
μ
ms
s
+