AS1332-BWLT – austriamicrosystems
650 mA, 2 MHz Step-Down DC-DC Converter for RF Power Amplifiers
Complete Quick-Reference Datasheet Summary

1. Device IdentificationOrdering Code: AS1332-BWLTPackage: 8-pin WL-CSP (Wafer-Level Chip-Scale)Package Marking: ASQWRoHS / Pb-free: YesTape & Reel: 7-in reel, 3 k pcs typical
2. Description & Target Applications

• Synchronous buck converter optimized to power RF PAs in Li-Ion–powered handsets
• Dynamic 1.3 V – 3.16 V output set by analog VCON pin (gain = 2.5 V/V)
• 2 MHz fixed-PWM operation → tiny passives, low output ripple, EMI-friendly
• 96 % peak efficiency (3.6 VIN, 3.16 VOUT, 400 mA)
• < 0.01 µA shutdown current
• Ideal for: cellular phones, handheld radios, RF PC-cards, battery-powered RF modules

1. Absolute Maximum Ratings (stress only)PVIN, VDD to AGND ........................ –0.3 V → +7 VEN, FB, VCON .............................. –0.3 V → VDD+0.3 V (≤ 7 V)SW ........................................ –0.3 V → PVIN+0.3 VTJ max .................................... +150 °CTstg ....................................... –65 °C → +150 °CESD HBM ................................... 2 kV
2. Operating Range (functional)VIN ........................................ 2.7 V – 5.5 V (single Li-Ion cell)Iload max ................................. 650 mA (PWM mode)TA ......................................... –40 °C → +85 °CTJ (recommended) .......................... –40 °C → +125 °C
3. Electrical Characteristics (TJ = 25 °C, VIN = 3.6 V unless noted)
4. Feedback / Output
   VFB,min (VCON = 0.4 V) ................... 1.21 V min, 1.30 V typ, 1.39 V max
   VFB,max (VCON = 1.27 V) ................. 3.03 V min, 3.17 V typ, 3.29 V max
   Gain (VOUT vs VCON) ...................... 2.5 V/V (linear range 0.556 V ≤ VCON ≤ 1.208 V)
5. Supply Currents
   IQ (no switching) .......................... 1 mA typ, 1.4 mA max
   ISHDN (EN = 0 V) .......................... 0.01 µA typ, 2 µA max
6. Power Switches
   PFET RDS(on) .............................. 140 mΩ typ / 200 mΩ max @ 200 mA, 25 °C
   NFET RDS(on) .............................. 300 mΩ typ / 415 mΩ max @ –200 mA, 25 °C
   Peak current limit ........................ 1.1 A typ, 0.935 A min, 1.2 A max
   FOSC ...................................... 2 MHz typ (1.8 – 2.2 MHz over temp)
7. Control Inputs
   EN VIH .................................... 1.2 V min
   EN VIL .................................... 0.5 V max
   VCON input resistance ..................... 100 kΩ typ
   VCON leakage .............................. ±10 µA
8. Typical System Performance (@ 25 °C)

• Turn-on time (EN ↑ → 3.16 V) ........... 210 µs typ, 750 µs max
• VCON response (1.3 V → 3.16 V) ......... 30 µs typ
• Load transient (10 mA ↔ 400 mA) ........ ±50 mV deviation, <20 µs recovery
• Output ripple (PWM, 200 mA) ............ 10 mVPP typ
• PSRR (10 kHz, 100 mVPP) ................ 40 dB typ

1. Functional Description

• Current-mode buck with synchronous rectification → no external Schottky
• VCON analog input directly sets VOUT (clamped below 0.484 V and above 1.312 V)
• Cycle-by-cycle 1.2 A valley current limit; timed hiccup when VOUT < 0.375 V
• Soft-start & thermal shutdown @ +150 °C (hysteresis ≈ 15 °C)
• Fixed 2 MHz allows 3.3 µH inductor, 0805/0603 ceramic caps

1. Recommended External ComponentsL1 .......................................... 3.3 µH (±20 %), DCR ≤ 100 mΩ, sat ≥ 1.5 AExample: Coilcraft LPS4018-332ML_ (3.9 mm × 3.9 mm × 1.7 mm)CIN ........................................ 10 µF ±20 %, X5R/X7R, 6.3 V or 16 VExample: Murata GRM21BR60J106KE19 (0805)COUT ....................................... 4.7 µF ±20 %, X5R/X7R, 6.3 V – 16 VExample: Murata GRM21BR61C475KA88 (0805)Optional larger COUT (≤ 22 µF) lowers ripple & improves transients.
2. Pinout (8-bump WL-CSP, 0.4 mm pitch)
3. A1  PVIN   – Power input to PFET switch
   A2  SW     – Switch node (inductor connection)
   A3  PGND   – Power ground
   B1  VDD    – Analog supply (bypass to AGND)
   B3  AGND   – Analog ground (Kelvin to PGND)
   C1  EN     – Enable (active-high, 1.2 V threshold)
   C2  VCON   – Analog control voltage (0.52 V – 1.27 V)
   C3  FB     – Feedback / output sense (connect to COUT +)
4. Typical Application CircuitLi-Ion 2.7-5.5 V+–– PVIN (A1)| +–– VDD (B1)| | +10 µF| | || +–– EN (C1) ← MCU GPIO| || +–– VCON (C2) ← DAC / PWM filtered| |+–– L 3.3 µH – SW (A2) –+–– FB (C3) –+–– VOUT 1.3-3.16 V| | |PGND (A3) – AGND (B3) –+–– 4.7 µF –+–– RF PA
5. PCB Layout Guidelines

• Minimise pulse-current loop: CIN → PVIN → SW → L → COUT → PGND → CIN
• Place CIN as close as possible to PVIN & PGND; use multiple vias to ground plane
• Keep SW node short and away from feedback/control traces to reduce EMI
• Kel-connect AGND & PGND at one point near device; star-connect to system ground
• Flood unused copper on top layer tied to PGND for heat-spreading (θJA improvement)

1. Packing & Ordering InformationOrder code: AS1332-BWLTMarking: ASQWPackage: 8-pin WL-CSP, 600 µm ±30 µm body thickness, 1515 µm ±20 µm ball pitchReel qty: 3 000 pcs (standard)MSL: 3 (168 h @ ≤30 °C/60 % RH)