L6924U STMicroelectronics, L6924U Datasheet - Page 25

• Manufacturer Part Number: L6924U
• Description: Battery Management USB Battery Charger System w/integra
• Manufacturer: STMicroelectronics

Specifications of L6924U

• Product: Charge Management
• Battery Type: Li-Ion
• Output Voltage: 4.2 V
• Output Current: 30 mA
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Package / Case: VFQFPN
• Mounting Style: SMD/SMT
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6924U
charge the battery, only when the voltage at the TH pin goes under V
(typ).
For what concerns the high temperature limit, when the TH pin voltage falls under the
V
voltage reaches the V
When the battery is at the low temperature limit, the TH pin voltage is 900 mV. The correct
resistance ratio to set the low temperature limit at 0 °C can be found with the following
equation:
Equation 12
Where R
NTC at 0 °C. Since at the low temperature limit V
Equation 13
It follows that:
Equation 14
Similarly, when the battery is at the high temperature limit, the TH pin voltage is 225 mV. The
correct resistance ratio to set the high temperature limit at 50 °C can be found with the
following equation:
Equation 15
Where R
that:
Equation 16
Consequently:
Equation 17
MAXTH
= 12.5 % of V
UP
NTC50°C
is the pull-up resistor, V
is the value of the NTC at 50 °C. Considering V
MAXTH_HYS
REF
(225 mV Typ.), the L6924U stops the charge until the TH pin
V
V
Doc ID 14716 Rev 2
. 0
MAXTH
MINTH
0
225
= 248 mV (typ.).
9 .
REF
Application information: monitoring and protection
=
=
=
=
R
1
R
V
V
1
NTC
is equal to 1.8 V, and R
8 .
NTC
8 .
REF
REF
×
50
×
° 0
R
°
×
×
C
R
C
UP
UP
R
R
=
=
R
UP
UP
R
+
MINTH
NTC
R
+
R
NTC
R
R
R
UP
7
UP
+
+
R
NTC
NTC
0
NTC
50
NTC
R
°
R
C
°
0
NTC
50
NTC
= 900 mV:
C
0
°
C
50
°
°
C
C
°
50
0
C
°
C
°
C
NTC0°C
MAXTH
MINTH_HYS
is the value of the
= 225 mV it follows
= 780 mV
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