300mA High Efficiency Quiescent Current Synchronous Buck Regulator Wit
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Document Number: 34726 Rev. 1.0, 5/2008
300mA High Efficiency Quiescent Current Synchronous Buck Regulator With Z-mode
34726 high efficiency, quiescent current (IQ), synchronous buck regulator, implementing Freescale's innovative Z-mode architecture. Freescale's Z-mode architecture greatly improves ripple performance during light load currents, still maintains quiescent current 65uA, load "Sleepy" Z-mode. 34726 accepts input voltage range 5.5V, making ideally suited single cell Li-Ion based applications. Factory preset output voltages, ranging from 0.8V 3.3V, reduce number required auxiliary components. part able provide 300mA continuous load current across input output voltage ranges. 34726 switches 2.0MHz allow small, surface mount inductors capacitors save precious board space. 34726 available small, space saving, cost, UDFN-8 packages. part guaranteed operation over -25°C 85°C temperature range. Features peak efficiency 2.0MHz switching frequency 2.7V 5.5V input voltage range Automatic transition energy saving light load Z-mode (low ripple) Fixed output voltage options from 3.3V 65µA quiescent current during sleepy Z-mode 300mA maximum continuous output current Internal 2.0ms soft start Thermal over-current protection 0.1µA quiescent current shutdown (disabled) Ultra thin UDFN package Pb-free packaging designated suffix code 34726 2.7V 5.5V
34726
POWER MANAGEMENT
Bottom View
SUFFIX (PB-FREE) 98ASA10787D 8-PIN UDFN
ORDERING INFORMATION
Device MC34726AFC/R2 MC34726BFC/R2 MC34726CFC/R2 -25°C 85°C 8-UDFN Temperature Range (TA) Package
3.3V 300mA
COUT *Programmable table
Figure 34726 Typical Operating Circuit
This document contains certain information product. Specifications information herein subject change without notice.
Freescale Semiconductor, Inc., 2008. rights reserved.
DEVICE VARIATIONS
DEVICE VARIATIONS
Table Device Variations
Freescale Part MC34726AFC MC34726BFC MC34726CFC Range 5.5V 5.5V 5.5V Output Voltage(1) 1.2V 1.8V 3.3V Maximum Load Current 300mA 300mA 300mA Switch Frequency (MHz)(2)
Notes Output voltages 0.8V, 0.9V, 1.0V, 1.1V, 1.3V, 1.4V, 1.5V, 1.85V, 2.0V, 2.5V options available request. Contact Freescale sales. Factory programmable 2.0MHz 4.0Mhz. Contact Freescale sales availability 4.0MHz functionality.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
INTERNAL BLOCK DIAGRAM
INTERNAL BLOCK DIAGRAM
Osc. Internal Regulator Ref. Buck Controller Thermal Shutdown Current Limit Ref. UVLO Soft Start
Figure 34726 Simplified Internal Block Diagram
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
CONNECTIONS
CONNECTIONS
UDFN-8 (Non
Transparent View
Figure 34726 Connections Table 34726 Definitions functional description each found Functional Description section beginning page
Number Name Function Input Ground Ground Input Input Output Output Formal Name Supply Voltage Input Ground Ground Enable Feedback Input Connection Switching Node Switching Node Power input Ground noise ground Active high enable input Feedback output voltage Internally connected. Connect externally This terminal connects output inductor This terminal connects output inductor Definition
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
MAXIMUM RATINGS
Table Maximum Ratings voltages with respect ground unless otherwise noted. Exceeding these ratings cause malfunction permanent damage device.
Ratings ELECTRICAL RATINGS pins voltages Voltage(1) Human Body Model (HBM) Machine Model (MM) THERMAL RATINGS Operating Ambient Temperature Range Storage Temperature Range Maximum Lead Temperature(2),(3) Junction Temperature Operating Junction Temperature Maximum Junction Temperature Thermal Resistance(4) Junction-to-Case Junction-to-Ambient Power Dissipation Continuous (Derate 3.0mW/°C over 70°C) TSTG TPPRT +150 °C/W +150 Note VIN, VEN, VFB, VESD ±2000 ±200 -0.3 Symbol Value Unit
Notes testing performed accordance with Human Body Model (HBM) (CZAP 100pF, RZAP 1500), Machine Model (MM) (CZAP 200pF, RZAP soldering temperature limit seconds maximum duration. designed immersion soldering. Exceeding these limits cause malfunction permanent damage device. Freescale's Package Reflow capability meets Pb-free requirements JEDEC standard J-STD-020C. Peak Package Reflow Temperature Moisture Sensitivity Levels (MSL). www.freescale.com, search part number [e.g. remove prefixes/suffixes enter core view orderable parts. (i.e. MC33xxxD enter 33xxx), review parametrics. Device mounted Freescale test board JEDEC DESD51-2.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS
STATIC ELECTRICAL CHARACTERISTICS
Table Static Electrical Characteristics Characteristics noted under conditions; 2.7V 5.5V, 0.8V VOUT 3.3V, -25oC 85oC, COUT 4.7µF, 4.7µH (See Figure unless otherwise noted. typical specifications measured following conditions; +25oC, 3.6V, 2.0MHz with typical operating circuit (See Figure unless otherwise noted.
