LTC3586_15 Datasheet, PDF (11/36 Pages) Linear Technology – High Efficiency USB Power Manager with Boost, Buck-Boost and Dual Bucks

LTC3586/LTC3586-1
Pin Functions
I_LIM0, I_LIM1 (Pins 1, 2): Logic Inputs. I_LIM0 and I_LIM1
control the current limit of the PowerPath switching
regulator. See Table 1.
Table 1. USB Current Limit Settings
(I_LIM1)
0
(I_LIM0)
0
USB SETTING
1x Mode (USB 100mA Limit)
0
1
10x Mode (Wall 1A Limit)
1
0
Suspend
1
1
5x Mode (USB 500mA Limit)
LDO3V3 (Pin 3): 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 watch dog 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 4): 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 current limit
settings are available via user input which will typically
correspond to the 500mA and 100mA USB specifications.
A multilayer ceramic averaging capacitor is required at
CLPROG for filtering.
NTC (Pin 5): 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.
V_OUT4 (Pins 6, 7): Power Output for the (Boost) Switching
Regulator 4. A 10µF MLCC capacitor should be placed as
close to the pins as possible.
SW4 (Pin 8): Switch Node for the (Boost) Switching
Regulator 4. An external inductor connects between this
pin and V_IN4.
MODE (Pin 9): Digital Input. The MODE pin controls dif-
ferent modes of operation for the switching regulators
according to Table 2.
Table 2. Switching Regulators Mode
REGULATION MODE
Mode
Buck
Buck-Boost
0
Pulse-Skip
PWM
1
Burst
Burst
Boost
Pulse-Skip
Pulse-Skip
FB4 (Pin 10): Feedback Input for the (Boost) Switching
Regulator 4. When the control loop is complete, the volt-
age on this pin servos to 0.8V.
FB3 (Pin 11): Feedback Input for (Buck-Boost) Switching
Regulator 3. When regulator 3’s control loop is complete,
this pin servos to 0.8V.
V_C3 (Pin 12): Output of the Error Amplifier and Voltage Com-
pensation Node for (Buck-Boost) Switching Regulator 3.
External Type I or Type III compensation (to FB3) connects
to this pin. See the Applications Information section for
selecting buck-boost compensation components.
SWAB3 (Pin 13): Switch Node for (Buck-Boost) Switch-
ing Regulator 3. Connected to Internal Power Switches A
and B. An external inductor connects between this node
and SWCD3.
V_IN3 (Pins 14, 15): Power Input for (Buck-Boost) Switching
Regulator 3. These pins will generally be connected to V_OUT.
A 1µF MLCC capacitor is recommended on these pins.
V_OUT3 (Pins 16, 17): Output Voltage for (Buck-Boost)
Switching Regulator 3.
EN3 (Pin 18): Digital Input. This input enables the
buck-boost switching regulator 3.
SWCD3 (Pin 19): Switch Node for (Buck-Boost) Switch-
ing Regulator 3 Connected to Internal Power Switches C
and D. An external inductor connects between this node
and SWAB3.
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