The autoretry feature saves system power in the case of

when the switch is on, the supply current is at the cur-

rent through the switch is zero. Instead of observing the

full load current, the switch sees the equivalent load

6%, which results in a 94% power savings over the

switch being on the entire time. The duty cycle is con-

sistent across the process and devices.

Latch Off (MAX4772)

When the forward or reverse current-limit threshold is

resets if the overcurrent condition disappears before

asserts if the overcurrent condition continues up to the

end of the blanking time. Reset the switch by either tog-

gling ON (Figure 5) or cycling the input voltage (Figure 5).

Fault Blanking

The MAX4772/MAX4773 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, FLAG asserts low. Load-tran-

put assertion. Only current-limit faults are blanked.

A thermal fault causes FLAG to assert immediately and

does not wait for the blanking time.

Thermal Shutdown

The MAX4772/MAX4773 have a thermal-shutdown fea-

ture to protect the devices from overheating. The switch

turns off and FLAG goes low immediately (no fault

blanking) when the junction temperature exceeds

+150°C. The switch with autoretry turns back on when

the device temperature drops approximately 15°C. The

switch with the latch off requires ON cycling.

Applications Information

Input Capacitor

To limit the input-voltage drop during momentary output

short-circuit conditions, connect a capacitor from IN to

GND. A 0.1µF ceramic capacitor is adequate for most

applications; however, higher capacitor values further

200mA/500mA Selectable

Current-Limit Switches

8

_______________________________________________________________________________________

Figure 5. MAX4773 Latch-Off Fault Blanking

LOAD

CURRENT

SWITCH

STATUS

ON PIN

VOLTAGE

OFF

ON

(a)

(b)

LOAD

CURRENT

SWITCH

STATUS

IN PIN

VOLTAGE

OFF

ON

FLAG PIN

STATUS

FLAG PIN

STATUS

Figure 4. MAX4773 Autoretry Fault-Blanking Diagram

LOAD

CURRENT

SWITCH

STATUS

FLAG PIN

STATUS

OFF

ON

CURRENT

LIMIT

SHORT

CONDITION

REMOVED