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Document Number: MC34716

Rev 5.0, 4/2012

Freescale Semiconductor

Advance Information

* This document contains certain information on a new product.

Specifications and information herein are subject to change without notice.

1.0 MHz Dual Switch-Mode DDR

Power Supply

The 34716 is a highly integrated, space-efficient, low cost, dual

synchronous buck switching regulator with integrated N-channel

power MOSFETs. It is a high performance point-of-load (PoL) power

supply with its second output having the ability to track an external

reference voltage. it provides a full power supply solution for Double-

Data-Rate (DDR) Memories.

Channel one provides a source only, 5.0 A drive capability, while

channel two can sink and source up to 3.0

A. Both channels are highly

efficient with tight output regulation. With its high current drive

capability, channel one can be used to supply the V

DDQ

to the

memory chipset. The second channel’s ability to track a reference

voltage makes it ideal to provide the termination voltage (V

) for

modern data buses. The 34716 also provides a buffered output

reference voltage (V

REFOUT

) to the memory chipset

The 34716 offers the designer the flexibility of many control,

supervisory, and protection functions to allow for easy implementation

of complex designs. It is housed in a Pb-free, thermally enhanced,

and space efficient 26-pin exposed pad QFN.

Features

•50 m integrated N-channel power MOSFETs

• Input voltage operating range from 3.0 to 6.0 V

• 1% accurate output voltages, ranging from 0.7 to 3.6 V

• The second output tracks 1/2 an external reference voltage

• 1% accurate buffered reference output voltage

• Programmable switching frequency range from 200 kHz to

1.0 MHz

• Programmable soft start timing for channel one

• Over-current limit and short-circuit protection on both channels

• Thermal shutdown

• Output over-voltage and under-voltage detection

• Active low power good output signal

• Active low standby and shutdown inputs.

Figure 1. 34716 Simplified Application Diagram

DUAL SWITCH-MODE DDR POWER

SUPPLY

EP SUFFIX

98ASA10728D

26-PIN QFN

34716

ORDERING INFORMATION

Device

Temperature

Range (T

)

Package

MC34716EP/R2 -40 to 85 °C 26 QFN

VIN

PVIN1

3.0 V to 6.0 V

BOOT1

SW1

COMP1

VOUT1

VREFOUT

GND

VREFIN

VDDI

FREQ

STBY

34716

MCU

DDR Memory

Controller

DDR Memory

Chipset

Memory Bus

Termination

DDQ

VDDQ

REF

PGND1

PVIN2

BOOT2

SW2

INV2

COMP2

VOUT2

PGND2

DDQ

ILIM1

INV1

Resistors

Summary of content (27 pages)

