LTC3883 Datasheet, PDF (12/112 Pages) Linear Technology – Single Phase Step-Down DC/DC Controller with Digital Power System Management

LTC3883/LTC3883-1
Typical Performance Characteristics
DC Output Current Matching in a
2-Phase System (LTC3883)
25
20
15
10
5
CHAN 0
CHAN 1
0
0 5 10 15 20 25 30 35 40
TOTAL CURRENT (A)
3883 G28
Dynamic Current Sharing During a
Load Transient in a 2-Phase System
CURRENT
5A/DIV
V_IN = 12V
V_OUT = 1.8V
f_SW = 500kHz
L = 0.4µH
15A TO 5A LOAD STEP
5µs/DIV
3883 G29
Dynamic Current Sharing During a
Load Transient in a 2-Phase System
CURRENT
5A/DIV
V_IN = 12V
V_OUT = 1.8V
f_SW = 500kHz
L = 0.4µH
5A TO 15A LOAD STEP
5µs/DIV
3883 G30
Pin Functions
V_{IN_SNS} (Pin 1): Input Current Sense Comparator Input.
The (–) input to the input current comparator is normally
connected to the supply side of the input current sense
resistor through a 100Ω resistor. If the input current
sense amplifier is not used, this pin must be shorted to
the I_{IN_SNS} and V_IN pins.
I_{IN_SNS} (Pin 2): Input Current Sense Comparator Input.
The (+) input to the input current comparator is normally
connected to the power stage side of the input current
sense resistor through a 100Ω resistor. If the input current
sense amplifier is not used, this pin must be shorted to
the V_{IN_SNS} and V_IN pins.
I_SENSE+ (Pin 3): Current Sense Comparator Input. The (+)
input to the current comparator is normally connected
to the DCR sensing network or current sensing resistor.
I_SENSE– (Pin 4): Current Sense Comparator Input. The (–)
input is connected to the output.
SYNC (Pin 5): External Clock Synchronization Input and
Open-Drain Output Pin. If an external clock is present at
this pin, the switching frequency will be synchronized to
the external clock. If clock master mode is enabled, this
pin will pull low at the switching frequency with a 500ns
pulse width to ground. A resistor pull-up to 3.3V is required
in the application.
12
SCL (Pin 6): Serial Bus Clock Input. A pull-up resistor to
3.3V is required in the application.
SDA (Pin 7): Serial Bus Data Input and Output. A pull-up
resistor to 3.3V is required in the application.
ALERT (Pin 8): Open-Drain Digital Output. Connect the
SMBALERT signal to this pin.
GPIO (Pin 9): Digital Programmable General Purpose
Inputs and Outputs. Open-drain output.
PGOOD (Pin 10): Digital Power Good Indicator. Open-
drain output.
RUN (Pin 11): Enable Run Input. Logic high on this pin
enables the controller. This pin requires a resistor pull-
up to 3.3V in the application and should be driven by an
open-drain digital output.
DNC (Pins 12, 16): Do Not Connect to This Pin.
ASEL (Pin 13): Serial Bus Address Configuration Input.
Connect a ±1% resistor divider between the chip V_DD25
ASEL and GND in order to select the 4LSBs of the serial bus
interface address. A resistor divider on ASEL is required
if there are more than one LTC3883 on the same board
to assure the user can independently program each IC. If
the pin is left open, the IC will use the value programmed
in the NVM. Minimize capacitance when the pin is open
to assure accurate detection of the pin state.
3883f