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Microchip Technology MIC2125 General Description Manual
Microchip Technology MIC2125 General Description Manual

Microchip Technology MIC2125 General Description Manual

28v synchronous buck controllers featuring adaptive on-time control

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Featuring Adaptive ON-Time Control
Features
• Hyper Speed Control Architecture Enables:
- High delta V operation (V
= 0.6V)
- Any Capacitor™ stable
• 4.5V to 28V Input Voltage
• Adjustable Output Voltage from 0.6V to 24V
• 200 kHz to 750 kHz Programmable Switching
Frequency
®
• HyperLight Load
(MIC2125)
®
• Hyper Speed Control
(MIC2126)
• Enable Input and Power Good Output
• Built-in 5V Regulator for Single-Supply Operation
• Programmable current limit and "hiccup" mode
short-circuit protection
• 7 ms internal soft-start, internal compensation,
and thermal shutdown
• Supports Safe Start-Up into a Prebiased Output
• –40°C to +125°C Junction Temperature Range
• Available in 16-pin, 3 mm × 3 mm QFN Package
Applications
• Networking/Telecom Equipment
• Base Stations, Servers
• Distributed Power Systems
• Industrial Power Supplies
 2015 Microchip Technology Inc.
28V Synchronous Buck Controllers
= 28V and V
IN
OUT
MIC2125/6
General Description
The MIC2125 and MIC2126 are constant-frequency
synchronous buck controllers featuring a unique
adaptive ON-time control architecture. The MIC2125/6
operate over an input voltage range from 4.5V to 28V
and can be used to supply load current up to 25A. The
output voltage is adjustable down to 0.6V with a
guaranteed accuracy of ±1%. The device operates with
programmable switching frequency from 200 kHz to
750 kHz.
®
HyperLight Load
architecture provides the same high
efficiency and ultra-fast transient response as the
®
Hyper Speed Control
architecture under medium to
heavy loads. It also maintains high efficiency under
light load conditions by transitioning to variable
frequency, discontinuous conduction mode operation.
The MIC2125/6 offer a full suite of features to ensure
protection of the IC during fault conditions. These
include undervoltage lockout to ensure proper
operation
under
power-sag
soft-start to reduce inrush current, "hiccup" mode
short-circuit protection, and thermal shutdown.
Package Type
MIC2125/6
16-Pin 3 mm x 3 mm QFN (ML)
16
15
VDD
1
PVDD
2
EP 17
ILIM
3
DL
4
5
6
conditions,
internal
14
13
AGND
12
NC
11
10
OVP
BST
9
7
8
DS20005459B-page 1

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Summary of Contents for Microchip Technology MIC2125

