|
|
PDF LTC3856 Data sheet ( Hoja de datos )
| Número de pieza | LTC3856 | |
| Descripción | 2-Phase Synchronous Step-Down DC/DC Controller | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC3856 (archivo pdf) en la parte inferior de esta página. Total 40 Páginas | ||
|
No Preview Available !
Features
n PolyPhase® Controller Reduces Input and Output
Capacitance and Power Supply Induced Noise
n Wide VIN Range: 4.5V to 38V Operation
n ±0.75%, 0.6V Reference Voltage Accuracy
n High Efficiency: Up to 95%
n Programmable Burst Mode® Operation or
Stage Shedding™ for Highest Light Load Efficiency
n Active Voltage Positioning (AVP)
n RSENSE or DCR Current Sensing
n Programmable DCR Temperature Compensation
n Phase-Lockable Fixed Frequency: 250kHz to 770kHz
n True Remote Sense Differential Amplifier
n Dual N-Channel MOSFET Synchronous Drive
n VOUT Range: 0.6V to 5V without Differential Amplifier
n VOUT Range: 0.6V to 3.3V with Differential Amplifier
n Adjustable Soft-Start or VOUT Tracking
n Stackable for Up to 12-Phase Operation
n 32-Pin (5mm × 5mm) QFN and 38-Pin TSSOP Packages
Applications
n Telecom and Datacom Systems
n Industrial and Medical Instruments
n DC Power Distribution Systems
n Computer Systems
LTC3856www.DataSheet4U.com
2-Phase Synchronous
Step-Down DC/DC
Controller with Diffamp
Description
The LTC®3856 is a single output, dual channel PolyPhase
synchronous step-down DC/DC controller that drives all
N-channel power MOSFET stages. This device includes a
high speed differential amplifier for remote output volt-
age sense. Power loss and supply noise are minimized by
operating the two controller output stages out-of-phase
and up to 12-phase operation can be achieved.
The LTC3856 monitors the output current by sensing
the voltage drop across the output inductor (DCR) or by
using a sense resistor. DCR temperature compensation
maintains an accurate current sense threshold over a
broad temperature range. A constant-frequency, current
mode architecture allows a phase-lockable frequency of
up to 770kHz.
A wide 4.5V to 38V input supply range encompasses
most intermediate bus voltages and battery chemistries.
Burst Mode operation, continuous or Stage Shedding
modes are supported. A TK/SS pin shared by both chan-
nels ramps the output voltage during start-up.
L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase, Burst Mode and OPTI-LOOP
are registered trademarks and Stage Shedding is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6498466,
6580258, 6611131, 6674274.
Typical Application
High Efficiency 1.5V/50A Step-Down Converter
30.1k
S
20k
DIFFOUT VIN
TG1
VFB BOOST1
ILIM LTC3856 SW1
RUN BG1
PGOOD
CLKOUT
PHASMD
PLLIN
SENSE1+
SENSE1–
MODE
TG2
ITEMP
BOOST2
FREQ
SW2
122k
EXTVCC
DIFFN
DIFFP
BG2
INTVCC
SENSE2+
SENSE2–
ITH TK/SS GND AVP ISET
2200pF
1.5k 0.1µF
S
3856 TA01a
S
0.1µF
S
S
S
0.1µF
S
S
4.7µF
0.33µH
SS
0.33µH
SS
10µF
s 4
VIN
4.5V TO
20V
VOUT
1.5V
50A
100µF
s 8
Efficiency and Power Loss
vs Output Current
100
90
VIN = 12V
VOUT = 1.5V
80
70
Burst Mode
OPERATION
100
10
60
50 1
40
30
0
20
10
0
0.1 1
–1
10 100
LOAD CURRENT (A)
3856 TA01b
3856f
1 page  
LTC3856www.DataSheet4U.com
