|
|
PDF LT1766 Data sheet ( Hoja de datos )
| Número de pieza | LT1766 | |
| Descripción | 200kHz Step-Down Switching Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LT1766 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
|
No Preview Available !
LT1766/LT1766-5
5.5V to 60V 1.5A, 200kHz
Step-Down Switching Regulator
FEATURES
n Wide Input Range: 5.5V to 60V
n 1.5A Peak Switch Current
n Constant 200kHz Switching Frequency
n Saturating Switch Design: 0.2Ω
n Peak Switch Current Rating Maintained Over
Full Duty Cycle Range
n Low Effective Supply Current: 2.5mA
n Low Shutdown Current: 25μA
n 1.2V Feedback Reference Voltage (LT1766)
n 5V Fixed Output (LT1766-5)
n Easily Synchronizable
n Cycle-by-Cycle Current Limiting
n Small 16-Pin SSOP and Thermally Enhanced
TSSOP Packages
APPLICATIONS
n High Voltage, Industrial and Automotive
n Portable Computers
n Battery-Powered Systems
n Battery Chargers
n Distributed Power Systems
DESCRIPTION
The LT®1766/LT1766-5 are 200kHz monolithic buck switch-
ing regulators that accept input voltages up to 60V. A high
efficiency 1.5A, 0.2Ω switch is included on the die along
with all the necessary oscillator, control and logic circuitry.
A current mode control architecture delivers fast transient
response and excellent loop stability.
Special design techniques and a new high voltage process
achieve high efficiency over a wide input range. Efficiency
is maintained over a wide output current range by using the
output to bias the circuitry and by utilizing a supply boost
capacitor to saturate the power switch. Patented circuitry
maintains peak switch current over the full duty cycle range.
A shutdown pin reduces supply current to 25μA and the
device can be externally synchronized from 228kHz to
700kHz with logic-level inputs.
The LT1766/LT1766-5 are available in a 16-pin fused-lead
SSOP package or a TSSOP package with exposed backside
for improved thermal performance.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents, including 6498466, 6531909.
TYPICAL APPLICATION
VIN*
5.5V TO 60V
5V Buck Converter
6
4
2.2μF†
100V
CERAMIC
15
OFF ON
BOOST
VIN SW
LT1766
SHDN
BIAS
2
10
14
SYNC
12
FB
GND VC
1, 8, 9, 16 11
1N4148W
0.33μF
47μH
10MQ060N +
15.4k
4.99k
VOUT
5V
1A
100μF 10V
SOLID
TANTALUM
2.2k
0.022μF
220pF
1766 TA01
*FOR INPUT VOLTAGES BELOW 7.5V, SOME RESTRICTIONS MAY APPLY
†TDK C4532X7R2A225K
Efficiency vs Load Current
100
VOUT = 5V
L = 47μH
90
VIN = 12V
VIN = 42V
80
70
60
50
0
0.25 0.50 0.75 1.00
LOAD CURRENT (A)
1.25
1766 TA02
1766fc
1
1 page  
LT1766/LT1766-5
ELECTRICAL CHARACTERISTICS (LT1766H Grade)
The l denotes
VIN = 15V, VC =
specifications
1.5V, SHDN =
which apply over the full operating temperature
1V, BOOST open circuit, SW open circuit, unless
range, otherwise
otherwise noted.
specifications
are
at
TJ
=
25°C.
PARAMETER
CONDITIONS
MIN TYP MAX
fSW Line Regulation
fSW Frequency Shifting Threshold
Minimum Input Voltage
5.5V ≤ VIN ≤ 60V
Df = 10kHz
(Note 3)
l 0.05 0.15
0.8
l 4.6 5.5
Minimum Boost Voltage
Boost Current (Note 5)
Input Supply Current (IVIN)
Bias Supply Current (IBIAS)
Shutdown Supply Current
(Note 4) ISW ≤ 0.75A
l 1.8 3
Boost = VIN + 5V, ISW = 0.5A
Boost = VIN + 5V, ISW = 0.75A
l 12 40
l 45 100
(Note 6) VBIAS = 5V
1.4 2.2
(Note 6) VBIAS = 5V
2.9 4.2
SHDN = 0V, VIN ≤ 60V, SW = 0V, VC Open
25 120
l 500
Lockout Threshold
Shutdown Thresholds
Minimum SYNC Amplitude
VC Open
VC Open, Shutting Down
VC Open, Starting Up
l 2.3
2.42 2.68
l 0.15
l 0.25
0.37
0.45
0.9
0.9
l 1.5 2.2
SYNC Frequency Range
228 700
SYNC Input Resistance
20
UNITS
%/V
V
V
V
mA
mA
mA
mA
μA
μA
V
V
V
V
kHz
kΩ
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: Gain is measured with a VC swing equal to 200mV above the low
clamp level to 200mV below the upper clamp level.