PAGE 1
Freescale Semiconductor Advance Information Document Number: MC34716 Rev 5.0, 4/2012 1.0 MHz Dual Switch-Mode DDR Power Supply 34716 The 34716 is a highly integrated, space-efficient, low cost, dual synchronous buck switching regulator with integrated N-channel power MOSFETs. It is a high performance point-of-load (PoL) power supply with its second output having the ability to track an external reference voltage. it provides a full power supply solution for DoubleData-Rate (DDR) Memories.
PAGE 2
INTERNAL BLOCK DIAGRAM INTERNAL BLOCK DIAGRAM STBY PG System Reset M1 System Control Oscillator FREQ SD Buck Control Logic Thermal Monitoring Discharge VBG Bandgap Regulator ILIM2 ISENSE2 ISENSE1 Current Monitoring VDDI Internal Voltage Regulator ILIM1 ILIM1 VIN BOOT1 M2 PVIN1 BOOT2 M3 PVIN2 VIN VIN M4 SW1 M6 Gate Driver ISENSE FSW FSW Gate I Driver SENSE M5 M7 – – + + – + PGND2 Error Amplifier – VBG INV1 COMP2 INV2 M8 M9 Discharge Discharge CHANNEL 1 CHANNE
PAGE 3
PIN CONNECTIONS ILIM1 NC FREQ VIN VIN GND VDDI STBY PIN CONNECTIONS 26 25 24 23 22 21 20 19 BOOT1 1 18 BOOT2 PVIN1 PVIN2 2 17 PVIN1 SW1 SW1 PGND1 Transparent Top View 3 16 PIN 27 SW2 SW2 PGND2 4 15 PGND1 PGND2 14 VOUT2 8 9 10 11 12 13 VREFIN VREFOUT PG SD INV2 7 COMP2 6 COMP1 5 INV1 VOUT1 PVIN2 Figure 3. 34716 Pin Connections Table 1.
PAGE 4
PIN CONNECTIONS Table 1. 34716 Pin Definitions (continued) A functional description of each pin can be found in the Functional Pin Description section beginning on page 12.
PAGE 5
ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS Table 2. Maximum Ratings All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage to the device. Ratings Symbol Value Unit Input Supply Voltage (VIN) Pin VIN -0.3 to 7.0 V High Side MOSFET Drain Voltage (PVIN1, PVIN2) Pins PVIN -0.3 to 7.0 V Switching Node (SW1, SW2) Pins VSW -0.3 to 7.0 V VBOOT - VSW -0.3 to 7.0 V - -0.3 to 7.
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ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS Table 2. Maximum Ratings (continued) All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage to the device. Ratings Symbol Value Unit RJA 93 °C/W RJMA 32 °C/W RQJB 13.
PAGE 7
ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 3. Static Electrical Characteristics Characteristics noted under conditions 3.0 V  VIN  6.0 V, - 40C  TA  85C, GND = 0 V, unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Typ Max Unit Input Supply Voltage Operating Range VIN 3.0 - 6.
PAGE 8
ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 3. Static Electrical Characteristics (continued) Characteristics noted under conditions 3.0 V  VIN  6.0 V, - 40C  TA  85C, GND = 0 V, unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Low Side N-CH Power MOSFET (M5) RDS(ON)(15) Symbol Min Typ Max Unit RDS(ON)LS1 10 - 50 m RDS(ON)M2 2.0 - 4.
PAGE 9
ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 3. Static Electrical Characteristics (continued) Characteristics noted under conditions 3.0 V  VIN  6.0 V, - 40C  TA  85C, GND = 0 V, unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Typ Max Unit RDS(ON)M3 2.0 - 4.0  ISW -10 - 10 A IPVIN2 -10 - 10 µA AEA - 150 - dB UGBWEA - 3.
PAGE 10
ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS Table 4. Dynamic Electrical Characteristics Characteristics noted under conditions 3.0 V  VIN  6.0 V, - 40C  TA  85C, GND = 0 V, unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Typ Max Unit tRISE1 - 8.0 - ns tFALL1 - 5.
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ELECTRICAL CHARACTERISTICS ELECTRICAL PERFORMANCE CURVES Table 4. Dynamic Electrical Characteristics (continued) Characteristics noted under conditions 3.0 V  VIN  6.0 V, - 40C  TA  85C, GND = 0 V, unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25°C under nominal conditions, unless otherwise noted. Characteristic Symbol Min Typ Max Unit tPGRESET 8.
PAGE 12
FUNCTIONAL DESCRIPTION INTRODUCTION FUNCTIONAL DESCRIPTION INTRODUCTION In modern microprocessor/memory applications, address commands and control lines require system level termination to a voltage (VTT) equal to 1/2 the memory supply voltage (VDDQ). Having the termination voltage at midpoint, the power supply insures symmetry for switching times. Also, a reference voltage (VREF) that is free of any noise or voltage variations is needed for the DDR SDRAM input receiver, VREF is also equal to 1/2 VDDQ.
PAGE 13
FUNCTIONAL DESCRIPTION FUNCTIONAL PIN DESCRIPTION ERROR AMPLIFIER INVERTING INPUT (INV1, INV2) STANDBY INPUT (STBY) Buck converter error amplifier inverting input. Connect the VDDQ voltage (channel 1) to INV1 pin through a resistor divider and connect the VTT voltage (channel 2) directly to INV2 pin. If this pin is tied to the GND pin, the device will be in Standby mode. If left unconnected or tied to the VIN pin, the device will be in Normal mode. The pin has an internal pullup of 1.5 M.
PAGE 14
FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION MC34716 - Functional Block Diagram Internal Bias Circuits System Control and Logic Oscillator Protection Functions Control and Supervisory Functions Tracking and Sequencing 2 x Buck Converter Figure 7. Block Illustration INTERNAL BIAS CIRCUITS This block contains all circuits that provide the necessary supply voltages and bias currents for the internal circuitry.
PAGE 15
FUNCTIONAL DESCRIPTION FUNCTIONAL INTERNAL BLOCK DESCRIPTION TRACKING AND SEQUENCING This block allows the output of channel 2 of the 34716 to track 1/2 the voltage applied at the VREFIN pin. This allows the VREF and VTT voltages to track 1/2 VDDQ and assures that none of them will be higher than VDDQ at any point during normal operating conditions.
PAGE 16
FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES SD = 0 & STBY=x VTT<=VUVF2 VTT Under-voltage VDDQ=ON VTT=ON VREF=ON PG = 1 VTT=>=VUVR2 VTT>=VOVR2 VTT Over-voltage VDDQ=ON VTT=ON VREF=ON PG = 1 TJ >= 170°C Shutdown VDDQ = Discharge VTT = Discharge VREF = Discharge PG = 1 SD = 1 & STBY=1 Power Off VDDQ=OFF VTT=OFF VREF=OFF PG = 1 SD = 1 & STBY=1 3.0 V<=VIN<=6.
PAGE 17
FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES Soft start values are determined by reading the FREQ and ILIM1 pins respectively. A soft start cycle is then initiated to ramp up the outputs. While channel 1 buck converter uses an internal reference, channel 2 converter error amplifier uses the voltage on the VREFOUT pin (VREF) as its reference voltage. VREF is equal to 1/2 VDDQ, where VDDQ is applied to the VREFIN pin.
PAGE 18
TYPICAL APPLICATIONS TYPICAL APPLICATIONS 4 5 C27 0.1 F ILIM1 NC FREQ VIN VIN GND VDDI PGND2 PGND1 PGND2 VOUT1 6 7 8 9 10 PVIN2 16 SW2 16 SW2 PGND1 VOUT1 17 SW2 MC34716 SW1 SW2 0.1 F 17 15 GND 15 14 VOUT2 C11 0.1 F INV2 4 GND SW1 COMP2 3 PVIN2 SD SW1 PVIN2 PVIN1 C15 18 BOOT2 PVIN1 PG 3 BOOT2 21 20 19 BOOT1 VREFOUT 2 PVIN1 24 23 22 VREFIN 2 x ILIM1 COMP1 1 VIN FREQ INV1 C28 SW1 0.1 F STBY C14 0.
PAGE 19
TYPICAL APPLICATIONS I/O Signals GND GND PVIN1 VO1 3 2 1 PVIN2 VO2 3 2 1 3 2 1 VM VIN GND VIN Capacitors VIN J2 PGOOD LED VM VIN C17 10 F C16 0.1 F R7 1k J3 R8 10 k D1 LED VMASTER R9 10 k LED J4 ILIM1, FREQ Jumpers VO1 VMASTER STBY_nopop LED 1 2 2 1 VMASTER 1 3 5 7 9 J1 2 4 6 8 10 VREFIN VDDI R16 10 k PG STBY ILIM1 R22 10 k_nopop SD CON10A SD VDDI R12 10 k_nopop FREQ R11 10 k PVIN2 Capacitors PVIN1 Capacitors PVIN1 PVIN2 C1 0.
PAGE 20
TYPICAL APPLICATIONS CONFIGURING THE OUTPUT VOLTAGE: Channel 1 of the 34716 is a general purpose DC-DC converter, the resistor divider to the -INV1 node is responsible for setting the output voltage, according to the following equation: VOUT  R1   V REF   1  R2  Where VREF is the internal VBG=0.7 V. Channel 2 is a DDR specific voltage power supply, and the output voltage is given by the equation: VTT  680 0.936 - 1.092 733 0.781 - 0.936 787 0.625 - 0.780 840 0.469 - 0.624 893 0.
PAGE 21
TYPICAL APPLICATIONS SELECTING INDUCTOR Inductor Current Rise Time: Inductor calculation process is the same for both Channels. The equation is the following: dt _ I _ rise  (Vout  I out * ( Rds (on) _ ls  r _ w)) I out Vout Maximum Off Time Percentage  1 Vin _ max L  D'MAX T  D'MAX T Switching Period Rds (on) _ ls Drain – to – Source Resistance of FET r_w Winding Resistance of Inductor I OUT  0.
PAGE 22
TYPICAL APPLICATIONS 5. Equating pole 2 to 5 times the Crossover Frequency to achieve a faster response and a proper phase margin SWx Lx VOUTx RSx COx R1x CSx INVx CXx RFx 2  R F --------------------CF + Cx CX  Figure 12. Type III compensation network 1. Choose a value for R1 (R2only applies to Channel 1) 2. Consider a Crossover frequency of one tenth of the switching frequency, set the Zero pole frequency to Fcross/10 FP 0 1 1  FCROSS  10 2 * R1C F 1 CF  2 * R1 FPO 3.
PAGE 23
TYPICAL APPLICATIONS In order to effectively transfer heat from the top layer to the ground plane and other layers of the printed circuit board, thermal vias need to be used in the thermal pad design. It is VIN1 PVIN1 VIN2and and 23 Loop Curr ent HS ON HS Loop Curr ent HS ON HS SW1 SW2and and 2 3 SW1 SD recommended that 5 to 9 vias be spaced evenly and have a finished diameter of 0.3 mm.
PAGE 24
PACKAGING PACKAGING DIMENSIONS PACKAGING PACKAGING DIMENSIONS EP SUFFIX 26-PIN 98ASA10728D ISSUE 0 34716 24 Analog Integrated Circuit Device Data Freescale Semiconductor
PAGE 25
PACKAGING PACKAGING DIMENSIONS EP SUFFIX 26-PIN 98ASA10728D ISSUE 0 34716 Analog Integrated Circuit Device Data Freescale Semiconductor 25
PAGE 26
REVISION HISTORY REVISION HISTORY REVISION DATE DESCRIPTION OF CHANGES 1.0 2/2006 • 2.0 2/2007 • • 3.0 5/2007 • • • • Initial release Converted format from Market Assessment to Product Preview • Major updates to the data, form, and style • • • • • • • • • • • • • • • • • • • • 4.
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