E lectrical Characteristics The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 15V, VRUN = 5V, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Differential Amplifier
ADA Gain
E-Grade
I-Grade
l 0.998
l 0.997
1 1.002
1 1.003
V/ V
V/ V
RIN
VOS
PSRR
ICL
VOUT(MAX)
Input Resistance
Input Offset Voltage
Power Supply Rejection Ratio
Maximum Output Current
Maximum Output Voltage
Measured at DIFFP Input
VDIFFP = VDIFFOUT = 1.5V, IDIFFOUT = 100µA
4.5V < VIN < 38V
IDIFFOUT = 300µA
80
100
23
VINTVCC VINTVCC
–1.4 –1.1
2
kΩ
mV
dB
mA
V
On-Chip Driver
TG RUP
TG RDOWN
BG RUP
BG RDOWN
GBW
TG Pull-Up RDS(ON)
TG Pull-Down RDS(ON)
BG Pull-Up RDS(ON)
BG Pull-Down RDS(ON)
Gain-Bandwidth Product
TG High
TG Low
BG High
BG Low
(Note 8)
2.6 Ω
1.5 Ω
2.4 Ω
1.1 Ω
3 MHz
SR Slew Rate
(Note 8)
2 V/µs
Stage Shedding Mode
IISET
Programmable Stage Shedding
Mode Current
6.5 7.5 8.5
µA
AVP (Active Voltage Positioning)
VAVP Maximum VOUT with AVP
ISINK Sink Current of AVP Pin
ISOURCE
Source Current of AVP Pin
VAVP-VO(MAX) Maximum Voltage Drop VAVP to VO
SENSE+ = 1.2V
SENSE+ = 1.2V
SENSE+ = 1.2V
2.5 V
250 µA
2 mA
120 mV
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3856 is tested under pulse load conditions such that
TJ ≈ TA. The LTC3856E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
The LTC3856I is guaranteed to meet performance specifications over the
full –40°C to 125°C operating junction temperature range.
Note 3: TJ is calculated from the ambient temperature, TA, and power
dissipation, PD, according to the following formula:
LTC3856UH: TJ = TA + (PD • 34°C/W)
LTC3856FE: TJ = TA + (PD • 25°C/W)
Note 4: The LTC3856 is tested in a feedback loop that servos VITH to a
specified voltage and measures the resultant VFB.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See the Applications Information
section.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7: The minimum on-time condition corresponds to the on inductor
peak-to-peak ripple current ≥40% of IMAX (see Minimum On-Time
Considerations in the Applications Information section).
Note 8: Guaranteed by design.
3856f
5 Page 
FUNCTIONAL Diagram
LTC3856www.DataSheet4U.com
MODE PLLIN PHASMD
FREQ
MODE/SYNC
DETECT
PLL-SYNC
ITEMP
TEMPSNS
0.6V
–+
F
EXTVCC
4.7V
–+
F
5V
REG
CLKOUT
ISET
ILIM
OSC
+
ICMP
–
3k
S
RQ
–
+ IREV
ISET ISET
FCNT
ON
BURSTEN
SWITCH
LOGIC
AND
ANTISHOOT-
THROUGH
RUN
OV
SLOPE
COMPENSATION
INTVCC
UVLO
1
51k
ITHB
SLOPE RECOVERY
ACTIVE CLAMP
SLEEP
VIN
0.6V
REF
0.55V
ISET
SS RUN
EA
0.5V 1.22V
+
UV
–
1.25µA
+
OV
–
3856 FD
ITH RC CC1
RUN TK/SS CSS
VIN
INTVCC
BOOST
TG
SW
SENSE+
SENSE–
BG
PGND
+
CIN
DB
CB
CVCC
VIN
INTVCC
M1
L1
M2
VOUT
+ COUT
PGOOD
0.54V
VFB
DIFFOUT
R2
+
DIFFAMP
–
RAVP
DIFFP
40k
40k
R1
0.66V
SGND
40k
RPRE-AVP
AVP
1µA
40k DIFFN
+–
SENSE1+
SENSE1–
+–
SENSE2+
SENSE2–
3856f
11
11 Page | ||
| Páginas | Total 40 Páginas | |
| PDF Descargar | [ Datasheet LTC3856.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC3850 | 2-Phase Synchronous Step-Down Switching Controller | Linear Technology |
| LTC3850-1 | 2-Phase Synchronous Step-Down Switching Controller | Linear Technology |
| LTC3850-2 | 2-Phase Synchronous Step-Down Switching Controller | Linear Technology |
| LTC3851 | Synchronous Step-Down Switching Regulator 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 |