Datasheet LTC3736-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual 2-Phase, No RSENSE , Synchronous Controller with Spread Spectrum |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTIO. Spread Spectrum Operation. Tracking Function. No … |
| File Format / Size | PDF / 541 Kb |
| Document Language | English |
FEATURES. DESCRIPTIO. Spread Spectrum Operation. Tracking Function. No Current Sense Resistors Required
Model Line for this Datasheet
Text Version of Document
LTC3736-1 Dual 2-Phase, No R TM SENSE , Synchronous Controller with Spread Spectrum
U FEATURES DESCRIPTIO
■
Spread Spectrum Operation
The LTC®3736-1 is a 2-phase dual synchronous step- ■
Tracking Function
down switching regulator controller with tracking that ■
No Current Sense Resistors Required
drives external complementary power MOSFETs using ■
Out-of-Phase Controllers Reduce Required
few external components. The constant frequency current
Input Capacitance
mode architecture with MOSFET VDS sensing eliminates ■
Wide VIN Range: 2.75V to 9.8V
the need for sense resistors and improves efficiency. ■ Current Mode Operation Power loss and noise due to the ESR of the input capaci- ■ 0.6V ±1.5% Voltage Reference tance are minimized by operating the two controllers out ■ Low Dropout Operation: 100% Duty Cycle of phase. ■ Pulse Skipping Operation at Light Loads A unique spread spectrum architecture randomly varies ■ Internal Soft-Start Circuitry the LTC3736-1’s switching frequency from 450kHz to ■ Power Good Output Voltage Monitor 580kHz, significantly reducing the peak radiated and con- ■ Output Overvoltage Protection ducted noise on both the input and output supplies, ■ Micropower Shutdown: IQ = 9µA making it easier to comply with electromagnetic interfer- ■ Tiny Low Profile (4mm × 4mm) QFN and Narrow ence (EMI) standards. SSOP Packages Pulse skipping operation provides high efficiency at light
U
loads. 100% duty cycle capability provides low dropout op-
APPLICATIO S
eration, extending operating time in battery-powered sys- ■ tems. The high switching frequencies allow for the use of One or Two Lithium-Ion Powered Devices ■ small surface mount inductors and capacitors. Notebook and Palmtop Computers, PDAs ■ Portable Instruments The LTC3736-1 is available in the low profile (0.75mm) ■ Distributed DC Power Systems 24-pin thermally enhanced (4mm × 4mm) QFN package , LTC and LT are registered trademarks of Linear Technology Corporation. and 24-lead narrow SSOP packages. No RSENSE is a trademark of Linear Technology Corporation. Protected by U.S. Patents including 5481178, 5929620, 6144194, 6580258, 6304066, 6611131, 6498466.
U TYPICAL APPLICATIO Output Voltage Frequency Low Noise, 2-Phase, Dual Synchronous DC/DC Step-Down Converter Spectrum
VIN –10 2.75V TO 9.8V FIGURE 13 CIRCUIT SPREAD SPECTRUM –20 V V 10µF OUT = 2.5V DISABLED IN ×2 R –30 BW = 30Hz SENSE1+ SENSE2+ SPREAD SPECTRUM –40 TG1 TG2 ENABLED 2.2 –50 µH SW1 SW2 2.2µH LTC3736-1 –60 BG1 BG2 –70 PGND PGND AMPLITUDE (dBm) –80 187k 118k VOUT1 V V OUT2 FB1 VFB2 –90 2.5V 1.8V + ITH1 ITH2 + –100 220pF SGND 220pF 47µF 47µF –110 410k 450k 490k 530k 570k 610k 59k 15k 15k 59k FREQUENCY (Hz) 37361 TA01b 37361 TA01a 37361f 1
U FEATURES DESCRIPTIO
■
Spread Spectrum Operation
The LTC®3736-1 is a 2-phase dual synchronous step- ■
Tracking Function
down switching regulator controller with tracking that ■
No Current Sense Resistors Required
drives external complementary power MOSFETs using ■
Out-of-Phase Controllers Reduce Required
few external components. The constant frequency current
Input Capacitance
mode architecture with MOSFET VDS sensing eliminates ■
Wide VIN Range: 2.75V to 9.8V
the need for sense resistors and improves efficiency. ■ Current Mode Operation Power loss and noise due to the ESR of the input capaci- ■ 0.6V ±1.5% Voltage Reference tance are minimized by operating the two controllers out ■ Low Dropout Operation: 100% Duty Cycle of phase. ■ Pulse Skipping Operation at Light Loads A unique spread spectrum architecture randomly varies ■ Internal Soft-Start Circuitry the LTC3736-1’s switching frequency from 450kHz to ■ Power Good Output Voltage Monitor 580kHz, significantly reducing the peak radiated and con- ■ Output Overvoltage Protection ducted noise on both the input and output supplies, ■ Micropower Shutdown: IQ = 9µA making it easier to comply with electromagnetic interfer- ■ Tiny Low Profile (4mm × 4mm) QFN and Narrow ence (EMI) standards. SSOP Packages Pulse skipping operation provides high efficiency at light
U
loads. 100% duty cycle capability provides low dropout op-
APPLICATIO S
eration, extending operating time in battery-powered sys- ■ tems. The high switching frequencies allow for the use of One or Two Lithium-Ion Powered Devices ■ small surface mount inductors and capacitors. Notebook and Palmtop Computers, PDAs ■ Portable Instruments The LTC3736-1 is available in the low profile (0.75mm) ■ Distributed DC Power Systems 24-pin thermally enhanced (4mm × 4mm) QFN package , LTC and LT are registered trademarks of Linear Technology Corporation. and 24-lead narrow SSOP packages. No RSENSE is a trademark of Linear Technology Corporation. Protected by U.S. Patents including 5481178, 5929620, 6144194, 6580258, 6304066, 6611131, 6498466.
U TYPICAL APPLICATIO Output Voltage Frequency Low Noise, 2-Phase, Dual Synchronous DC/DC Step-Down Converter Spectrum
VIN –10 2.75V TO 9.8V FIGURE 13 CIRCUIT SPREAD SPECTRUM –20 V V 10µF OUT = 2.5V DISABLED IN ×2 R –30 BW = 30Hz SENSE1+ SENSE2+ SPREAD SPECTRUM –40 TG1 TG2 ENABLED 2.2 –50 µH SW1 SW2 2.2µH LTC3736-1 –60 BG1 BG2 –70 PGND PGND AMPLITUDE (dBm) –80 187k 118k VOUT1 V V OUT2 FB1 VFB2 –90 2.5V 1.8V + ITH1 ITH2 + –100 220pF SGND 220pF 47µF 47µF –110 410k 450k 490k 530k 570k 610k 59k 15k 15k 59k FREQUENCY (Hz) 37361 TA01b 37361 TA01a 37361f 1
