XRP6124

Non-Synchronous PFET Step-Down Controller
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Overview

Information Non-Synchronous PFET Step-Down COT Controller
Max Rec. Output Current (A) 5
IQ (µA) 500
VIN MIN (V) 3
VIN MAX (V) 30
VOUT MIN (V) 1.2
VOUT MAX (V) 16
Frequency (kHz) 200-1000
Efficiency (%) 92
Control Mode Proprietary emulated current mode COT
Special Features Light Load PFM, Enable, Thermal Shutdown, UVLO, Internal 5V VCC, Soft Start Built-in, Internal Compensation
Operating Temp Range (°C) -40 to 125
Package SOT23-5
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The XRP6124 is a non synchronous step-down (buck) controller for up to 5Amps point-of-loads. A wide 3V to 30V input voltage range allows for single supply operations from industry standard 3.3V, 5V, 12V and 24V power rails.

With a proprietary Constant On-Time (COT) control scheme, the XRP6124 provides extremely fast line and load transient response while the operating frequency remains nearly constant. It requires no loop compensation hence simplifying circuit implementation and reducing overall component count. The XRP6124 also implements an emulated ESR circuitry allowing usage of ceramic output capacitors and insuring stable operations without the use of extra external components.

Built in soft-start prevents high inrush currents while under voltage lock-out and output short-circuit protections insure safe operations under abnormal operating conditions.

The XRP6124 supports input voltages up to 18V while the XRP6124HV supports input voltages up to 30V. Both options are available in a RoHS compliant, green/halogen free space-saving 5-pin SOT23 package.

  • 5A point-of-load capable step-down controller
    • Down to 1.2V output voltage conversion
  • Wide input voltage range
    • 3V to 18V: XRP6124
    • 4.5V to 30V: XRP6124HV
  • Constant on-time operations – 500ns
    • Up to 1MHz constant frequency operations
    • No external compensation
    • Supports ceramic output capacitors
  • Fast transient response
  • Built-in 2ms soft-start
  • Short circuit protection
  • <1µA shutdown current
  • RoHS Compliant, Green/Halogen Free 5-pin SOT23 package

  • Point-of-load conversions
  • Audio-video equipment
  • Industrial and medical equipment
  • Distributed power architecture

Documentation & Design Tools

Type Title Version Date File Size
Data Sheets XRP6124 Non-Synchronous PFET Step-Down Controller 1.1.1 July 2018 515.3 KB
Application Notes AN200, Downloading and Installing CAD Symbols and Footprints with Ultra Librarian April 2019 1.2 MB
User Guides & Manuals XRP6124 Evaluation Board Manual 1.0.0 January 2011 812.9 KB
Product Brochures Power Management Brochure October 2020 2.4 MB
Symbols & Footprints XRP6124ESTR0.5-F CAD File (.bxl) September 2018 81.7 KB
Symbols & Footprints XRP6124HVESTR0.5-F CAD File (.bxl) September 2018 81.7 KB
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Quality & RoHS

Part Number RoHS | Exempt RoHS Halogen Free REACH TSCA MSL Rating / Peak Reflow Package
XRP6124ESTR0.5-F N Y Y Y Y L1 / 260ᵒC SOT-23-5
XRP6124HVESTR0.5-F N Y Y Y Y L1 / 260ᵒC SOT-23-5

Click on the links above to download the Certificate of Non-Use of Hazardous Substances.

Additional Quality Documentation may be available, please Contact Support.

Parts & Purchasing

Part Number Pkg Code Min Temp Max Temp Status Suggested Replacement Buy Now Order Samples PDN
XRP6124ES0.5-F SOT-23-5 -40 125 OBS XRP6124ESTR0.5-F
XRP6124ESTR0.5-F SOT-23-5 -40 125 Active Order
XRP6124HVES0.5-F SOT-23-5 -40 125 OBS XRP6124HVESTR0.5-F
XRP6124HVESTR0.5-F SOT-23-5 -40 125 Active Order
XRP6124EVB Board Active
XRP6124HVEVB Board Active
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Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.

Packaging

Pkg Code Details Quantities Dimensions PDF
SOT-23-5
  • JEDEC Reference: MO-178
  • MSL Pb-Free: L1 @ 260ºC
  • MSL SnPb Eutectic: n/a
  • ThetaJA: 191ºC/W
  • Bulk Pack Style: Canister
  • Quantity per Bulk Pack: n/a
  • Quantity per Reel: 3000
  • Quantity per Tube: n/a
  • Quantity per Tray: n/a
  • Reel Size (Dia. x Width x Pitch): 180 x 8 x 12
  • Tape & Reel Unit Orientation: 3 Pins at sprocket hole.
  • Dimensions: mm
  • Length: 2.90
  • Width: 1.60
  • Thickness: 1.45
  • Lead Pitch: 0.95

Notifications

Distribution Date Description File
01/25/2024 To improve manufacturing efficiency, MaxLinear has qualified the leadframes from AAMI in Chuzhou in addition to the currently qualified AAMI factories in Shenzhen and Malaysia, for use on the products listed above. There is no change to form, fit, function and reliability of the parts.
02/16/2018 Standard tape and reel quantity will change from 2500 pieces to 3000 pieces for SOT23-3L/5L/6L. Addendum: Remove SOT-89 parts from affected products list.
07/11/2017 Product Discontinuation Notification
01/30/2017 Qualification of alternate assembly subcon, JCET.
01/12/2017 Standard tape and reel quantity will change from 2500 pieces to 3000 pieces for SOT23-3L/5L/6L.
07/30/2013 Addition of an alternate qualified assembly supplier, Carsem (Malaysia) for SOT23 package using copper wire bonding. Material Change.

