ltc3566 Linear Technology Corporation, ltc3566 Datasheet - Page 9

• Manufacturer Part Number: ltc3566
• Description: High Ef?ciency Usb Power Manager Plus 1a Buck-boost Converter
• Manufacturer: Linear Technology Corporation

TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
LDO3V3 (Pin 1): 3.3V LDO Output Pin. This pin provides
a regulated, always-on, 3.3V supply voltage. LDO3V3
gets its power from V
such as a watchdog microprocessor or real time clock.
A 1μF capacitor is required from LDO3V3 to ground. If
the LDO3V3 output is not used it should be disabled by
connecting it to V
CLPROG (Pin 2): USB Current Limit Program and Moni-
tor Pin. A resistor from CLPROG to ground determines
the upper limit of the current drawn from the V
A fraction of the V
when the synchronous switch of the PowerPath switching
regulator is on. The switching regulator delivers power
until the CLPROG pin reaches 1.188V. Several V
rent limit settings are available via user input which will
typically correspond to the 500mA and the 100mA USB
specifi cations. A multilayer ceramic averaging capacitor
or R-C network is required at CLPROG for fi ltering.
NTC (Pin 3): Input to the Thermistor Monitoring Circuits.
The NTC pin connects to a battery’s thermistor to deter-
mine if the battery is too hot or too cold to charge. If the
battery’s temperature is out of range, charging is paused
until it re-enters the valid range. A low drift bias resistor
is required from V
from NTC to ground. If the NTC function is not desired,
the NTC pin should be grounded.
3.333
3.322
3.311
3.300
3.289
3.278
3.267
1
Buck-Boost Regulator Load
Regulation
V
T
TYPE 3 COMPENSATION
OUT1
A
= 27°C
= 3.3V
10
I
OUT
BUS
LOAD
BUS
.
(mA)
to NTC and a thermistor is required
OUT
current is sent to the CLPROG pin
100
. It may be used for light loads
V
V
V
IN1
IN1
IN1
= 3V
= 3.6V
= 4.5V
3566 G28
1A
300
250
200
150
100
50
0
2.7
Reduction in Current
Deliverability at Low V
BUS
BUS
3.1
cur-
pin.
3.5
V
STEADY STATE I
START-UP WITH A
RESISTIVE LOAD
START-UP WITH A
CURRENT SOURCE LOAD
IN1
TYPE 3 COMPENSATION
3.9
FB1 (Pin 4): Feedback Input for the (Buck-Boost) Switching
Regulator. When the regulator’s control loop is complete,
this pin servos to a fi xed voltage of 0.8V.
V
pensation Node for the (Buck-Boost) Switching Regulator.
External Type I or Type III compensation (to FB1) connects
to this pin. See Applications Information section for select-
ing buck-boost loop compensation components.
GND (Pins 6, 12): Power GND pins for the buck-boost.
SWAB1 (Pin 7): Switch Node for the (Buck-Boost) Switch-
ing Regulator. Connected to internal power switches A
and B. External inductor connects between this node and
SWCD1.
MODE (Pin 8): Logic Input. Mode enables Burst Mode
functionality for the buck-boost switching regulator when
pin is set high. Has a 1.6μA internal pull-down current
source.
V
Regulator. This pin will generally be connected to V
(Pin 20). A 1μF(min) MLCC capacitor is recommended
on this pin.
V
Boost) Switching Regulator.
(V)
C1
IN1
OUT1
(Pin 5): Output of the Error Amplifi er and Voltage Com-
4.3
(Pin 9): Power Input for the (Buck-Boost) Switching
IN1
V
(Pin 10): Regulated Output Voltage for the (Buck-
OUT1
T
LOAD
A
= 27°C
4.7
= 3.3V
3566 G29
T
A
= 25°C unless otherwise noted.
DC 200mA/DIV
AC 100mV/DIV
CH1 V
CH2 I
LOAD
OUT1
Buck-Boost Regulator Load Step,
0mA to 300mA
V
V
L = 2.2μH
C
IN1
OUT1
OUT
= 4.2V
= 47μH
= 3.3V
100μs/DIV
LTC3566
9
3566p
3566 G30
OUT