WM8311GEB/V Wolfson Microelectronics, WM8311GEB/V Datasheet - Page 286

• Manufacturer Part Number: WM8311GEB/V
• Description: POWER MANAGEMENT SUBSYSTEM, 121BGA
• Manufacturer: Wolfson Microelectronics

Specifications of WM8311GEB/V

• Supply Voltage: 5.5V
• No. Of Step-down Dc - Dc Converters: 4
• No. Of Ldo Regulators: 7
• Digital Ic Case Style: BGA
• No. Of Pins: 121
• No. Of Regulated Outputs: 9
• Operating Temperature Range: -40°C To
• Rohs Compliant: Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

WM8311
30.6 BATTERY TEMPERATURE MONITORING COMPONENTS
w
Battery temperature monitoring is performed using a reference voltage output on the NTCBIAS pin. A
potential divider is formed between the NTC bias resistor and the NTC thermistor component within
the battery pack. The voltage present at the NTCMON pin is used to determine the battery
temperature. The recommended connections and the derivation of V
Figure 44 Battery Temperature Monitoring
The voltage thresholds for the Hot/Cold Battery Temperature conditions are fixed in the WM8311:
If the NTC thermistor has a nominal resistance of 100kΩ at 25°C, and follows the Vishay Resistance-
Temperature Curve 1, then the above equations result in the Hot Battery threshold = 40°C and the
Cold Battery threshold = 0°C.
For example, if the NTC thermistor resistance is 53.4kΩ at 40°C, then V
following equation:
The upper and lower temperature thresholds can be adjusted by modification of the NTC bias
resistor and/or the addition of another resistor between the battery pack and the NTCMON pin.
If only the NTC bias resistor is adjusted, then either the upper or lower threshold can be selected, but
not both; the other threshold will be determined by the thermistor characteristics.
If an additional resistor is inserted between the battery pack and the NTCMON pin, then the upper
and lower thresholds can be independently selected, with the constraint that the upper and lower
thresholds must be at least 40°C apart.
The Cold Battery condition is detected when V
The Hot Battery condition is detected when V
WM8311
Battery temperature
Battery monitor
measurement
Main battery
connection
source
NTCBIAS
NTCMON
BATTVDD
GND
NTCMON
NTCMON
NTC bias resistor R
< 0.348 x V
> 0.765 x V
Single-cell
lithium battery
NTC thermistor R
V
NTCMON
NTCMON
PP, December 2009, Rev 3.0
NTCBIAS
=
is shown in Figure 44.
NTCBIAS
100k + R
NTCMON
BIAS
R
NTC
NTC
(100k)
is given by the
NTC
(100k at 25 C)
Pre-Production
x V
NTCBIAS
286