Datasheet LTC7124 (Analog Devices) - 7

LTC7124
PIN FUNCTIONS GND (Pins 1, 2, 7, 8, Exposed Pad 25/26):
The exposed
BOOST2 (Pin 15):
Boosted Floating Driver Supply for pads should be soldered to PCB ground for rated thermal Channel 2. The (+) terminal of the bootstrap capacitor performance. Connect all GND pins together with solid connects to this pin while the (–) terminal connects to ground plane. the SW2 pin. The normal operating voltage swing of this
V
pin ranges from INTVCC to VIN2 + INTVCC.
IN1 (Pin 3):
Input Voltage of the Channel 1 Step-Down Regulator. This input powers the INTVCC LDO.
INTVCC (Pin 16):
Low Dropout Regulator. Bypass with at
I
a low ESR cap of at least 2.2μF to ground.
LIM (Pin 4):
Current Limit Select Pin. Tying this pin to GND sets full current limit for both channels. Tying this
MODE/SYNC (Pin 17):
Burst Mode Select and Oscillator pin to INTVCC drops the current limit by a factor of 2 for Synchronization of the Step-Down Regulator. This pin can both channels. Floating this pin sets full current limit for be connected to INTVCC for Burst Mode operation (800mA Channel 1 and half current limit for Channel 2. minimum peak current clamp), GND for pulse skipping
RT (Pin 5):
Switching Frequency Program Pin. Connect mode (200mA minimum peak current clamp), or between an external resistor (between 208k to 19k) from this pin 1.0V and INTVCC – 1.2V for forced continuous mode. to GND to program the frequency from 500kHz to 4MHz, Furthermore, connecting MODE/SYNC to an external clock respectively. When RT is tied to INTV will synchronize the internal clock to the external clock and CC, spread spectrum mode of operation will be enabled. In addition, when spread put the part in forced continuous mode. However, syncing spectrum is enabled, syncing capability on the MODE/SYNC capability is disabled when spread spectrum is enabled. pin is disabled, and the part will operate in forced continuous
BOOST1 (Pin 18):
Boosted Floating Driver Supply for mode around a center frequency of 2.25MHz. Channel 1. The (+) terminal of the bootstrap capacitor
V
connects to this pin while the (–) terminal connects to
IN2 (Pin 6):
Input Voltage of the Channel 2 Step-Down Regulator. May be a different voltage than V the SW1 pin. The normal operating voltage swing of this IN1. pin ranges from INTVCC to VIN1 + INTVCC.
FB2 (Pin 9):
Feedback Input to the Error Amplifier of the Channel 2 Step-Down Regulator. Connect resistor divider
SW1 (Pins 19, 20):
Switch Node Connection to the tap to this pin. The output voltage can be adjusted from Inductor of the Channel 1 Step-Down Regulator. 0.6V to 0.99 • VIN2 by: VOUT2 = 0.6V × [1 + (R1/R2)].
RUN1 (Pin 21):
Logic Controlled RUN Input to Channel 1.
ITH2 (Pin 10):
Channel 2 Error Amplifier Output and Do not leave this pin floating. Logic High activates channel Switching Regulator Compensation Pin. Connect this pin 1 of the step-down regulator. to appropriate external components to compensate the
PGOOD1 (Pin 22):
Open Drain Power Good Indicator for regulator loop frequency response or to INTVCC to use Channel 1. the default internal compensation.
ITH1 (Pin 23):
Channel 1 Error Amplifier Output and
PGOOD2 (Pin 11):
Open Drain Power Good Indicator for Switching Regulator Compensation Pin. Connect this pin Channel 2. to appropriate external components to compensate the
RUN2 (Pin 12):
Logic Controlled RUN Input to Channel 2. regulator loop frequency response or connect to INTVCC Do not leave this pin floating. Logic High activates to use the default internal compensation. channel 2 of the step-down regulator.
FB1 (Pin 24):
Feedback Input to the Error Amplifier of the
SW2 (Pins 13, 14):
Switch Node Connection to the Inductor Channel 1 Step-Down Regulator. Connect resistor divider of the Channel 2 Step-Down Regulator. tap to this pin. The output voltage can be adjusted from 0.6V to 0.99 • VIN1 by: VOUT1 = 0.6V × [1 + (R1/R2)]. 7124fa For more information www.linear.com/LTC7124 7