DC2383A-B Evaluation Board
Quad 17V, 1.25A Synchronous Step-DownRegulator with Ultralow Quiescent Current
Demonstration circuit 2383A-B features the LT ® 3644-2: the wide input and output voltage range, high efficiency and power density, quad 1.25A outputs DC/DC synchronous step-down monolithic regulator. The input voltage range of DC2383A-A is 2.7V to 17V. The default demo board setting of VOUT1, VOUT2, VOUT3, and VOUT4 is 1.2V, 3.3V, 2.5V, and 1.8V at 1.25A maximum DC output current per channel. There are two assembly versions. The DC2383A-B features LTC3644-2 which operates at an internally fixed frequency of 2.25MHz (Typ), while the DC2383A-A features LTC3644 which operates at an internally fixed frequency of 1MHz (Typ). Peak current limit is internally fixed at 2.2A typical per channel. Each channel comes with independent run pin control and power good indicators. Phase shift selection of either 0 degrees or 180 degrees between switch rising edge of channels 1, 2 and channels 3, 4 is also available.
DC2383A-B provides optional onboard 0Ω jumpers to configure the LTC3644-2 as 4-phase dual 2.5A/2.5A outputs or 4-phase triple 2.5A/1.25A/1.25A outputs. Optional 0Ω jumpers connecting VIN1 to VIN2, VIN3, and
VIN4 are available for users to operate selected channels of LTC3644-2 at different input voltages than VIN1.
A user-selectable MODE/SYNC input is provided to allow users to trade off ripple noise for light load efficiency: pulse-skipping mode (PS) or Burst Mode ® operation delivers higher efficiency at light load while forced continuous conduction mode (FCM) is preferred for noise sensitive applications. The MODE/SYNC pin can also be used to synchronize the switching frequency to an external clock or set the phase shift between channels 1, 2, and channels 3, 4. Constant frequency, peak current mode control architecture and integrated internal control loop compensation network, allows very fast transient response to line and load changes while maintaining loop stability.
The LTC3644-2 is available in a thermally enhanced, low-profile 36-lead 5mm x 5mm BGA package. It is recommended to read the LTC3644-2 datasheet and demo board manual prior to using or making any changes to DC2383A-B.
Specifications are at TA = 25°
|Input Voltage Range VIN||2.7||17||V|
|Demo Board Default Output Voltages VOUT1, VOUT2, VOUT3, VOUT4||FSW = 2.25
VIN = 2.7V to 17V (VOUT < VIN)
ILOAD = 0A to 1.25A per Channel
|1.176 3.234 2.45 1.764||1.2 3.3
|Default Switching Frequency||Internally Fixed Switching Frequency||1.8||2.25||2.6||MHz|
|Maximum Continuous Output Current IOUT per Channel IOUT1, IOUT2, IOUT3, IOUT4||FSW = 2.25MHz VIN = 2.7V to 17V (VOUT < VIN) VOUT = 1.2V, 1.8V, 2.5V, 3.3V||1.25||A|
|Efficiency at DC||VIN = 5V FSW = 2.25MHz||125||%|
|VOUT1 = 1.2V at IOUT1 = 1A||80.6|
|VOUT2 = 3.3V at IOUT2 = 1A||88.1|
|VOUT3 = 2.5V at IOUT3 = 1A||86.2|
|VOUT4 = 1.8V at IOUT4 = 1A||84.7|
QUICK START PROCEDURE
The MODE/SYNC pin can be used to synchronize the internal oscillator clock frequency to the external clock signal. Place JP3 (MODE/PLLIN) at the CLKIN position, apply an external clock signal at the CLKIN test point (E10) to vary the switching frequency within ±50% of the internal programmed frequency.
The MODE/SYNC pin can also be used to set the phase shift between channels 1, 2 and channels 3, 4 while keeping the PHASE pin tied to INTVCC. The phase shift can be set by modulating the duty cycle of an external clock on the MODE/SYNC pin. In this case, the phase shift will be determined by the applied external clock rising and falling edges. The switch rising edge of channels 1, 2 is synced to the rising edge of the external clock and the switch rising edge of channels 3, 4 is synced to the falling edge of the external clock. Crosstalk between channels can be avoided by adjusting the phase shift between channels such that the SW edges do not coincide.
(Option) 4-Phase Dual 2.5A/2.5A Output Current Configuration:
DC2383A-B can be configured as dual 2.5A/2.5A outputs.
Channel 1 and channel 4 are master channels, and channel 2 and channel 3 are slaves.
The following simple modification is required:
- Tie VIN1, VIN2, VIN3, and VIN4 together or tie VIN1 and VIN2, VIN3 and VIN4 together if operating channels 1 and channel 2 at different input voltage than that of channel 3 and channel 4. Make sure SVIN is tied to the highest input supply voltage.