Characteristic Supply Voltage Output Voltage (Factory preset) Output Current Total Supply Current
Symbol VOUT IOUT IDIS
Unit
Regulator disabled Quiescent Current (Switching) Sleepy Z-mode ILOAD Current Limit Current rising high side Output Voltage Accuracy output voltage) Over load temperature UVLO Threshold(6) VIN: -5.5V rising falling Enable Voltage Regulator operating Regulator shutdown High Side Power MOSFET Resistance 3.6V, VOUT 1.8V, 40°C, ILOAD 150mA Side Power MOSFET Resistance 3.6V, VOUT 1.8V, 40°C, ILOAD 150mA Load Regulation ILOAD 300mA VOUT 1.8V Line Regulation 2.7V 5.5V Start-up Overshoot output voltage) ILOAD 0mA, VOUT 1.8V COUT 4.7µF Thermal Shutdown Threshold (Junction Temperature) Thermal Shutdown Hysteresis (Junction Temperature) Notes Maximum IDIS measured 3.6V 25°C. TSTDN THYSTR VSTO VOUT/VIN VOUT/IOUT RDS(ON)L RDS(ON)H VUVLO VOUT
VOUT
VOUT
product with VOUT 3.3V minimum less than 3.6V, VOUT value will track (drop below 3.3V) down value 2.5V, where UVLO shutdown mechanism will activate.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS
DYNAMIC ELECTRICAL CHARACTERISTICS
Table Dynamic Electrical Characteristics Characteristics noted under conditions; 2.7V 5.5V, 0.8V VOUT 3.3V, -20oC 85oC, COUT 4.7µF, 4.7µH (See Figure unless otherwise noted. typical specifications measured following conditions; +25oC, 3.6V, 2.0MHz with typical operating circuit (See Figure unless otherwise noted.
Characteristic Switching Frequency
Symbol DMAX
Unit
Maximum Duty Cycle
Measured from Internal Soft-start Timer VOUT Rise Time Notes factory programmed ±20% nominal 2.0MHz. maximum duty limits range output voltages achievable given input voltage.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES
ELECTRICAL PERFORMANCE CURVES
Efficiency
VIN=2.7V VIN=3.6V VIN=5.5V
(10V/DIV) Time: 500µs/DIV VOUT (200mV/DIV)
(200mA/DIV)
ILOAD (mA)
1000
Figure Start-up Response ILOAD 0mA, VOUT=1.2V Time: 100µs/DIV VOUT (1V/DIV) (2V/DIV)
Figure Efficiency Load Current 3.6V, VOUT 1.8V, TA=25oC
1.00 Line Regulation 0.75 0.50 0.25 0.00 -0.25
ILOAD=0mA ILOAD=100mA ILOAD=300mA
(200mA/DIV)
Figure Line Regulation 2.7V 5.5V VOUT 1.8V, TA=25oC
Figure Sleepy Z-ModeSwitching Waveforms 3.6V, VOUT 1.8V ILOAD 1.0mA Time: 5µs/DIV VOUT (1V/DIV)
0.75 Load Regulation 0.50 0.25 0.00 -0.25
(2V/DIV)
VIN=2.7V VIN=3.6V VIN=5.5V
(200mA/DIV) Figure Z-ModeSwitching Waveforms 3.6V, VOUT 1.8V ILOAD 10mA
ILOAD (mA)
Figure Load Regulation ILOAD 300mA, VOUT 1.8V
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES
Time: 500ns/DIV
VOUT (1V/DIV) (2V/DIV)
Time: 200µs/DIV
VOUT Coupled, 200mV/DIV) (2V/DIV)
ILOAD (200mA/DIV)
(200mA/DIV) Figure Switching Waveforms 3.6V, VOUT 1.8V ILOAD 150mA Time: 200µs/DIV VOUT Coupled, 500mV/DIV) Time: 200µs/DIV (2V/DIV) VOUT Coupled, 50mV/DIV) (2V/DIV)
Figure Load Transient Z-ModeVIN 3.6V, ILOAD =10mA 300mA
ILOAD (100mA/DIV)
ILOAD (100mA/DIV)
Figure Load Transient Sleepy Z-ModeVIN 3.6V, ILOAD =1mA 150mA
Figure Load Transient 3.6V, ILOAD 150mA 300mA
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
FUNCTIONAL DESCRIPTION INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
34726 high efficiency, synchronous, buck regulator, utilizing voltage mode control architecture with feed forward. capable providing 300mA load current output voltages 0.8V 3.3V, from single input voltage rail between 2.7V 5.5V. buck converter, most losses high output loads conduction losses power train, light output loads, conduction losses reduced most losses become switching losses. Using Freescale's Zmode architecture, 34726, light output loads, will smoothly transition into lower switching frequency, thus improving efficiency.
