MAX4789EUK-T-MAX4792EUS-T-MAX4794ETT Fast Delivery |IC PHOENIX CO.,LIMITED

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MAX4789EUK-T-MAX4792EUS-T-MAX4794ETT
200mA/250mA/300mA Current-Limit Switches
General Description
The MAX4789–MAX4794 family of switches feature
internal current limiting to prevent damage to host
devices due to faulty load conditions. These analog
switches have a low 0.2Ωon-resistance and operate
from 2.3V to 5.5V input voltage range. They are avail-
able with guaranteed 200mA, 250mA, and 300mA cur-
rent limits, making them ideal for SDIO and other load
switching applications.
When the switch is on and a load is connected to the
port, a guaranteed blanking time of 14ms ensures that
the transient voltages settle down. If after this blanking
time the load current is greater than the current limit,
the MAX4789, MAX4791, and MAX4793 enter a latch-
off state where the switch is turned off and FLAGis
issued to the microprocessor. The switch can be turned
on again by cycling the power or the ON pin.
The MAX4790, MAX4792, and MAX4794 have an
autoretry feature where the switch turns off after the
blanking time and then continuously checks to see if
the overload condition is present. The switch remains
on after the overload condition disappears.
The MAX4789–MAX4794 are available in 6-pin thin QFN
and tiny space-saving 4-pin SOT143 packages. The
MAX4789/MAX4791/MAX4793 are also available in a
tiny 5-pin SOT23 package. For lower current current-limit-
ing switches, refer to the MAX4785–MAX4788 data sheet.
Applications
PDAs and Palmtop Devices
Cell Phones
GPS Systems
Hand-Held Devices
SDIO
FeaturesGuaranteed Current Limit: 200mA, 250mA, 300mAThermal-Shutdown Protection Reverse Current Protection0.2ΩOn-Resistance14ms Guaranteed Blanking TimeFLAGFunction (MAX4789/MAX4791/MAX4793)80µA Supply Current8µA Latch-Off Current
(MAX4789/MAX4791/MAX4793)0.01µA Shutdown Current2.3V to 5.5V Supply RangeUndervoltage LockoutFast Current-Limit Response Time (5µs)Tiny QFN and SOT23/SOT143 Packages
MAX4789–MAX4794
200mA/250mA/300mA Current-Limit Switches
Ordering Information
Typical Operating Circuit
19-2663; Rev 1; 8/03
*EP = Exposed pad.
Ordering Information continued at end of data sheet.
Selector Guide appears at end of data sheet.
Pin Configurations
MAX4789–MAX4794
200mA/250mA/300mA Current-Limit Switches
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, ON, FLAG, OUT to GND.....................................-0.3V to +6V
OUT Short Circuit to GND.................................Internally Limited
Continuous Power Dissipation (TA= +70°C)
4-Pin SOT143 (derate 4.0mW/°C above +70°C)..........320mW
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
6-Pin Thin QFN (derate 24.4mW/°C above +70°C)...1951.2mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
MAX4789–MAX4794
200mA/250mA/300mA Current-Limit Switches
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4789 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
SUPPLY CURRENT
vs. TEMPERATURE
MAX4789 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (3510-15
LATCH-OFF CURRENT
vs. TEMPERATURE
MAX4789 toc03
TEMPERATURE (°C)
LATCH-OFF (3510-15
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4789 toc04
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (nA)3510-15
SHUTDOWN LEAKAGE CURRENT
vs. TEMPERATURE
MAX4789 toc05
TEMPERATURE (°C)
SHUTDOWN LEAKAGE CURRENT (nA)3510-15
LATCH-OFF LEAKAGE CURRENT
vs. TEMPERATURE
MAX4789 toc06
TEMPERATURE (°C)
LATCH-OFF LEAKAGE CURRENT (nA)3510-15
Typical Operating Characteristics
(VIN= 3.3V, TA= +25°C, unless otherwise noted.)
Note 1:All parts are 100% tested at +25°C. Limits across the full temperature range are guaranteed by design and correlation.
