LT1511ISW Linear Technology, LT1511ISW Datasheet - Page 8

• Manufacturer Part Number: LT1511ISW
• Description: IC BATT CHRGR CONST I/V 3A24SOIC
• Manufacturer: Linear Technology

Specifications of LT1511ISW

• Function: Charge Management
• Battery Type: Li-Ion, NiCd, NiMH
• Voltage - Supply: 6 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (0.300", 7.50mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LT1511
OPERATION
The LT1511 is a current mode PWM step-down (buck)
switcher. The battery DC charging current is programmed
by a resistor R
pin (see Block Diagram). Amplifier CA1 converts the
charging current through R
I
output of CA1 with the programmed current and drives the
PWM loop to force them to be equal. High DC accuracy is
achieved with averaging capacitor C
has both AC and DC components. I
and generates a ramp signal that is fed to the PWM control
comparator C1 through buffer B1 and level shift resistors
8
TEST CIRCUITS
PROG
fed into the PROG pin. Amplifier CA2 compares the
+
PROG
0.65V
U
(or a DAC output current) at the PROG
1k
0.047 F
V
C
S1
to a much lower current
60k
PROG
+
–
PROG
LT1006
LT1511
0.47 F
I
PROG
goes through R1
. Note that I
CA2
R
+
–
PROG
20k
PROG
10k
V
300
REF
1 F
PROG
Test Circuit 2
+
Test Circuit 1
LT1511
2.465V
1k
R
PROG
PROG
VA
+
–
R2 and R3, forming the current mode inner loop. The
Boost pin drives the switch NPN Q
reduces power loss. For batteries like lithium-ion that
require both constant-current and constant-voltage charg-
ing, the 0.5%, 2.465V reference and the amplifier VA
reduce the charging current when battery voltage reaches
the preset level. For NiMH and NiCd, VA can be used for
overvoltage protection. When input voltage is not present,
the charger goes into low current (3 A typically) sleep
mode as input drops down to 0.7V below battery voltage.
To shut down the charger, simply pull the V
a transistor.
–
+
LT1013
V
REF
10k
CA1
+
–
OVP
1511 • TC02
SPIN
SENSE
BAT
200
200
R
R
S3
S2
SW
into saturation and
R
10
S1
+
1511 • TC01
V
BAT
C
pin low with