FUNCTIONAL DESCRIPTION SUPPLY VOLTAGE INPUT (VIN)
2.7V 5.5V power input. Bypass with 4.7µF ceramic capacitor close possible pins.
FEEDBACK INPUT (FB)
Feedback output voltage.
GROUND (GND)
Ground.
SWITCHING NODE (SW)
This terminal connects output inductor. node internally connects drain both high side MOSFET side MOSFET.
ENABLE (EN)
Active high enable input. over-voltage protected 6.0V, independent supply voltage. Drive with logic high signal connect VIN) normal operation. Drive with logic signal, connect will disable 34726.
CONNECTION (NC)
Internally connected. Connect externally.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
MC34726 Functional Block Diagram Integrated Supply Internal Regulator Reference Oscillator Control Thermal Shutdown Undervoltage Lockout Soft Start Current Limit Power MOSFET
Power MOSFET Driver
Integrated Supply Oscillator Control MOSFET
Figure 34726 Functional Internal Block Diagram
INTEGRATED SUPPLY INTERNAL REGULATOR REFERENCE
internal regulator reference block steps down high input voltage lower voltage, power internal blocks, provides reference voltage other internal blocks.
soft-start sequence also occurs upon recovery from fault condition.
UVLO
UVLO block monitors input voltage. Once input voltage lower than falling threshold voltage, this block turns device, avoid unpredictable circuit behavior.
OSCILLATOR
oscillator block provides 2.0MHz clock signal controller.
CURRENT LIMIT
current limit block monitors inductor current. When peak inductor current reaches current limit, this block turns high side MOSFET, prevent device external components from damage.
CONTROLLER THERMAL SHUTDOWN
thermal shutdown block monitors temperature. Once temperature reaches threshold, this block turns device prevent further temperature rise.
POWER-MOSFET DRIVER
power-MOSFET-driver block controls phase diver signals enhances drive capability these
POWER-MOSFET
power-MOSFET block contains power MOSFETs. PMOS that passes current from input output, other NMOS that provides inductor current loop when PMOS turned off.
SOFT-START
soft-start block controls output voltage ramp after device enabled, limit in-rush current. start-up time internally approximately 2.0ms, independent input voltage, output voltage, load current.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES Z-MODE OPERATION
34726 operates typical fixed frequency, regulator, moderate heavy load currents. load decreased, such that operation transitions from continuous conduction mode (CCM) discontinuous conduction mode (DCM), duty cycle reduced until approaches full load duty cycle. this point 34726 transitions into Z-mode operation, where Z-mode Factor 0.85. Zmode, regulator skips pulses whenever duty cycle below duty cycle. load decreases, this pulse skipping reduces switching frequency switching losses thus improving efficiency. example, light load demanded duty cycle 2.0MHz, with Zmode this same load will require only (0.3/0.85)2 2.0MHz 0.249MHz switching frequency, hence switching losses will reduced almost fold. Figure illustrates transition exit from Zmode.
VZERR VRAMP
PWM_Ref. Factor
Time
Figure Z-mode Operation
SLEEPY Z-MODE OPERATION
improve current efficiency, 34726 transitions into Sleepy Z-mode load currents approximately 1.0mA lower. This accomplished powering down
internal circuit blocks lower device's quiescent current. Additionally, oscillator frequency drops 250kHz side switch turned emulate operation asynchronous buck converter.
DETAILED FUNCTIONAL DEVICE OPERATION OVER-CURRENT PROTECTION
34726 implements layers protection during overload conditions. first current limit feature prevent device external components from damage. When peak inductor current reaches over-current limit, nominally 450mA, high side MOSFET turns provide cycle cycle protection. over-current condition persists temperature surpasses overtemperature protection (OTP) threshold, this second layer protection shuts down device.
SHORT-CIRCUIT PROTECTION
When short-circuit condition occurs output, typical regulators will tend operate maximum duty cycle. This condition saturate inductor produce severe peak currents, resulting damage device. 34726 avoids this scenario detecting output voltages below 0.5V. Upon detection, part re-starts continuously until short circuit condition removed, part surpasses threshold.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES
OVER-TEMPERATURE PROTECTION
limit operating temperature, 34726 shuts down junction temperature switching MOSFET surpasses 140°C. junction temperature subsequently drops 130°C, 34726 re-starts.
soft-start sequence also occurs upon recovery from fault condition.