Note 2:Latch-off current does not include the current flowing into FLAG.
Note 3:The on time is defined as the time taken for the current through the switch to go from 0mA to full load. The off-time is defined
as the time taken for the current through the switch to go from full load to 0mA.
Note 4:Retry time is typically 7 times the blanking time.
ELECTRICAL CHARACTERISTICS (continued)
(VIN= 2.3V to 5.5V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VIN= 3.3V, TA= +25°C.) (Note 1)
MAX4789–MAX4794
200mA/250mA/300mA Current-Limit Switches
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
MAX4789 toc07
TEMPERATURE (°C)
NORMALIZED R3510-15
OUTPUT CURRENT
vs. OUTPUT VOLTAGE
MAX4789 toc08
VIN - VOUT (V)
OUTPUT CURRENT (mA)
SWITCH TURN-ON/OFF TIMES
vs. TEMPERATURE
MAX4789 toc09
TEMPERATURE (°C)
TURN-ON/OFF TIMES (3510-15
FLAG-BLANKING TIMEOUT
vs. TEMPERATURE
MAX4789 toc10
TEMPERATURE (°C)
FLAG-BLANKING TIME (ms)3510-15
CURRENT-LIMIT RESPONSE
MAX4789 toc11
40µs/div
VIN
2V/div
VON
2V/div
IOUT
100mA/div
CURRENT-LIMIT RESPONSE
MAX4789 toc12
20µs/div
VIN = VON
1V/div
IOUT
100mA/div
Typical Operating Characteristics (continued)
(VIN= 3.3V, TA= +25°C, unless otherwise noted.)
MAX4789–MAX4794
200mA/250mA/300mA Current-Limit Switches
Pin Description
Typical Operating Characteristics (continued)
(VIN= 3.3V, TA= +25°C, unless otherwise noted.)
FLAG-BLANKING RESPONSE
MAX4789 toc16
4ms/div
FLAG
2V/div
IOUT
100mA/div
VIN
2V/div
VON
2V/div
SWITCH TURN-OFF TIME RESPONSE
MAX4789 toc15
200ns/div
VON
2V/div
IOUT
10mA/div
MAX4789–MAX4794
Detailed Description
The MAX4789–MAX4794 are forward/reverse current-
limited switches that operate from a 2.3V to 5.5V input
voltage range and guarantee a 200mA, 250mA, and
300mA minimum current-limit threshold for different
options. The voltage drop across an internal sense
resistor is compared to two reference voltages to indi-
cate a forward or reverse current-limit fault. When the
load current exceeds the preset current limit for greater
than the fault-blanking time, the switch opens.
The MAX4790, MAX4792, and MAX4794 have an
autoretry function that turns on the switch again after an
internal retry time expires. If the faulty load condition is
still present after the blanking time, the switch turns off
again and the cycle is repeated. If the faulty load con-
dition is not present, the switch remains on.
The MAX4789, MAX4791, and MAX4793 do not have
the autoretry option and the switch remains in latch-off
mode until the ON pin or the input power is cycled from
high to low and then high again.
The undervoltage lockout (UVLO) circuit prevents erro-
neous switch operation when the input voltage goes too
low during startup conditions.
Reverse Current Protection
The MAX4789–MAX4794 limit the reverse current (VOUT
to VIN) from exceeding the maximum IREVvalue. The
switch is shut off and FLAGis asserted (MAX4789/
MAX4791/MAX4793) if the reverse current-limit condition
persists for more than the blanking time. This feature pre-
vents excessive reverse currents from flowing through the
device.
Switch-On/Off Control
Toggle ON high to enable the current-limited switches.
The switches are continuously on, only if VINexceeds the
UVLO threshold (typically 2V) and there is no fault. When
a forward/reverse current fault is present or the die
exceeds the thermal-shutdown temperature of +150°C,
OUT is internally disconnected from IN and the supply
current decreases to 8µA (latch off). The switch is now
operating in one of its off states. The switch-off state also
occurs when driving ON low, thus reducing the supply
current (shutdown) to 0.01µA. Table 1 illustrates the
ON/OFF state of the MAX4789–MAX4794 current-limit
switches.