  • Page 1 • Programmable current limit and “hiccup” mode frequency, discontinuous conduction mode operation. short-circuit protection The MIC2125/6 offer a full suite of features to ensure • 7 ms internal soft-start, internal compensation, protection of the IC during fault conditions. These and thermal shutdown include undervoltage lockout to ensure proper •...
  • Page 2 ×2 ESTIMATE MODIFIED UVLO 0.1μF 0.72μH 100kΩ 3.3V/20A CONTROL PVDD LOGIC 470pF TIMER 90.9kΩ 470μF 10kΩ SOFT–START 100μF 1.2kΩ 0.1μF PGND SOFT START 2.26kΩ DETECTION THERMAL SHUTDOWN COMPENSATION COMP 0.6V 49.9kΩ 0.6V AGND  2015 Microchip Technology Inc. DS20005459B-page 2...
  • Page 3 ‡ Notice: The device is not guaranteed to function outside its operating ratings. Note 1: Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5 kΩ in series with 100 pF.  2015 Microchip Technology Inc. DS20005459B-page 3...
  • Page 4 Current-Limit Source Current = 0.6V Specification for packaged product only. Note 1: The application is fully functional at low V (supply of the control section) if the external MOSFETs have low voltage V  2015 Microchip Technology Inc. DS20005459B-page 4...
  • Page 5 — — °C — Hysteresis Specification for packaged product only. Note 1: The application is fully functional at low V (supply of the control section) if the external MOSFETs have low voltage V  2015 Microchip Technology Inc. DS20005459B-page 5...
  • Page 6 (i.e., T ). Exceeding the maximum allowable power dissipation will cause the device operating junction temperature to exceed the maximum +125°C rating. Sustained junction temperatures above +125°C can impact the device reliability.  2015 Microchip Technology Inc. DS20005459B-page 6...
  • Page 7 Note: Unless otherwise noted, V = 12V, FREQ = 350 kHz. FIGURE 2-1: Operating Supply FIGURE 2-4: Shutdown Current vs. Current vs. Input Voltage (MIC2125). Input Voltage (MIC2125). FIGURE 2-2: Feedback Voltage vs. Input FIGURE 2-5: Switching Frequency vs. Voltage (MIC2125).
  • Page 8 Note: Unless otherwise noted, V = 12V, FREQ = 350 kHz. FIGURE 2-7: Voltage vs. Input FIGURE 2-10: Operating Supply Voltage (MIC2125). Current vs. Temperature (MIC2125). FIGURE 2-11: Feedback Voltage vs. FIGURE 2-8: Enable Threshold vs. Input Temperature (MIC2125). Voltage (MIC2125).
  • Page 9 EN Bias Current vs. Temperature (MIC2125) Temperature (MIC2125) FIGURE 2-14: UVLO Threshold vs. FIGURE 2-17: Voltage vs. Temperature (MIC2125) Temperature (MIC2125) FIGURE 2-15: Enable Threshold vs. FIGURE 2-18: Current-Limit Source Temperature (MIC2125). Current vs. Temperature (MIC2125)  2015 Microchip Technology Inc. DS20005459B-page 9...
  • Page 10 = 12V, FREQ = 350 kHz. *Note: For Case Temperature graphs: The temperature measurement was taken at the hottest point on the MIC2125/6 case mounted on a 5 square inch PCBn. Actual results will depend upon the size of the PCB, ambient temperature and proximity to other heat emitting components.
  • Page 11 = 12V, FREQ = 350 kHz. *Note: For Case Temperature graphs: The temperature measurement was taken at the hottest point on the MIC2125/6 case mounted on a 5 square inch PCBn. Actual results will depend upon the size of the PCB, ambient temperature and proximity to other heat emitting components.
  • Page 12 (10V/div) = 1.2V = 12V (2V/div) = 20A = 1.2V = 20A (10V/div) (1V/div) (2V/div) (20A/div) (20A/div) Time (10ms/div) Time (4ms/div) FIGURE 2-36: Enable Turn-On Delay and FIGURE 2-33: Soft Turn-Off. Rise Time.  2015 Microchip Technology Inc. DS20005459B-page 12...
  • Page 13 FIGURE 2-38: Enable Thresholds. = 1.2V = 1A = 12V = 1.2V (2V/div) (500mV/div) (10A/div) (500mV/div) Time (20ms/div) Time (20ms/div) FIGURE 2-42: Output Peak Current-Limit FIGURE 2-39: Enable Turn-On Delay and Threshold. Rise Time.  2015 Microchip Technology Inc. DS20005459B-page 13...
  • Page 14 = 12V = 1.2V (AC-coupled) = 1.2V = 2.5A = 0.1A (500mV/div) (5V/div) (2A/div) (5V/div) Time (4μs/div) Time (2ms/div) FIGURE 2-45: Output Recovery from FIGURE 2-48: MIC2125 Switching Thermal Shutdown. Waveform, I = 0.1A.  2015 Microchip Technology Inc. DS20005459B-page 14...
  • Page 15 = 1.2V = 0A = 0A (2A/div) (5V/div) (10V/div) (1V/div) (10V/div) (5V/div) (5V/div) Time (4μs/div) Time (20ms/div) FIGURE 2-51: MIC2125 Switching FIGURE 2-54: Power Good at V Soft Waveform, I = 0A. Turn-Off.  2015 Microchip Technology Inc. DS20005459B-page 15...
  • Page 16 4.5V to 28V. A 1 μF ceramic capacitor from V to A is required for decoupling. Exposed Pad. Connect the exposed pad to the A copper plane to improve the thermal performance.  2015 Microchip Technology Inc. DS20005459B-page 16...