FAQs & Support

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The -F suffix indicates ROHS / Green compliance:
https://www.exar.com/quality-assurance-and-reliability/lead-free-program

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The COT families (XRP6141, XRP6124 and XR75100 controllers, XR76xxx regulators and XR79xxx power modules) have 2 modes of operation that can be set: DCM / CCM (discontinuous conduction mode / continuous conduction mode) or FCCM (Forced CCM) mode. In FCCM mode, the converter operates at a preset frequency regardless of output current. In DCM / CCM mode the converter operates in DCM or CCM depending on the Iout magnitude. If Iout < ½ Ipp, the converter transitions to DCM mode. If Iout is higher, operation is in CCM mode.

The main advantage of DCM / CCM is that it provides significantly higher efficiency at light loads. For those applications where that doesn’t matter, FCCM can be used and has the advantage that it allows for operation at a constant frequency, regardless of load. It also results in lower Vout ripple, and will operate in an inaudible range.

There are many factors to consider in selecting the inductor including core material, inductance versus frequency, current handling capability, efficiency, size and EMI. Typically, the inductor is primarily chosen for value, saturation current and DC resistance (DCR). Increasing the inductor value will decrease output voltage ripple, but degrade transient response. Low inductor values provide the smallest size, but cause large ripple currents, poor efficiency and require more output capacitance to smooth out the larger ripple current. The inductor must be able to handle the peak current at the switching frequency without saturating, and the copper resistance in the winding should be kept as low as possible to minimize resistive power loss. A good compromise between size, loss and cost is to set the inductor ripple current to be within 20% to 40% of the maximum output current.

 

The switching frequency and the inductor operating point determine the inductor value as follows:

 

L = Vout x (Vinmax – Vout) / Vinmax x fs x Kr x Ioutmax

 

Where fs = switching frequency

Kr = ratio of the AC inductor ripple current to the maximum output current

 

So for example, we want to choose L for the XR76108 (Ioutmax 8A) and wish to convert 12Vin to 2.5Vout with a frequency of 1MHz:

 

L = 2.5V x (12V – 2.5V) / 12V x 106 x 35% x 8A = 0.707 uH

 

The peak-to-peak inductor ripple current is:

 

Ipp = Kr x Ioutmax
 

In our example, Ipp = 35% x 8A = 2.8A

 

Once the required inductor value is selected, the proper selection of core material is based on peak inductor current and efficiency requirements. The core must be large enough not to saturate at the peak inductor current.

 

Ipeak = Ioutmax + Ipp/2

In our example, Ipeak = 8A + 2.8A/2 = 9.4A

 
and provide lower core loss at the high switching frequency. Low cost powered-iron cores have a gradual saturation characteristic but can introduce considerable AC core loss, especially when the inductor value is relatively low and the ripple current is high. Ferrite materials, although more expensive, have an abrupt saturation characteristic with the inductance dropping sharply when the peak design current is exceeded. Nevertheless, they are preferred at high switching frequencies because they present very low core loss while the designer is only required to prevent saturation. In general, ferrite or molypermalloy materials are a better choice for all but the most cost sensitive applications.

See Application Note ANP-20 (Properly Sizing MOSFETs for PWM Controllers).

In general, it is set for Imax x 1.5. It would be close the maximum Iout (including ripple). If conservatively set too high, the hiccup mode may not be activated fast enough. If set too low, the ripple could cause the current to go over the threshold and set it into hiccup on a pre-mature basis.

 

The datasheets have an equation that calculates the Rlim resistor value to be used to program the Iocp. Also, a graph of Iocp vs. I lim is shown in the datasheet.

A zero-cross comparator monitors the voltage across the low-side FET when it is on. The comparator threshold is nominally set at -1mV or -2mV (see individual datasheet). If there is sufficient IOUT such that VSW is below the threshold and therefore does not trigger the zero-cross comparator, CCM operation continues.

 

As IOUT is reduced, VSW gets closer to ground. When VSW meets the threshold, the zero-cross comparator triggers. If there are 8 consecutive triggers, then DCM operation begins. The low side FET is turned off when IL x RDS equals the zero-cross threshold.

 

As there is no negative inductor current, the charge transferred to COUT is preserved. As IOUT decreases further, less charge transfer to COUT is required. Pulses grow further apart, frequency is reduced and efficiency increases.

 

DCM persists as long as there are 8 consecutive zero-crosses.

 

Note that when the DCM frequency falls below about 1kHz, the controller turns on the lower-side FET for 100ns once every 1.2ms to refresh the charge on the bootstrap capacitor. This refresh cycle generates small spikes on SW, which can be seen interlaced between DCM pulses.