|
|
PDF LTC3860 Data sheet ( Hoja de datos )
| Número de pieza | LTC3860 | |
| Descripción | Voltage Mode DC/DC Controller | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC3860 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
|
No Preview Available !
LTC3860www.DataSheet4U.com
Features
Dual, Multiphase Step-Down
Voltage Mode DC/DC Controller
with Current Sharing
Description
n Constant Frequency Voltage Mode Control with
Accurate Current Sharing
n ±0.75% 0.6V Voltage Reference
n Differential Remote Output Voltage Sense Amplifier
n Multiphase Capability—Up to 12-Phase Operation
n Programmable Current Limit
n Safely Powers a Pre-Biased Load
n Programmable or PLL-Synchronizable Switching
Frequency Up to 1.25MHz
n Lossless Current Sensing Using Inductor DCR or
Precision Current Sensing with Sense Resistor
n Fast and Accurate True Operational Error Amplifiers
n VCC Range: 3V to 5.5V
n VIN Range: 3V to 24V
n Power Good Output Voltage Monitor
n Output Voltage Tracking Capability
n Programmable Soft-Start
n Available in a 32- Pin 5mm × 5mm QFN Package
Applications
n High Current Distributed Power Systems
n Digital Signal Processor and ASIC Supplies
n Telecom Systems
n Industrial Power Supplies
The LTC®3860 is a dual, PolyPhase® synchronous step-
down switching regulator controller for high current
distributed power systems, digital signal processors, and
other telecom and industrial DC/DC power supplies. It uses
a constant frequency voltage mode architecture combined
with very low offset, high bandwidth error amplifiers and
a remote output sense differential amplifier for excellent
transient response and output regulation.
The controller incorporates lossless inductor DCR current
sensing to maintain current balance between phases and to
provide overcurrent protection. The chip operates from a
VCC supply between 3V and 5.5V and is designed for step-
down conversion from VIN between 3V and 24V to output
voltages between 0.6V and VCC – 0.5V.
The TRACK/SS pins provide programmable soft-start or
tracking functions. Inductor current reversal is disabled
during soft-start to safely power prebiased loads. The con-
stant operating frequency can be synchronized to an exter-
nal clock or linearly programmed from 250kHz to 1.25MHz.
Up to six LTC3860 controllers can operate in parallel for
1-, 2-, 3-, 4-, 6- or 12-phase operation.
The LTC3860 is available in a 32-pin 5mm × 5mm QFN
package.
L, LT, LTC, LTM, PolyPhase, µModule, Linear Technology and the Linear logo are registered
trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
6144194, 5055767
Typical Application
VIN
VOUT
VCC
1nF
20k 220Ω 33pF
20k 220pF 12.7k
470µF
1µF
0.1µF
PWM1
VINSNS
VCC
FREQ
FB2
RUN1,2
ILIM1
ISNS1P
ILIM2
FB1
ISNS1N
LTC3860 ISNS2N
COMP1,2
ISNS2P
SS1,2
VSNSOUT
VSNSN
VSNSP
SGND
PWM2
IAVG
CLKIN
PWM1
VCC
50k
LTC4449
IN GND
VLOGIC
VCC
BOOST
TG
TS
BG
0.22µF
0.22µF
0.22µF
PWM2
VCC
100pF
LTC4449
IN GND
VLOGIC
VCC
BOOST
TG
TS
BG
0.22µF
VIN
TG1
SW1
0.3µH
BG1
2.32k
VIN 2.32k
TG2
SW2
0.3µH
BG2
VOUT
1.2V
330µF 50A
s4
3860 TA01
3860f
1 page  
Typical Performance Characteristics
LTC3860www.DataSheet4U.com
Load Step Transient Response
(2-Phase with 50% Inductor
Mismatch)
VOUT(AC)
100mV/DIV
ILOAD
20A/DIV
IL1 = 320nH
10A/DIV
IL2 = 220nH
10A/DIV
VIN = 12V
50µs/DIV
VOUT = 1.2V
ILOAD = 0A TO 25A
3860 G05
Efficiency and Power Loss
vs Load Current
100
90
VIN = 6V
VOUT = 1.2V
80
70
7
6
5
60 4
50
40 3
30 2
20
10 1
0
0.001
0.01 0.1
1
10
LOAD CURRENT (A)
0
100
3860 G06
Efficiency and Power Loss
