LTC3566-2_15 Datasheet, PDF (9/28 Pages) Linear Technology – High Efficiency USB Power Manager Plus 1A Buck-Boost Converter

LTC3566/LTC3566-2
TYPICAL PERFORMANCE CHARACTERISTICS T_A = 25°C unless otherwise noted.
Buck-Boost Regulator Load
Regulation
3.333
3.322
V_IN1 = 3V
V_IN1 = 3.6V
V_IN1 = 4.5V
3.311
3.300
3.289
3.278 V_OUT1 = 3.3V
T_A = 27°C
TYPE 3 COMPENSATION
3.267
1
10
100
I_LOAD (mA)
1A
3566 G28
Reduction in Current
Deliverability at Low V_IN1
300
STEADY STATE I_LOAD
START-UP WITH A
250
RESISTIVE LOAD
START-UP WITH A
CURRENT SOURCE LOAD
200
Buck-Boost Regulator Load Step,
0mA to 300mA
CH1 V_OUT1
AC 100mV/DIV
150
100
CH2 I_LOAD
DC 200mA/DIV
50
V_OUT1 = 3.3V
T_A = 27°C
TYPE 3 COMPENSATION
0
2.7 3.1 3.5 3.9 4.3 4.7
V_IN1 (V)
3566 G29
V_IN1 = 4.2V
V_OUT1 = 3.3V
L = 2.2μH
C_OUT = 47μF
100μs/DIV
3566 G30
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_OUT. It may be used for light loads
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_OUT.
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_BUS pin.
A fraction of the V_BUS current is sent to the CLPROG pin
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_BUS cur-
rent limit settings are available via user input which will
typically correspond to the 500mA and the 100mA USB
specifications. A multilayer ceramic averaging capacitor
or R-C network is required at CLPROG for filtering.
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_BUS to NTC and a thermistor is required
from NTC to ground. If the NTC function is not desired,
the NTC pin should be grounded.
FB1 (Pin 4): Feedback Input for the (Buck-Boost) Switching
Regulator. When the regulator’s control loop is complete,
this pin servos to a fixed voltage of 0.8V.
V_C1 (Pin 5): Output of the Error Amplifier and Voltage Com-
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_IN1 (Pin 9): Power Input for the (Buck-Boost) Switching
Regulator. This pin will generally be connected to V_OUT
(Pin 20). A 1μF(min) MLCC capacitor is recommended
on this pin.
V_OUT1 (Pin 10): Regulated Output Voltage for the (Buck-
Boost) Switching Regulator.
3566fb
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