UNDER-VOLTAGE LOCK-OUT
UVLO threshold 2.7V rising VIN, 2.5V falling VIN. VOUT 3.3V, VOUT value will track below 3.6V until 2.5V falling threshold reached. UVLO falling threshold met, part shuts down will power again with soft-start, when UVLO rising threshold surpassed.
SOFT-START OPERATION
limit in-rush current, internal timer controls output voltage ramp after part enabled. start-up time internally approximately 2.0ms independent input voltage, output voltage, load current.
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
TYPICAL APPLICATIONS APPLICATION INFORMATION
TYPICAL APPLICATIONS
APPLICATION INFORMATION INPUT CAPACITOR
input capacitor used minimize input voltage transient that cause instability when load transient current high. Typically 4.7µF ceramic capacitor sufficient most applications. Depending load transient current, larger capacitance required.
INDUCTOR SELECTION
4.7µH resistance inductor typically used 34726 guarantee system stable operation.
OUTPUT CAPACITOR
stable operation output voltage ripple, ceramic capacitor 4.7µF minimum value needed.
TYPICAL APPLICATIONS 1.2V OUTPUT DC/DC CONVERTOR
Figure shows typical application using 34726A. COUT typically 4.7µF/X5R ceramic capacitors. typically 4.7µH resistance inductor. connects output directly monitoring output voltage. Normally, connects input supply directly enable regulator.
34726A 2.7V 5.5V 4.7µF
4.7µH COUT 4.7µF 1.2V 300mA
Figure 1.2V/300mA DC/DC convertor
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
TYPICAL APPLICATIONS PACKAGE DIMENSIONS
PACKAGE DIMENSIONS
most current package revision, visit www.freescale.com perform keyword search using "98A" listed below.
SUFFIX 12-PIN 98ASA10787D REVISION
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
TYPICAL APPLICATIONS PACKAGE DIMENSIONS
SUFFIX 12-PIN 98ASA10787D REVISION
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
TYPICAL APPLICATIONS PACKAGE DIMENSIONS
SUFFIX 12-PIN 98ASA10787D REVISION
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
REVISION HISTORY
REVISION HISTORY
REVISION
DATE 5/2008
DESCRIPTION CHANGES Initial Release
34726
Analog Integrated Circuit Device Data Freescale Semiconductor
Reach
Home Page: www.freescale.com Support: USA/Europe Locations Listed: Freescale Semiconductor, Inc. Technical Information Center, EL516 2100 East Elliot Road Tempe, Arizona 85284 +1-800-521-6274 +1-480-768-2130 www.freescale.com/support Europe, Middle East, Africa: Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 81829 Muenchen, Germany 1296 (English) 52200080 (English) 92103 (German) (French) www.freescale.com/support Japan: Freescale Semiconductor Japan Ltd. Headquarters ARCO Tower 1-8-1, Shimo-Meguro, Meguro-ku, Tokyo 153-0064 Japan 0120 191014 5437 9125 support.japan@freescale.com Asia/Pacific: Freescale Semiconductor Hong Kong Ltd. Technical Information Center King Street Industrial Estate N.T., Hong Kong +800 2666 8080 support.asia@freescale.com Literature Requests Only: Freescale Semiconductor Literature Distribution Center P.O. 5405 Denver, Colorado 80217 1-800-441-2447 303-675-2140 Fax: 303-675-2150
Information this document provided solely enable system software implementers Freescale Semiconductor products. There express implied copyright licenses granted hereunder design fabricate integrated circuits integrated circuits based information this document. Freescale Semiconductor reserves right make changes without further notice products herein. Freescale Semiconductor makes warranty, representation guarantee regarding suitability products particular purpose, does Freescale Semiconductor assume liability arising application product circuit, specifically disclaims liability, including without limitation consequential incidental damages. "Typical" parameters that provided Freescale Semiconductor data sheets and/or specifications vary different applications actual performance vary over time. operating parameters, including "Typicals", must validated each customer application customer's technical experts. Freescale Semiconductor does convey license under patent rights rights others. Freescale Semiconductor products designed, intended, authorized components systems intended surgical implant into body, other applications intended support sustain life, other application which failure Freescale Semiconductor product could create situation where personal injury death occur. Should Buyer purchase Freescale Semiconductor products such unintended unauthorized application, Buyer shall indemnify hold Freescale Semiconductor officers, employees, subsidiaries, affiliates, distributors harmless against claims, costs, damages, expenses, reasonable attorney fees arising directly indirectly, claim personal injury death associated with such unintended unauthorized use, even such claim alleges that Freescale Semiconductor negligent regarding design manufacture part. Freescaleand Freescale logo trademarks Freescale Semiconductor, Inc. other product service names property their respective owners. Freescale Semiconductor, Inc., 2008. rights reserved.
34726 Rev. 5/2008
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