FLAGIndicator
The MAX4789, MAX4791, and MAX4793 feature a
latched fault output, FLAG. Whenever a fault is activat-
ed, it latches FLAGoutput low and also turns the switch
200mA/250mA/300mA Current-Limit Switches
Figure 1. Functional Diagram
off. FLAGis an open-drain output transistor and requires
an external pullup resistor from FLAGto IN. During shut-
down (ON is low), the pulldown on FLAGoutput is
released in order to limit power dissipation. FLAGgoes
low when any of the following conditions occur:The die temperature exceeds the thermal-shutdown
temperature limit of +150°C.The device is in current limit for more than the fault-
blanking period.VINis below UVLO threshold.
Autoretry (MAX4790/MAX4792/MAX4794)
When the forward or reverse current-limit threshold is
exceeded, tBLANKtimer begins counting (Figure 2).
The timer resets if the overcurrent condition disappears
before tBLANKhas elapsed. A retry time delay, tRETRY,
is started immediately after tBLANKhas elapsed and
during that time, the switch is latched off. At the end of
tRETRY, the switch is turned on again. If the fault still
exists, the cycle is repeated. If the fault has been
removed, the switch stays on.
The autoretry feature saves system power in the case
of an overcurrent or short-circuit condition. During
tBLANK, when the switch is on, the supply current is at
the current limit. During tRETRY, when the switch is off,
the current through the switch is zero. Instead of
observing the full load current, the switch sees the
equivalent load current times duty cycle or ISUPPLY=
ILOAD✕tBLANK/(tBLANK+ tRETRY). With a typical
tBLANK= 37ms and typical tRETRY= 259ms, the duty
cycle is 12%, which results in an 88% power savings
over the switch being on the entire time. The duty cycle
is consistent across the process and devices.
Latch Off (MAX4789/MAX4791/MAX4793)
When the forward or reverse current-limit threshold is
exceeded, tBLANKtimer begins counting. The timer
resets if the overcurrent condition disappears before
tBLANKhas elapsed. The switch is shut off if the over-
current condition continues up to the end of the blank-
ing time. Reset the switch by either toggling ON (Figure
3a) or cycling the input voltage below UVLO, typically
2V (Figure 3b).
Fault Blanking
The MAX4789–MAX4794 feature 14ms (min) fault blank-
ing. Fault blanking allows current-limit faults, including
momentary short-circuit faults that occur when hot
swapping a capacitive load, and also ensures that no
fault is issued during power-up. When a load transient
causes the device to enter current limit, an internal
counter starts. If the load-transient fault persists beyond
the fault-blanking timeout, the MAX4789/MAX4791/
MAX4793 FLAGasserts low. Load-transient faults less
than tBLANKdo not cause a FLAGoutput assertion. Only
current-limit faults are blanked.
A thermal fault and input voltage drops below the
UVLO threshold cause FLAGto assert immediately and
do not wait for the blanking time.
Thermal Shutdown
The MAX4789–MAX4794 have a thermal shutdown fea-
ture to protect the devices from overheating. The switch
turns off and FLAGgoes low immediately (no fault blank-
ing) when the junction temperature exceeds +150°C.
The switch turns back on when the device temperature
drops approximately 15°C.
MAX4789–MAX4794
200mA/250mA/300mA Current-Limit Switches

Partno	Mfg	Dc	Qty	Available	Descript
MAX4789EUK-T \|MAX4789EUKT	MAXIM	N/a	790	avai	200mA/250mA/300mA Current-Limit Switches
MAX4792EUS-T \|MAX4792EUST	MAXIM	N/a	7688	avai	200mA/250mA/300mA Current-Limit Switches
MAX4794ETT	MAXIM	N/a	1000	avai	200mA/250mA/300mA Current-Limit Switches