MAX1906VEEE Maxim Integrated, MAX1906VEEE Datasheet - Page 10

• Manufacturer Part Number: MAX1906VEEE
• Description: Battery Management
• Manufacturer: Maxim Integrated
• Series: MAX1906r

If any cell voltage exceeds the overvoltage threshold,
the MAX1906 stops sampling and monitors the cell volt-
age continuously. If the overvoltage condition persists
for more than 2.1s, the device turns on an internal SCR
and also drives the DRV pin high. The internal SCR or
the external MOSFET sinks sufficient current to blow the
three-terminal protection fuse and permanently open
the battery pack’s charge path. See the overvoltage
protection flowchart in Figure 8. Also see the Fuse
Drive Options section for discussion on current capabil-
ity for both the internal SCR and external MOSFET.
The MAX1906 remains in overvoltage mode until the
cell voltage drops to 90% of the overvoltage threshold
(V
Li+ Battery-Pack Protector with
Integrated Fuse Driver
Figure 8. Overvoltage Protection
10
REL
NO
______________________________________________________________________________________
) and the rest of cells are below the overvoltage
ALL CELLS CHECKED?
WAIT
2.56s
YES
Protection Features
Overvoltage Detection
NO
NO
NO
B_P > V
CELL CONTINUOUSLY
TIMER AND MONITOR
REST B_P < V
B_P < V
AND TIMER = 2.1s?
STOP SAMPLING
SAMPLE MODE
AND START 2.1s
B_P > V
OV_TH
SCR LATCHED
SAMPLE B_P
YES
YES
YES
DRV = H
DRV = L
REL
CONTINUOUSLY
OV_TH
AND THE
OV_TH
?
?
threshold. The DRV pin then goes low, which turns off
an external MOSFET. The internal SCR does not
unlatch until power is removed.
The MAX1906 tests for disconnected voltage sense pins
each time it exits the standby or test mode. To check for
a disconnection, the MAX1906 applies a 10µA current
source to each B_P pin. A disconnected pin is detected
if the B_P pin under test falls to within 1.2V of the cell’s
negative terminal. The DISCON pin is then pulled low.
This condition persists while the MAX1906 is in normal
operating mode, and resets only when the MAX1906
enters the standby or test mode. See Figure 9 for the
disconnected pin detection flowchart.
Figure 9. Disconnected Pin Description
NO
EXIT FROM STANDBY MODE OR TEST MODE
IS B_P AT LEAST 1.2V ABOVE
CHECK DISCONNECTION
NEGATIVE TERMINAL
ALL PINS CHECKED?
SAMPLE MODE
YES
YES
DISCON = H
OF B_P PIN
Disconnected Pin Detection
NO
DISCON = L