MAX4919B View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX4919B Datasheet PDF : 19 Pages
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Battery Power-Up Logic with Overvoltage
and Overcurrent Protection
ADAPTER
VOLTAGE
IN
ACOK
ACOK
ONE-SHOT
25ms DEBOUNCE PERIOD
OVLO
UVLO
1.2s
ONE-SHOT
PERIOD
PWR_HOLD
STATUS
P2
OFF
OFF
ON
Figure 7. MAX4919B/MAX4920B/MAX4921B Power_Hold Waveform When Voltage at IN is Present
Note that upon VBTI falling below the 2.15V (min) thresh-
old, the internal switch remains off, irrespective of the
control signals at HP_PWR, PWR_ON, or PWR_HOLD.
Thermal Shutdown
The MAX4919B/MAX4920B/MAX4921B feature thermal
shutdown circuitry. The internal 1.8A (min) switch turns
off when the junction temperature exceeds +135°C and
immediately goes into a fault mode. The device can be
reset upon the junction temperature dropping below
+125°C. Before P2 can be turned on again, any condi-
tion that is attempting to turn it on must be first removed,
i.e., the one-shot (from IN or HP_PWR) must be complet-
ed, and PWR_ON and PWR_HOLD must be low. If the
three conditions are satisfied, P2 turns on again only if
either IN or PWR_HOLD is cycled OFF and ON.
Applications Information
MOSFET Configuration
The MAX4919B/MAX4920B/MAX4921B can drive either a
single n-channel or back-to-back n-channel MOSFET
(Figure 10). The back-to-back configuration will have
almost zero reverse current when the adapter is not pre-
sent or when the adapter voltage is below the undervolt-
age lockout threshold.
If reverse-current leakage is not a concern, a single
n-channel MOSFET can be used. This approach has
half the loss of the back-to-back configuration when
used with similar MOSFET types and is a lower cost
solution. Note that if the input is actually pulled low, the
output will be pulled low as well due to the parasitic
body diode in the MOSFET. If this is a concern, then
use the back-to-back configuration.
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