DS2715 Ver la hoja de datos (PDF) - Dallas Semiconductor -> Maxim Integrated
Número de pieza
componentes Descripción
Lista de partido
DS2715 Datasheet PDF : 12 Pages
| |||
DS2715: NiMH Cell Pack Charge Controller
TEMPERATURE SENSE
Accurate temperature sensing is needed to determine end of charge by dT/dt and to detect over temperature fault
conditions. Connecting an external 10kW NTC thermistor between THM and VSS, and a 10kW bias resistor between
Div and THM allows the DS2715 to sense temperature. To sense the temperature of the cell pack, locate the
thermistor close to the body of a cell, preferably in the middle of the cell pack. Several recommended 10kW
thermistors are shown in Table 2.
Min, Max Temperature Compare
The voltage thresholds of the THM input (VTHM-MIN, VTHM-MAX) are set to allow charging to start if 0°C < TCELL < 45°C
when using the recommended 10kW bias and 10kW thermistor. If pre-charging is in progress, and the voltage on
THM reaches VTHM-STOP, pre-charging stops and a fault condition is generated. If the voltage on THM reaches VTHM-
STOP during fast charge or top-off, charging stops and the DS2715 enters the DONE state. Fast charging will
complete normally and top-off will begin if the voltage change on THM exceeds TTERM ºC per minute (dT/dt charge
termination).
Table 2. THM1, THM2 THRESHOLDS
THM
THRESHOLD
MIN
MAX
STOP
RATIO
OF VCBIAS
THERMISTOR
RESISTANCE
(W)
0.73
27.04k
0.33
4.925k
0.29
4.085k
Semitec
103AT-2
0°C
45°C
50°C
TEMPERATURE (°C)
Fenwal
197-103LAG-A01
173-103LAF-301
4°C
42°C
47°C
Used with a 10k resistor the Semitec 103AT-2 provides about 0.9% full scale per degree sensitivity. This linearity is
shown in the curve in Figure 4. The left axis is the ratio of the sensed voltage to the divider’s input voltage (VCbias).
Figure 4. RATIO OF THM PIN TO CBIAS PIN OVER TEMPERATURE
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0
Divider Output
10
20
30
40
50
Degrees Centigrade
11 of 12
Share Link: 