MAX17085BETL+ Maxim Integrated Products, MAX17085BETL+ Datasheet - Page 24

• Manufacturer Part Number: MAX17085BETL+
• Description: Battery Management Dual Main Step-Down Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX17085BETL+

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Integrated Charger, Dual Main Step-Down
Controllers, and Dual LDO Regulators
Table 4. Charger Operating Mode Truth Table
Note 5: Adapter is present when V
When the adapter voltage is removed and the adapter
is absent, the charger is disabled and PDSL is pulled to
GND. N3 and Q1a turn off, and Q1b turns on to supply
power to the system from the battery.
Table 4 defines the MAX17085B charger operating conditions.
The MAX17085B employs a synchronous step-down
DC-DC converter with an n-channel high-side MOSFET
switch and an n-channel low-side synchronous rectifier.
The charger features a controlled inductor current ripple
architecture, current-mode control scheme with cycle-
by-cycle current limit. The controller’s off-time (t
adjusted to keep the high-side MOSFET junction tem-
perature constant. In this way, the controller switches
faster when the high-side MOSFET has available thermal
capacity. This allows the inductor current ripple and
the output voltage ripple to decrease so that smaller
and cheaper components can be used. The controller
can also operate in discontinuous conduction mode for
improved light-load efficiency.
24
< UVLO
< UVLO
< UVLO
> UVLO
> UVLO
> UVLO
> UVLO
DCIN
X
X
_____________________________________________________________________________________
falling.
ADAPTER
PRESENT
(NOTE 5)
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
> OCP threshold
< OCP threshold
> OCP threshold
< OCP threshold
< OCP threshold
V
CSSP
CURRENT
INPUT
Operating Conditions
X
X
X
X
- V
DCIN
CSSN
- V
Charger SMPS
CSIN
< ACOV threshold
V
V
V
V
V
V
V
ACIN
ACINOK
ACIN
ACINOK
ACIN
ACINOK
ACIN
> 420mV with V
ACIN
> V
< V
< V
< V
and
and
and
X
X
X
X
OFF
< V
< V
< V
ACINOV
ACINOV
ACINOV
ACINOV
) is
ACIN
ACIN
ACIN
DCIN
shutdown
shutdown
threshold
threshold
The operation of the DC-to-DC controller is determined
by the following five comparators as shown in the func-
tional diagram in Figures 2 and 4:
U The IMIN comparator triggers a pulse in discontinu-
U The CCMP comparator is used for current-mode
U The IMAX comparator provides a secondary cycle-
< ISET
> ISET
ISET
< 1V
> 1V
rising, and absent when V
X
X
X
X
X
ous mode when the accumulated error is too high.
IMIN compares the control signal (LVC) against
5mV (typ) (referred at V
less than 5mV, DHC and DLC are both forced low.
Indirectly, IMIN sets the peak inductor current in dis-
continuous mode.
regulation in continuous conduction mode. CCMP
compares LVC against the inductor current. The high-
side MOSFET on-time is terminated when the CSI
voltage is higher than LVC.
by-cycle current limit. IMAX compares CSI to the
current limit programmed at ISET. The high-side
MOSFET on-time is terminated when the current-
sense signal exceeds the programmed limit. A new
V
V
V
PDSL
GND
GND
GND
GND
GND
GND
+ 8V
+ 8V
+ 8V
DCIN
DCIN
DCIN
(ISET control)
CHARGER
STATE
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
DCIN
CSIP
- V
CSIN
- V
IINP
OFF
ON
ON
ON
ON
ON
ON
ON
ON
CSIN)
< 120mV with V
Adapter
overvoltage fault
Adapter
overcurrent fault
ISET shutdown
. When LVC is
COMMENTS
—
—
—
—
—
—
DCIN