DS2711E+ Maxim Integrated Products, DS2711E+ Datasheet - Page 11

• Manufacturer Part Number: DS2711E+
• Description: IC NIMH CHARGER 16TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS2711E+

• Function: Charge Management
• Battery Type: Nickel Metal Hydride (NiMH)
• Voltage - Supply: 4 V ~ 5.5 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP
• Operating Supply Voltage: 5.5 V
• Supply Current: 250 uA
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: - 20 C
• Charge Safety Timers: Yes
• Mounting Style: SMD/SMT
• Temperature Monitoring: Yes
• Uvlo Start Threshold: 3.5 V
• Uvlo Stop Threshold: 40 mV
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Charge Timer
The charge timer monitors the duration of charge in fast and top-off charge phases, and is reset at the beginning of
each phase. The time-out period is set with an external resistor connected from the TMR pin to V
be selected to support fast-charge time-out periods of 0.5 to 10 hours and top-off charge time-out periods of 0.25 to
5 hours. If the timer expires in fast-charge, the timer count is reset and charging proceeds to the top-off charge
phase. The top-off time-out period is half of the fast charge time-out period. If the timer expires in top-off, charging
proceeds to the maintenance phase. The programmed charge time approximately follows the equation:
Suspend
Suspension of charge activity is possible by floating the TMR pin. The CC1 and CC2 outputs become high-Z and
the charge timer stops. The state machine and all timers are reset to their presence test conditions.
Temperature Sense
Connecting an external 10kΩ NTC thermistor between THM1 or THM2 (THMx) and V
between V
locate the thermistor close to the body of the battery cell so THM1 monitors the temperature of cell-1 and THM2
monitors the temperature of cell-2. Alternatively, the thermistor can sense ambient temperature by locating it away
from the cells. THM1 and THM2 can be connected together to sense temperature using a single thermistor and
bias resistor. The temperature qualification function can be defeated by connecting THM1 and THM2 to a single
resistor-divider supplying a voltage between the Thermistor-Min and Thermistor-Max threshold voltages. Several
recommended 10kΩ thermistors are shown in Table 2.
Min, Max Temperature Compare
The voltage thresholds of the THMx inputs (VTHM-MIN, VTHM-MAX) are set to allow fast charging to start if 0°C <
T
voltage on THMx reaches VTHM-STOP, fast charging stops and the maintenance phase begins.
Table 2. THM1, THM2 THRESHOLDS
Figure 7. CELL VOLTAGE SENSE POINTS
A
< 45°C when using the recommended 10kΩ bias and 10kΩ thermistor. If fast charging is in progress, and the
THRESHOLD
STOP
THM
MAX
MIN
DD
and THMx allows the DS2711 to sense temperature. To sense the temperature of the battery cells,
OF V
RATIO
0.73
0.33
0.29
DD
t = 1.5 x R / 1000
THERMISTOR
RESISTANCE
27.04k
4.925k
4.085k
(Ω)
11 of 15
(time in minutes)
103AT-2
Semitec
45°C
50°C
0°C
TEMPERATURE (°C)
197-103LAG-A01
173-103LAF-301
Fenwal
42°C
47°C
SS
4°C
, and a 10kΩ bias resistor
SS
. Resistors can