L6924D STMicroelectronics, L6924D Datasheet - Page 26

• Manufacturer Part Number: L6924D
• Description: IC BATTERY CHARGER SYS 16-VFQFPN
• Manufacturer: STMicroelectronics

Specifications of L6924D

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 2.5 V ~ 12 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-VFQFN
• Product: Charge Management
• Output Current: 30 mA
• Operating Supply Voltage: 2.5 V to 12 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• For Use With: 497-8428 - BOARD EVAL CHARGER ST7260/L6924D497-8247 - BOARD EVAL FOR L6924UTR497-5504 - EVAL BOARD FOR L6924D
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application information: monitoring and protection
26/38
Based on
Equation 20
The temperature hysteresis can be estimated by the equation:
Equation 21
Where V
threshold on the falling edge, and NTC
the NTC at temperature (T) expressed in % resistance change per °C. For NTC
the characteristics of the NTC manufacturers (e.g. the 2322615 series by VISHAY). At the
low temperature, the hysteresis is approximately:
Equation 22
Obviously at the high temperature hysteresis is:
Equation 23
Considering typical values for NTC
Equation 24
And:
Equation 25
If a PTC connected to GND is used, the selection is the same as above, the only difference
is when the battery temperature increases, the voltage on the TH pin increases, and vice
versa. For applications that do not need a monitor of the battery temperature, the NTC can
be replaced with a simple resistor whose value is one half of the pull-up resistor R
In this case, the voltage at the TH pin is always inside the voltage window, and the charge is
always enabled.
TH
Equation 16:
is the pin voltage threshold on the rising edge, V
and
T
Equation 19:
T
HYS
T
HYS
Doc ID 11908 Rev 9
HYS
50
T
0
°
HYS
°
C
C
50
T
0°C
=
°
=
0
HYS
C
°
C
225
900
=
and NTC
T
225
900
=
R
R
=
(-%/°C) is the negative temperature coefficient of
225
NTC
900
mV
NTC
mV
, it derives that:
900
225
V
mV
mV
V
TH
50
TH
mV
0
mV
−
°
mV
−
°
mV
×
C
×
C
−
248
×
780
50°C
. 0
. 0
V
×
×
=
NTC
−
039
TH
051
−
NTC
NTC
mV
7
mV
780
, the hysteresis is:
_
248
HYS
T
mV
≅
0
≅
50
mV
°
−
2
C
2
°
5 .
C
5 .
TH_HYS
o
C
o
C
is the pin voltage
T
values, see
UP
L6924D
.