vs Supply Voltage
90 6.0
88
VOUT = 1.2V
IOUT = 15A
5.5
86 5.0
84 4.5
82 4.0
80 3.5
78 3.0
76 2.5
74 2.0
72 1.5
70 1.0
6 7 8 9 10 11 12 13 14
SUPPLY VOLTAGE (V)
3860 G07
Short-Circuit Protection
SW NODE
5V/DIV
VOUT
1V/DIV
VIN = 12V
10ms/DIV
VOUT = 1.2V
ILOAD = SHORTED
3860 G08
Regulated VFB vs Supply Voltage
0.604
0.602
0.600
0.598
0.596
3
45
SUPPLY VOLTAGE (V)
6
3860 G10
Oscillator Frequency vs RFREQ
1.7
1.5
1.3
1.1
0.9
0.7
0.5
0.3
0.1
0
20 40 60 80 100 120
RFREQ (kΩ)
3860 G11
Oscillator Frequency
vs Temperature
610
605
600
595
590
585
580
575
–50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
3860 G12
3860f
5 Page 
Operation (Refer to Functional Diagram)
Overcurrent Protection
The current sense amplifier outputs also connect to
overcurrent (OC) comparators that provide fault protec-
tion in the case of an output short. When an OC fault is
detected, the controller three-states the PWM output,
resets the soft-start capacitor, and waits for 32768 clock
cycles before attempting to start up again. The LTC3860
also provides negative OC (NOC) protection by preventing
turn-on of the bottom MOSFET during a negative OC fault
condition. The negative OC threshold is equal to –3/4 the
positive OC threshold. See Applications Information for
guidelines on setting these thresholds.
Excellent Transient Response
The LTC3860 error amplifiers are true operational ampli-
fiers, meaning that they have high bandwidth, high DC gain,
low offset and low output impedance. Their bandwidth,
when combined with high switching frequencies and low-
value inductors, allows the compensation network to be
optimized for very high control loop crossover frequencies
and excellent transient response. The 600mV internal ref-
erence allows regulated output voltages as low as 600mV
without external level-shifting amplifiers.
Line Feedforward Compensation
The LTC3860 achieves outstanding line transient response
using a feedforward correction scheme which instanta-
neously adjusts the duty cycle to compensate for changes
in input voltage, significantly reducing output overshoot
LTC3860www.DataSheet4U.com
and undershoot. It has the added advantage of making
the DC loop gain independent of input voltage. Figure 2
shows how large transient steps at the input have little
effect on the output voltage.
VOUT
50mV/DIV
IL
2A/DIV
VIN
5V/DIV
COMP1
100mV/DIV
20µs/DIV
VOUT = 1.2V
VIN STEP = 7V TO 14V
Figure 2
3860 G20
Remote Sense Differential Amplifier
The LTC3860 includes a low offset, unity gain, high
bandwidth differential amplifier for remote output sens-
ing. Output voltage accuracy is significantly improved
by removing board interconnection losses from the total
error budget.
The LTC3860 differential amplifier has a typical output
slew rate of 45V/µs, bandwidth of 20MHz, input referred
offset < 2mV and a typical maximum output voltage of VCC
– 1V. The amplifier is configured for unity gain, meaning
that the differential voltage between VSNSP and VSNSN is
translated to VSNSOUT, relative to SGND.
3860f
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTC3860.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC3860 | Voltage Mode DC/DC Controller | Linear Technology |
| LTC3861 | Multiphase Step-Down Voltage Mode DC/DC Controller | Linear Technology |
| LTC3861-1 | Multiphase Step-Down Voltage Mode DC/DC Controller | Linear Technology |
| LTC3862 | Multi-Phase Current Mode Step-Up DC/DC Controller | Linear Technology |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |