36VIN, 3A, High Efficiency Synchronous Step-Down Converter with Low Quiescent Current

RTQ2105-QA Feature Product

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The RTQ2105 is a 3A, high-efficiency, current mode synchronous step-down converter which is optimized for automotive applications. The device operates with input voltages from 3V to 36V and is protected from load dump transients up to 42V, eases input surge protection design. The device can program the output voltage between 0.8V to VIN. The low quiescent current design with the integrated low RDS(ON) power MOSFETs achieves high efficiency over the wide load range. The peak current mode control with simple external compensation allows the use of small inductors and results in fast transient response and good loop stability.

The wide switching frequency of 300kHz to 2200kHz allows for efficiency and size optimization when selecting the output filter components. The ultra-low minimum on-time enable constant-frequency operation even at very high step-down ratios. For switching noise sensitive applications, it can be externally synchronized from 300kHz to 2200kHz. The optional spread-spectrum frequency modulation further helping systems designers with better EMC management.

The RTQ2105 offers precise constant current and constant voltage regulation. It is ideally suited for USB power delivery or charging super-capacitors. For applications that use long cable, the RTQ2105 offers cable drop compensation as well to maintain accurate regulation at the end of the long cable.

The RTQ2105 provides complete protection functions such as input under voltage lockout, output under voltage protection, over current protection, and thermal shutdown. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The RTQ2105 is available in WET-WQFN-24SL 4x4 (W-Type) package.


  • Automotive Systems
  • Car Camera Module and Car Cockpit Systems
  • Connected Car Systems
  • Point of Load Regulator in Distributed Power Systems
  • Digital Set Top Boxes
  • Broadband Communications
  • USB Power Chargers
Key Spec.
Status Active
Vin (min) (V) 3
Vin (max) (V) 36
Number of Outputs 1
Vout (min) (V) 0.8
Vout (max) (V) 36.0
Output Adj. Method Resistor
Iout (max) (A) 3
Current Limit (typ) (A) 2.2;5.5
Freq (min) (kHz) 300
Freq (max) (kHz) 2200
Ext Sync Yes
Ron_HS (typ) (mOhm) 70
Ron_LS (typ) (mOhm) 70
Iq (typ) (mA) 0.04
Features 100% Duty Cycle;AEC-Q100 Qualified;Adjustable Current Limit;Adjustable Frequency;Adjustable Soft-Start;Current Mode Control;Cycle-by-Cycle Current Limit;Enable Input;External Synchronization;OCP;OTP;Power Good;Selectable (PSM or PWM);UVP
Package Type WET-WQFN4x4-24S
  • AEC-Q100 Grade 1 Qualified
  • Wide Input Voltage Range
    ► 4V to 36V
    ► 3V to 36V (Soft-start is finished)
  • Wide Output Voltage Range : 0.8V to VIN
  • Maximum Output Current : 3A
  • Peak Current Mode Control
  • Integrated 70mΩ Switch and 70mΩ Synchronous Rectifier
  • Low Quiescent Current : 40μA
  • Fast 60ns Minimum Switch On-Time
  • Ultra-Short 65ns Minimum Switch Off-Time
  • Adjustable and Synchronizable Switching : 300kHz to 2.2MHz
  • Selectable PSM/FPWM at Light Load
  • Optional Spread-Spectrum Frequency Modulation for Low EMI
  • Externally Adjustable Soft-Start
  • Power Good Indication
  • Enable Control
  • Adjustable Output Voltage with Cable Drop Compensation
  • Constant Current (CC) and Constant Voltage (CV) Regulation
  • 0.8V ± 1.5% CV Reference Accuracy
  • Adjustable Current Limit
  • Adjacent Pin-Short Protection
  • Built-In UVLO, UVP, OTP
TitleLast UpdateShareDownload
36VIN, 3A, High Efficiency Synchronous Step-Down Converter with Low Quiescent Current2019/07/17
Technical Documents
TitleLast UpdateShareDownload
Richtek Selection Guide [Oct., 2020]2020/12/30
Reference Design
TitleLast UpdateShareDownload
Richtek Load Transient Tool2021/01/21
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RTQ2105GQWT-QAWET-WQFN4x4-24S1500 Not available Buy from Distributor