  • Page 17 4.5V to 28V and their output is adjustable with an external resistive divider. An adaptive ON-time control It is not recommended to use MIC2125/6 with an scheme is employed to obtain a constant switching OFF-time close to t during steady-state frequency and to simplify the control compensation.
  • Page 18 (MIC2125 Only) The MIC2125 operates in discontinuous conduction mode at light load. The MIC2125 has a zero crossing comparator (ZC detection) that monitors the inductor current by sensing the voltage drop across the low-side MOSFET during its ON-time. If the V >...
  • Page 19 -------------------- Circuit NLIM   DS ON In each switching cycle of the MIC2125/6 converter, the Where: inductor current is sensed by monitoring the voltage across the low-side MOSFET during the OFF period. Negative Current Limit NLIM An internal current source of 36 µA generates a voltage...
  • Page 20 Turn-on turn-off transition times approximated by: EQUATION 5-5:          SW HS HSD PULL UP – HS GATE ---------------------------------------------------------------------------------------------------------- - – FIGURE 5-2: Switching Frequency vs.  2015 Microchip Technology Inc. DS20005459B-page 20...
  • Page 21 Smaller peak-to-peak ripple current requires a larger core material and minimizing the winding resistance. inductance value and therefore a larger and more The high-frequency operation of the MIC2125/6 expensive inductor. requires the use of ferrite materials. Lower cost iron A good compromise between size, loss, and cost is to...
  • Page 22 IN(ESR) Value As described in the Theory of Operation subsection of Functional Description, the MIC2125/26 requires at Peak Inductor Current L(PK) least 20 mV peak-to-peak ripple at the FB pin to ensure that the g amplifier and the comparator behave The input capacitor should be qualified for ripple properly.
  • Page 23 20 mV. If the feedback voltage ripple is so EQUATION 5-22: small that the g amplifier and comparator cannot  sense it, then the MIC2125/6 loses control and the ----------------------------- output voltage is not regulated. In order to have – sufficient V ripple, a ripple injection method should be applied for low output voltage ripple applications.
  • Page 24 ESR of the output capacitors. Therefore, additional ripple is injected into the FB pin from the switching node SW via a resistor R and a capacitor C , as shown in Figure 5-7.  2015 Microchip Technology Inc. DS20005459B-page 24...
  • Page 25 • Use a 4.5V V rated MOSFET. Its higher gate threshold voltage is more immune to glitches than a 2.5V or 3.3V rated MOSFET. For more information about the Evaluation board layout, please contact Microchip sales.  2015 Microchip Technology Inc. DS20005459B-page 25...
  • Page 26 MIC2125/6 PACKAGING INFORMATION 16-Lead QFN 3 mm x 3 mm Package Outline and Recommended Land Pattern For the most current package drawings, please see the Microchip Packaging Specification located at Note: http://www.microchip.com/packaging  2015 Microchip Technology Inc. DS20005459B-page 26...
  • Page 27 MIC2125/6 For the most current package drawings, please see the Microchip Packaging Specification located at Note: http://www.microchip.com/packaging  2015 Microchip Technology Inc. DS20005459B-page 27...
  • Page 28 MIC2125/6  2015 Microchip Technology Inc. DS20005459B-page 28...
  • Page 29 Revision A (November 2015) • Original Conversion of this Document. Revision B (December 2015) • Corrected the erroneous listing of the MIC2126 example with a 64LD package. Replaced with cor- rect 16LD package information.  2015 Microchip Technology Inc. DS20005459B-page 29...
  • Page 30 MIC2125/6 NOTES:  2015 Microchip Technology Inc. DS20005459B-page 30...
  • Page 31 Controller featuring Adap- Speed Control tive On-Time Control with Hyper Speed Control –40°C to +125°C –40°C to +125°C junction Temperature: temperature range, 16LD QFN ML = 16-Pin 3 mm x 3 mm QFN Package:  2015 Microchip Technology Inc. DS2005459B-page 31...
  • Page 32 MIC2125/6 NOTES:  2015 Microchip Technology Inc. DS2005459B-page 32...
  • Page 33 ViewSpan, WiperLock, Wireless DNA, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries.
  • Page 34 Tel: 886-2-2508-8600 Tel: 631-435-6000 China - Xian Tel: 86-29-8833-7252 Fax: 886-2-2508-0102 San Jose, CA Fax: 86-29-8833-7256 Tel: 408-735-9110 Thailand - Bangkok Tel: 66-2-694-1351 Canada - Toronto Fax: 66-2-694-1350 Tel: 905-673-0699 Fax: 905-673-6509 07/14/15  2015 Microchip Technology Inc. DS20005459B-page 34...

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Mic2126