DS2731K Maxim Integrated, DS2731K Datasheet - Page 3

• Manufacturer Part Number: DS2731K
• Description: Power Management IC Development Tools
• Manufacturer: Maxim Integrated
• Series: DS2731r

The charger circuitry can be disabled by removing the
0Ω resistor on JP2. The board is shipped with the 0Ω
resistor in place (charger enabled).
Similarly, the buck regulator can be disabled by pulling
ENS high through a 0Ω resistor on JP1. The board is
shipped without the 0Ω resistor in place (buck regulator
enabled).
Current is regulated based on the voltage drop across
an external 50mΩ sense resistor and an internal feed-
back circuit. The CC charge rate, I
RSET pin. It can be calculated by the following formula:
where R is the value of the resistor connected to RSET.
The charge current can range from 0.5A to 1.5A. The
board is shipped with I
Figure 2. Li+ Charge Cycle
Charger/Buck Regulator Enables
_______________________________________________________________________________________
I
CHARGE
Setting Charge Parameters
10% x I
CHARGE
Board Configuration
I
CHARGE
CHARGE
= 2500/R
I
= 1.00A.
Constant Current (CC)
PRECHARGE
CHARGE
BEGIN
MODE
CHARGE
( ENS , ENC)
, is set at the
CONSTANT-CURRENT
MODE
V
When the battery voltage reaches the CV output thresh-
old, CV mode is entered. The charger stops regulating
current and begins regulating voltage. The MARGIN pin
sets the CV threshold according to the following formula:
where R2 is the resistor between STMR and MARGIN,
and R1 is the resistor between MARGIN and ground.
Voltage regulation can be set from +3.8V to +4.6V. The
board is shipped with V
The charger has a safety timer that sets the maximum
length of time for a charge cycle. It is programmable
from 1hr to 10hr.
Timing Equation:
The board is shipped with t = 10,936s = 3.04hr. If this
timer expires and the battery fails to reach the termina-
tion current, the charger enters the fault state and is
latched off. Charging does not continue until either the
DS2731 Evaluation Kit
CONSTANT-VOLTAGE
I
V
0.1647 x R
PK
MODE
CHARGE TERMINATION
(CV set point) = 4.97V x R1/(R2 + R1)
STMR
CHARGE
END
PK
= t(s); R
V
V
V
5% x I
t
PK
MIN
= +4.21V.
CHARGE
Constant Voltage (CV)
STMR
= R1 + R2
SMTR
3