MAX5923EUP+ Maxim Integrated Products, MAX5923EUP+ Datasheet - Page 9

• Manufacturer Part Number: MAX5923EUP+
• Description: IC HOT-SWAP SWITCH +60V 20-TSSOP
• Manufacturer: Maxim Integrated Products
• Series: Simple Swapper™r
• Type: Hot-Swap Switchr

Specifications of MAX5923EUP+

• Applications: General Purpose
• Internal Switch(s): Yes
• Current Limit: 800mA
• Voltage - Supply: 16 V ~ 60 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Product: Controllers & Switches
• Supply Voltage (max): 60 V
• Supply Voltage (min): 16 V
• Power Dissipation: 879 mW
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Supply Current: 1 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

VDIG is the input supply for the internal logic circuitry.
The logic input thresholds of EN, LATCH, and ZC_EN
are CMOS compatible and are determined by the volt-
age at VDIG, which can range from 1.65V to 5.5V. The
POK and FAULT outputs are open-drain. VDIG and all
logic inputs and outputs are referenced to DGND.
DGND is not connected to AGND_S internally and must
be connected externally at a single point in the system
to AGND_S. The maximum allowable difference in the
voltage between DGND and AGND is ±4V.
EN is a logic input to enable MAX5923. Bringing EN low
halts all operations and turns off the internal power
MOSFET. When EN is high and the input voltage is
above the UVLO threshold, the MAX5923 begins oper-
ating. Enable is also used to unlatch the part after a
latched fault condition. This is done by toggling EN low
and high again after a fault condition.
The MAX5923 provides a sophisticated overcurrent pro-
tection circuitry to ensure the robust operation under out-
put current transient and current-fault conditions. The
current protection circuitry employs a Constant Current
Limit, a Current Foldback, and an Overcurrent Timeout.
The device monitors the voltage drop, V
V
The MAX5923 monitors V
lates the current through the power MOSFET as neces-
sary to keep V
voltage (V
programmed by the current-sense resistor, R
connected from IN to DRAIN (I
Figure 1. Setting Undervoltage Lockout with an External
Resistive Divider
IN
- V
DRAIN
ILIM
) in order to determine the load current.
V
IN
R1
R2
= 212mV). The load-current limit, I
= 16V TO 60V
SENSE
_______________________________________________________________________________________
+60V Simple Swapper Hot-Swap Switch
(max) to the current-limit sense
UVLO
Overcurrent Protection
SENSE
MAX5923
AGND
Constant Current Limit
IN
at all times and regu-
LIM
= V
SENSE
Digital Logic
Enable (EN)
ILIM
(V
/R
SENSE
SENSE
SENSE
LIM
, is
=
).
,
When the load current is less than I
fully on. When the load is trying to draw more than I
the OUT pin works like a constant current source, limit-
ing the output current to I
I
limit fault is generated and the power MOSFET is
turned off (see the Overcurrent Timeout and Fault
Management section).
While in current-limit condition, the voltage at the OUT pin
drops. As the load resistance reduces (more loading), the
output voltage reduces accordingly to maintain a con-
stant load current. The power dissipation in the power
MOSFET is (V
drops lower, more power is dissipated across the power
MOSFET. To reduce this power dissipation, the MAX5923
offers a current foldback feature where it linearly reduces
the V
limit foldback voltage (V
trates this current foldback limit behavior.
The MAX5923 keeps track of the time it is in current limit.
An internal digital counter begins incrementing its count
at 1count/ms when V
or V
to zero if the current falls back below the current limit.
When the cumulative count reaches 60, an overcurrent
fault is generated. After an overcurrent fault condition, the
switch is turned off and the FAULT signal goes low. This
overcurrent timeout enables the MAX5923 to operate in a
periodic overcurrent condition without causing a fault.
See Figure 3 for an example of periodic overcurrent con-
dition without causing a fault.
Figure 2. Current Foldback Characteristic
LIM
V
ILM
ILIM
V
for greater than the current-limit timeout, a current-
ILIM
ILM
/3
foldback in foldback mode). The counter is reset
value when V
DRAIN
V
FBSTART
(2V)
- V
SENSE
OUT
OUT
FBSTOP
) × I
drops below the OUT current-
LIM
exceeds its limit (either V
V
FBSTOP
(18V)
LIM
. If I
= 18V). Figure 2 illus-
. As the output voltage
Overcurrent Timeout
OUT
LIM
Current Foldback
, the MOSFET is
is greater than
V
OUT
(V)
LIM
ILIM
9
,