LT3472 UUUPI FU CTIO SSWP (Pin 1): Switch Pin for Positive (Boost) Channel. SSN (Pin 7): Soft Start-Up Pin for Inverter. Connect a cap Connect boost inductor here. here for soft start-up. Leave open for quick start-up. This pin is connected to 1.25V with a 50k resistor internally. VIN (Pin 2): Input Supply Pin. Must be locally bypassed with a X5R or X7R type ceramic capacitor. FBP (Pin 8): Feedback Pin for Boost. Connect boost feedback resistor R1 from this Pin to V SHDN (Pin 3): Shutdown Pin. Connect to 0.8V or higher to O1. Choose R1 according to V enable device, 0.3V or less to disable device. O1 = 1.25 • (1 + R1/50k). Pin voltage = 1.25V when regulated. SWN (Pin 4): Switch Pin for Negative (Inverter) Channel. SSP (Pin 9): Soft Start-Up Pin for Boost. Connect a cap Connect inverter input inductor and flying capacitor here. here for soft start-up. Leave open for quick start-up. This DN (Pin 5): Anode of Internal Schottky for Inverter. pin is connected to 1.25V with a 50k resistor internally. Connect inverter output inductor and flying capacitor V here. POS (Pin 10): Output Pin for Boost. Connect boost output capacitor here. FBN (Pin 6): Feedback Pin for Inverter. Connect feedback GND (Exposed Pad) (Pin 11): GND Pin. Tie directly to resistor R2 from this pin to VO2. Choose R2 according to ground plane through multiple vias under the package for VO2 = 1.25 • R2/50k. Pin voltage = 0V when regulated. optimum thermal performance. WBLOCK DIAGRA SWP 1 COMPARATOR DP FBP 8 – 10 V A1 – X1 DRIVER 1 POS 50k + A2 R Q Q1 S + – VIN 2 ∑ + VREF RAMP 1.25V 11 GND GENERATOR 50k 1.2MHz 3 SHDN OSCILLATOR COMPARATOR FBN 6 + DRIVER 2 A3 – X2 4 SWN S – A4 R Q Q2 + SSN 7 – 50k ∑ 1.25V + DN 50k RAMP 5 DN GENERATOR SSP 9 3472 BD Figure 1. LT3472 Block Diagram 3472f 5
