Datasheet

MAX4959/MAX4960
High-Voltage OVP with Battery Switchover
6
Maxim Integrated
no blanking time for OVP, but the debounce time
applies once the IN voltage falls below V
OVLO
but
above V
UVLO
. When the voltage at IN is higher than
V
OVLO
, the CB pin does not control P1.
Correct Adapter (V
UVLO
< V
IN
< V
OVLO
)
In this case, when the adapter is plugged in, the device
goes through a 20ms (typ) debounce time and ensures
that the voltage at IN is between V
UVLO
and V
OVLO
before P1 is turned on. In this state, the CB pin controls
both P1 and P2.
Low-Power Adapter or Glitch Condition
If the adapter has the correct voltage but not enough
power (incorrect low-power adapter), the MAX4959/
MAX4960 protect pFET P1 from oscillation. When the
adapter is first plugged in, P1 is off so the voltage is cor-
rect. When P1 is turned on after the debounce time, the
low-power adapter is dragged down to below V
UVLO
.
The device waits for a 10ms blanking time to make sure
it is not a temporary glitch, and, if a fault still exists, it
latches off P1. P1 does not turn on again until the
adapter is unplugged (V
IN
< ~0.75V) and plugged in
again. This feature can work without the battery present
MAX4959
+
-
+
-
+
-
+
-
GATE2
CB
GND
UVS
OVS
V
DD
N2N1
GATE1
N
IN
V
SG
+
-
+
-
LOGIC
DIGITAL
SUPPLY
ANALOG
SUPPLY
BANDGAP
UVLO
OVLO
UVLOINT
POWER
ON
V
DD
UVLO
VREF1 = 2V
VREF2 = 0.7V
POWER-ON
RESET AND
OFF STORAGE
Functional Diagram for the MAX4959
Functional Diagrams