LT1512IS8#TR Linear Technology, LT1512IS8#TR Datasheet - Page 5

• Manufacturer Part Number: LT1512IS8#TR
• Description: IC CHARGER BATT CONST V/I 8SOIC
• Manufacturer: Linear Technology

Specifications of LT1512IS8#TR

• Function: Charge Management
• Battery Type: All Battery Types
• Voltage - Supply: 2.7 V ~ 25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Output Current: 1A
• Output Voltage: 30V
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (max): 25V
• Operating Temp Range: -40C to 85C
• Package Type: SOIC N
• Mounting: Surface Mount
• Pin Count: 8
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

PIN FUNCTIONS
I
current. It is the input to a current sense amplifi er that
controls charging current when the battery voltage is below
the programmed voltage. During constant-current opera-
tion, the I
this pin is 5kΩ, so fi lter resistance (R4, Figure 1) should be
less than 50Ω. The 24Ω, 0.22μF fi lter shown in Figure 1 is
used to convert the pulsating current in the sense resistor
to a smooth DC current feedback signal.
S/S: This pin can be used for shutdown and/or synchro-
nization. It is logic level compatible, but can be tied to V
if desired. It defaults to a high ON state when fl oated. A
logic low state will shut down the charger to a micropower
state. Driving the S/S pin with a continuous logic signal of
600kHz to 800kHz will synchronize switching frequency
to the external signal. Shutdown is avoided in this mode
with an internal timer.
V
low ESR capacitor located right next to the IC chip. The
BLOCK DIAGRAM
FB
IN
: The current feedback pin is used to sense charging
: The input supply pin should be bypassed with a
FB
pin regulates at –100mV. Input resistance of
I
FB
FB
1.245V
GND S
REF
5k
62k
S/S
+
–
–
–
+
DELAY AND RESET
SYNC
I
FBA
EA
SHUTDOWN
500kHz
OSC
LOW DROPOUT
V
2.3V REG
C
IN
Figure 2
COMP
LOGIC
V
IN
grounded end of the capacitor must be connected directly
to the ground plane to which the GND pin is connected.
GND S, GND: The LT1512 uses separate ground pins for
switch current (GND) and the control circuitry (GND S).
This isolates the control ground from any induced volt-
age created by fast switch currents. Both pins should be
tied directly to the ground plane, but the external control
circuit components such as the voltage divider, frequency
compensation network and I
connected directly to the GND S pin or to the ground plane
close to the point where the GND S pin is connected.
V
carrying up to 1.5A of current with fast rise and fall times.
Keep the traces on this pin as short as possible to mini-
mize radiation and voltage spikes. In particular, the path
in Figure 1 which includes SW to C2, D1, C1 and around
to the LT1512 ground pin should be as short as possible
to minimize voltage spikes at switch turn-off.
SW
: The switch pin is the collector of the power switch,
A
V
≈ 6
IA
+
–
DRIVER
ANTI-SAT
FB
bypass capacitor should be
GND
SW
SWITCH
0.08Ω
1512 F02
LT1512
1512fa
5