- Tie SW1 and SW2, SW3 and SW4 together. Since SW1 and SW2, SW3 and SW4 are tied together, there is only one inductor needed for each output voltage rail. Calculate and insert the inductors needed for L1 and L4, and remove L2 and L3.
- Tie FB2 and FB3 to INTVCC.
- Float (do not use) PGOOD2 and PGOOD3. Only PGOOD1 and PGOOD4 are active.
- Tie RUN1 and RUN2, RUN3 and RUN4 together. Note: Make sure to float all the unused onboard RUN pin jumpers to avoid accidentally shorting VIN to GND.
- Tie PHASE pin to INTVCC. Refer to the demo board DC2383A-B schematic for more details.
(Option) 4-Phase Triple 2.5A/1.25A/1.25A Output Circuit Configuration:
DC2383A-B can be configured as triple 2.5A/1.25A/1.25A outputs.
Channel 1 is a master channel, channel 2 is a slave. Channel 3 and channel 4 are independent channels.
The following simple modification is required:
- Tie VIN1, VIN2, VIN3, and VIN4 together, or tie VIN1 and VIN2 together, and VIN3 and VIN4 can be at different input voltages than VIN1 and VIN2. Make sure SVIN is tied to the highest input supply voltage.
- Tie SW1 and SW2 together. There is only one inductor needed for this output voltage rail. Calculate and insert the inductor needed for L1 and remove L2.
- Tie FB2 to INTVCC.
- Float (do not use) PGOOD2. Only PGOOD1, PGOOD3, and PGOOD4 are active.
- Tie RUN1 and RUN2 together. Note: Make sure to float all unused onboard RUN pin jumpers to avoid accidentally shorting VING to GND.
- Tie PHASE pin to INTVCC.
- Channel 3 and Channel 4 are left unchanged since these two channels operate as independent channels.
Refer to the demo board DC2383A-B schematic for more details.
QUICK START PROCEDURE
QUICK START PROCEDURE
Figure 3. Measured Efficiency at VIN = 5V, FSW = 2.25MHz, Burst Mode
VOUT1 = 1.2V, VOUT2 = 3.3V, VOUT3 = 2.5V, VOUT4 = 1.8V
ILOAD = 1.25A per Channel
TA = 25°C, No Heat Sink, No Forced Airflow
Figure 4. Thermal Performance at VIN = 5V, fSW = 2.25MHz
|(a) Load Transient Response: VIN = 8V, VOUT = 1.2V||(b) Load Transient Response: VIN = 12V, VOUT = 1.8V|
|(c) Load Transient Response: VIN = 12V, VOUT = 2.5V||(d) Load Transient Response: VIN = 12V, VOUT = 3.3V|
Figure 5. Load Transient Responses
Load Transient Response Test Conditions:
FSW = 2.25MHz Typical
VOUT1 = 1.2V, VOUT2 = 3.3V, VOUT3 = 2.5V, VOUT4 = 1.8V
L1 = L4 = 1µH
L2 = L3 = 2.2µH
Load Step = 0.625A to 1.25A at di/dt = 1A/µs
COUT_ceramic = 1×47µF/1206 + 1x10uF/1206 (per Channel)
Feedforward Capacitor: CFF = 68pF (per Channel)
|ITEM||QTY||REFERENCE||PART DESCRIPTION||MANUFACTURER/PART NUMBER|
Required Circuit Components
|1||4||CFF1, CFF2, CFF3, CFF4||CAP, 0402 68pF 5% 50V C0G||MURATA, GRM1555C1H680JA01D|
|2||1||C1||CAP. 2917 22uF 20% 35V TANT||AVX, TPSE226M035R0125|
|3||7||C2, C4, C5, C7, C9, C10, C14||CAP, 0805 10uF 10% 25V X5R||MURATA, GRM21BR61E106KA73L|
|4||5||C3, C6, C11, C12, C15||CAP, 0603 4.7uF 20% 25V X5R||MURATA, GRM188R61E475ME11D|
|5||1||C16||CAP, 0603 1uF 10% 25V X7R||MURATA, GRM188R71E105KA12D|
|6||4||C19, C21, C23, C25||CAP, 1206 47uF 10% 16V X5R||MURATA, GRM31CR61C476ME44L|
|7||4||C20, C22, C24, C26||CAP, 1206 10uF 10% 25V X7R||KEMET, C1206C106K3RACTU|