Note 3: Minimum input voltage is not measured directly, but is guaranteed
by other tests. It is defined as the voltage where internal bias lines are still
regulated so that the reference voltage and oscillator remain constant.
Actual minimum input voltage to maintain a regulated output will depend
upon output voltage and load current. See Applications Information.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.
Note 5: Boost current is the current flowing into the BOOST pin with the
pin held 5V above input voltage. It flows only during switch on time.
Note 6: Input supply current is the quiescent current drawn by the input
pin when the BIAS pin is held at 5V with switching disabled. Bias supply
current is the current drawn by the BIAS pin when the BIAS pin is held
at 5V. Total input referred supply current is calculated by summing input
supply current (IVIN) with a fraction of bias supply current (IBIAS):
ITOTAL = IVIN + (IBIAS)(VOUT/VIN)
with VIN = 15V, VOUT = 5V, IVIN = 1.4mA, IBIAS = 2.9mA, ITOTAL = 2.4mA.
Note 7: Switch on-resistance is calculated by dividing VIN to SW voltage
by the forced current. See Typical Performance Characteristics for the
graph of switch voltage at other currents.
Note 8: The LT1766EGN, LT1766EGN-5, LT1766EFE and LT1766EFE-5
are guaranteed to meet performance specifications from 0°C to 125°C
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 LT1766IGN, LT1766IGN-5,
LT1766IFE and LT1766IFE-5 are guaranteed over the full –40°C to 125°C
operating junction temperature range. The LT1766HGN and LT1766HFE are
guaranteed over the full –40°C to 140°C operating junction temperature
range.
Note 9: Transconductance and voltage gain refer to the internal amplifier
exclusive of the voltage divider. To calculate gain and transconductance,
refer to the SENSE pin on fixed voltage parts. Divide the values shown by
the ratio VOUT/1.219.
Note 10: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 140°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 11: High junction temperatures degrade operating lifetimes.
Operating lifetime at junction temperatures between 125°C and 140°C is
derated to 1000 hours.
1766fc
5
5 Page 
APPLICATIONS INFORMATION
LT1766
Q2
TO FREQUENCY
SHIFTING
1.4V Q1
ERROR
AMPLIFIER
+
–
1.2V
R3
1k
R4
2k
BUFFER
TO SYNC CIRCUIT
LT1766/LT1766-5
VSW L1
OUTPUT
5V
R1
FB +
C1
R2
5k
VC GND
Figure 2. Frequency and Current Limit Foldback
1766 F02
divider impedance is not critical, caution should be used if
resistors are increased beyond the suggested values and
short-circuit conditions occur with high input voltage. High
frequency pickup will increase and the protection accorded
by frequency and current foldback will decrease.
40mV/DIV
VOUT AT IOUT = 1A
VOUT AT IOUT = 0.1A
CHOOSING THE INDUCTOR
For most applications, the output inductor will fall into
the range of 15μH to 100μH. Lower values are chosen to
reduce physical size of the inductor. Higher values allow
more output current because they reduce peak current
seen by the LT1766 switch, which has a 1.5A limit. Higher
values also reduce output ripple voltage.
When choosing an inductor you will need to consider
output ripple voltage, maximum load current, peak induc-
tor current and fault current in the inductor. In addition,
other factors such as core and copper losses, allowable
component height, EMI, saturation and cost should also
be considered. The following procedure is suggested
as a way of handling these somewhat complicated and
conflicting requirements.
Output Ripple Voltage
Figure 3 shows a typical output ripple voltage wave-
form for the LT1766. Ripple voltage is determined by
ripple current (ILP-P) through the inductor and the high
frequency impedance of the output capacitor. The fol-
lowing equations will help in choosing the required
0.5A/DIV
INDUCTOR CURRENT
AT IOUT = 1A
VIN = 40V
VOUT = 5V
L = 47μH
2.5μs/DIV
C = 100μF, 10V, 0.1Ω
INDUCTOR CURRENT
AT IOUT = 0.1A
1766 F03
Figure 3. LT1766 Ripple Voltage Waveform
inductor value to achieve a desirable output ripple volt-
age level. If output ripple voltage is of less importance,
the subsequent suggestions in Peak Inductor and Fault
Current and EMI will additionally help in the selection of
the inductor value.
Peak-to-peak output ripple voltage is the sum of a triwave
(created by peak-to-peak ripple current (ILP-P) times ESR)
and a square wave (created by parasitic inductance (ESL)
and ripple current slew rate). Capacitive reactance is as-
sumed to be small compared to ESR or ESL.
VRIPPLE
=
(ILP-P
)(ESR)
+
(ESL)
dI
dt
1766fc
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LT1766.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LT1761 | LDO Micropower Regulators | Linear Technology |
| LT1762 | LDO Micropower Regulators | Linear Technology |
| LT1763 | LDO Micropower Regulators | Linear Technology |
| LT1764 | LDO Regulators | 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 |