LT1510CS8 Linear Technology, LT1510CS8 Datasheet - Page 12

• Manufacturer Part Number: LT1510CS8
• Description: IC BATT CHARGER CONST V/I 8SOIC
• Manufacturer: Linear Technology

Specifications of LT1510CS8

• Function: Charge Management
• Battery Type: Li-Ion, NiCd, NiMH
• Voltage - Supply: 6.2 V ~ 28 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LT1510/LT1510-5
APPLICATIONS
12
voltage decrease is detected as an indication of near full
charge. The charging current is then reduced to a much
lower value and maintained as a constant trickle charge.
An intermediate “top off” current may be used for a fixed
time period to reduce 100% charge time.
NiMH batteries are similar in chemistry to NiCd but have
two differences related to charging. First, the inflection
characteristic in battery voltage as full charge is ap-
proached is not nearly as pronounced. This makes it more
difficult to use dV/dt as an indicator of full charge, and
change of temperature is more often used with a tempera-
ture sensor in the battery pack. Secondly, constant trickle
charge may not be recommended. Instead, a moderate
level of current is used on a pulse basis ( 1% to 5% duty
cycle) with the time-averaged value substituting for a
constant low trickle.
Thermal Calculations
If the LT1510 is used for charging currents above 0.4A, a
thermal calculation should be done to ensure that junction
temperature will not exceed 125 C. Power dissipation in
the IC is caused by bias and driver current, switch resis-
tance, switch transition losses and the current sense
resistor. The following equations show that maximum
practical charging current for the 8-pin SO package
(125 C/W thermal resistance) is about 0.8A for an 8.4V
INTERNAL
RESISTOR
U
SENSE
INFORMATION
U
LT1510
Figure 7. Current Comparator for Initiating Float Time-Out
0.18
GND
W
SENSE
BAT
U
R1*
1.6k
R2
560k
R3
430k
1N4148
0.1 F
C1
D2
battery and 1.1A for a 4.2V battery. This assumes a 60 C
maximum ambient temperature. The 16-pin SO, with a
thermal resistance of 50 C/W, can provide a full 1.5A
charging current in many situations. The 16-pin PDIP falls
between these extremes. Graphs are shown in the Typical
Performance Characteristics section.
R
t
f = 200kHz (500kHz for LT1510-5)
3
2
OL
SW
–
+
P
P
P
P
= Effective switch overlap time 10ns
LT1011
SENSE
BIAS
DRIVER
SW
ADAPTER
OUTPUT
= Switch ON resistance 0.35
1
8
D1
1N4148
4
I
* TRIP CURRENT =
BAT
3 5
V
3.3V OR 5V
BAT
V
0
7
IN
I
mA V
BAT
18
2
2
R
R4
470k
V
SW
IN
7 5
V
BAT
IN
I
55
NEGATIVE EDGE
TO TIMER
BAT
mA
V
(R2 + R3)(0.18 )
BAT
2
V
1 5
2
R1(V
IN
1
mA V
0 012
BAT
1510 F06
V
)
30
BAT
t
OL
BAT
I
BAT
V
IN BAT
I
f