|8||2||L1, L4||IND, 1uH||MURATA, DFE252012F-1R0M|
|9||2||L2, L3||IND, 2.2uH||MURATA, DFE252012F-2R2M|
|10||5||RSET1, RSET2, RSET3, RSET4, R25||RES, 0402 100K OHM 1% 1/16W||PANASONIC, ERJ2RKF1003X|
|11||9||R1, R2, R9, R13, R14, R17, R18, R23, R24||RES, 0402 0 OHM JUMPER||VISHAY, CRCW04020000Z0ED|
|12||4||R3, R4, R5, R6||RES, 0402 100k OHMS 1% 1/16W||VISHAY, CRCW0402100KFKED|
|13||1||R7||RES, 0402 2.2 OHMS 1% 1/16W||VISHAY, CRCW04022R20FNED|
|14||6||R8, R10, R11, R12, R15, R16||RES, 0402 10M OHMS 1% 1/16W||VISHAY, CRCW040210M0FKED|
|15||1||R19||RES, 0402 22.1K OHMS 1% 1/16W||VISHAY, CRCW040222K1FKED|
|16||1||R22||RES, 0402 31.6K OHM 1% 1/16W||VISHAY, CRCW040231K6FKED|
|17||1||R28||RES, 0402 49.9K OHMS 1% 1/16W||VISHAY, CRCW040249K9FKED|
|18||3||R29, R30, R31||RES, 0805 0 OHM JUMPER||VISHAY, CRCW08050000Z0EA|
|19||1||U1||IC, QUAD 17V, 1.25A SYNCHRONOUS STEP-DOWN REGULATOR||ANALOG DEVICES, LTC3644EY-2|
Additional Demo Board Circuit Components
|1||0||C8, C13, C17, C18||CAP, 0402 OPTION||OPTION|
|2||0||C27, C28, C29, C30||CAP, 1206 OPTION||OPTION|
|3||0||R20, R21, R26, R27||RES, 0402 OPTION||OPTION|
|4||0||R32||RES, 1206 OPTION||OPTION|
|5||0||R33, R34, R37, R38, R39||RES, 0603 OPTION||OPTION|
|6||0||R35, R36||RES, 0805 OPTION||OPTION|
Hardware: For Demo Board Only
|1||16||E1, E2, E3, E4, E5, E6, E7, E12, E14, E15, E16, E17, E18, E19, E20, E21||TURRET||MILL-MAX, 2501-2-00-80-00-00-07-0|
|2||10||E8, E9, E10, E11, E13, E22, E23, E24, E25, E26||TURRET||MILL-MAX, 2308-2-00-80-00-00-07-0|
|3||5||JP1, JP2, JP4, JP5, JP6||HEADER, 3PIN, 2mm||WURTH, ELEKTRONIK, 62000311121|
|4||1||JP3||HEADER, 2X4PINS 2mm||WURTH, ELEKTRONIK, 62000821121|
|5||4||JP7, JP8, JP9, JP10||HEADER, 2PIN, DBL ROW 2mm||WURTH, ELEKTRONIK, 62000421121|
|6||4||MH1, MH2, MH3, MH4||STANDOFF, SNAP ON 12.7mm||WURTH, ELEKTRONIK, 702935000|
|7||10||XJP1, XJP2, XJP3, XJP4, XJP5, XJP6, XJP7, XJP8, XJP9, XJP10||SHUNT, 2mm||WURTH, ELEKTRONIK, 60800213421|
OPTIONAL JUMPERS FOR PARALLELING PHASES FOR DESIRED NUMBER OF OUTPUT VOLTAGE RAILS (SHARING THE SAME VIN1)
|NUMBER OF OUTPUT VOLTAGE RAILS||Paralleling Channel||Master Channel||0 OHM (Required)||OPT (Do not stuff)||PHASE (JP13)|
|QUAD 1.25A 4||1/2/3/4||R33, R34, R35, R36, R37, R38, R39||INTVCC|
|TRIPLE 2.5A/1.25A/1.25A 3||1+2/3/4||1||R33, R35, R37||R4, R9, R10, R17, RSET2, CFF2, R19, R34, R36, R38, R39, L2, JP2||INTVCC|
|DUAL 2.5A/2.5A 2||1+2/3+4||1, 4||R33, R34, R35, R36, R37, R38||R4, R5, R9, R10, R13, R15, R17, R18, RSET2, RSET3, CFF2, CFF3, R19, R22, R39 L2, L3, JP2, JP5||INTVCC|
Please refer to the datasheet and demo board manual for more details and examples of paralleling phases to obtain the desired number of output voltage rails.
ANALOG DEVISES INC. HAS MADE THE BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER’S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT NALOG DEVICES INC. APPLICATIONS ENGINEERING FOR ASSISTANCE.
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Documents / Resources
|ANALOG DEVICES DC2383A-B Evaluation Board [pdf] User Guide|
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