LTC3535_15 Datasheet, PDF (7/16 Pages) Linear Technology – Dual Channel 550mA 1MHz Synchronous Step-Up DC/DC Converter

LTC3535
PIN FUNCTIONS
V_OUT1 (Pin 1): Output Voltage Sense and Drain of the
Internal Synchronous Rectifier for Channel 1. PCB trace
length from V_OUT1 to the output filter capacitor (4.7µF
minimum) should be as short and wide as possible.
SW1 (Pin 2): Switch Pin for Channel 1. Connect inductor
between SW1 and V_IN1. Keep PCB trace lengths as short
and wide as possible to reduce EMI. If the inductor current
falls to zero, or SHDN1 is low, an internal anti-ringing switch
is connected from SW1 to V_IN1 to minimize EMI.
GND (Pins 3, 6, Exposed Pad Pin 13): Signal and Power
Ground. Provide a short direct PCB path between GND
and the (–) side of the input and output capacitors. The
exposed pad must be soldered to the PCB ground plane.
It serves as another ground connection and as a means
of conducting heat away from the die.
V_OUT2 (Pin 4): Output Voltage Sense and Drain of the
Internal Synchronous Rectifier for Channel 2. PCB trace
length from V_OUT2 to the output filter capacitor (4.7µF
minimum) should be as short and wide as possible.
SW2 (Pin 5): Switch Pin for Channel 2. Connect inductor
between SW2 and V_IN2. Keep PCB trace lengths as short
and wide as possible to reduce EMI. If the inductor current
falls to zero, or SHDN2 is low, an internal anti-ringing switch
is connected from SW2 to V_IN2 to minimize EMI.
V_IN2 (Pin 7): Battery Input Voltage for Channel 2. Connect
a minimum of 1µF ceramic decoupling capacitor from this
pin to ground.
SHDN2 (Pin 8): Logic Controlled Shutdown Input for Chan-
nel 2. There is an internal 4MΩ pull-down on this pin.
SHDN = High: Normal operation.
SHDN = Low: Shutdown, quiescent current < 1µA.
FB2 (Pin 9): Feedback Input to the g_m Error Amplifier of
Channel 2. Connect resistor divider tap to this pin. The
output voltage can be adjusted from 1.5V to 5.25V by:
V_OUT = 1.195V × [1 + (R4/R3)]
V_IN1 (Pin 10): Battery Input Voltage for Channel 1. Connect
a minimum of 1µF ceramic decoupling capacitor from this
pin to ground.
SHDN1 (Pin 11): Logic Controlled Shutdown Input for Chan-
nel 1. There is an internal 4MΩ pull-down on this pin.
SHDN = High: Normal operation.
SHDN = Low: Shutdown, quiescent current < 1µA.
FB1 (Pin 12): Feedback Input to the g_m Error Amplifier
of Channel 1. Connect resistor divider tap to this pin. The
output voltage can be adjusted from 1.5V to 5.25V by:
V_OUT = 1.195V × [1 + (R2/R1)].
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