LT1076IT-5 [Linear]
5V Step-Down Switching Regulator; 5V降压型开关稳压器型号: | LT1076IT-5 |
厂家: | Linear |
描述: | 5V Step-Down Switching Regulator |
文件: | 总4页 (文件大小:173K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1076-5
5V Step-Down
Switching Regulator
U
DESCRIPTIO
EATURE
Fixed 5V Output
2A On-Board Switch
100kHz Switching Frequency
2% Output Voltage Tolerance Over Temperature
Greatly Improved Dynamic Behavior
Available in Low Cost 5-Lead Package
Only 9.5mA Quiescent Current
Operates Up to 60V Input
S
F
■
■
■
■
■
■
■
■
The LT1076-5 is a 2A fixed 5V output monolithic bipolar
switching regulator which requires only a few external
partsfornormaloperation.Thepowerswitch,alloscillator
and control circuitry, all current limit components, and an
output monitor are included on the chip. The topology is
a classic positive “buck” configuration but several design
innovations allow this device to be used as a positive-to-
negative converter, a negative boost converter, and as a
flyback converter. The switch output is specified to swing
40V below ground, allowing the LT1076-5 to drive a
tapped inductor in the buck mode with output currents up
to 4A.
O U
PPLICATI
A
S
■
5V Output Buck Converter
Tapped Inductor Buck Converter with 4A Output
at 5V
TheLT1076-5usesatrueanalogmultiplierinthefeedback
loop. This makes the device respond nearly instanta-
neously to input voltage fluctuations and makes loop gain
independent of input voltage. As a result, dynamic behav-
ior of the regulator is significantly improved over previous
designs.
■
■
Positive-to-Negative Converter
On-chippulsebypulsecurrentlimitingmakestheLT1076-
5 nearly bust-proof for output overloads or shorts. The
input voltage range as a buck converter is 8V to 60V, but
aself-bootfeatureallowsinputvoltagesaslowas5Vinthe
inverting and boost configurations.
The LT1076-5 is available in a low cost 5-lead TO-220
package with frequency pre-set at 100kHz and current
limit at 2.6A. See Application Note 44 for design details.
U
O
TYPICAL APPLICATI
Basic Positive Buck Converter
100µH**†
5V
V
V
8V TO 40V
IN
SW
≤1.8A
LT1076-5
MBR340*
MBR330P MAY BE USED
*
FOR V ≤ 25V
IN
SENSE
COILTRONICS #100-1-52
HURRICANE #HL-AG210LL
**
V
C
GND
R3
†
VALUE MAY BE REDUCED TO 50µH
1.5k
FOR OUTPUT LOADS BELOW 1.5A
+
+
C3
200µF
C2
0.033µF
C1
500µF
LT1076-5 TA01
25V
1
LT1076-5
W W W
U
/O
ABSOLUTE AXI U RATI GS
PACKAGE RDER I FOR ATIO
Input Voltage
FRONT VIEW
ORDER PART
7
6
5
4
3
2
1
SHDN
LT1076-5............................................................ 45V
LT1076HV-5 ....................................................... 64V
Switch Voltage with Respect to Input Voltage
LT1076-5............................................................ 64V
LT1076HV-5 ....................................................... 75V
Switch Voltage with Respect to Ground Pin
V
C
NUMBER
SENSE
GND
I
LIM
SW
IN
V
V
LT1076CR-5
R PACKAGE
7-LEAD PLASTIC DD
TJMAX = 110°C
θ WILLVARYFROMAPPROXIMATELY30°C/WWITH
2.8IN2 OF 1 OZ COPPER TO 70°C/W WITH 0.20IN2 OF
1 OZ COPPER.
(VSW Negative)
LT1076-5 (Note 5).............................................. 35V
LT1076HV-5 (Note 5) ......................................... 45V
Sense Pin Voltage........................................... –2V, 10V
Maximum Operating Ambient Temperature Range
LT1076C-5, LT1076HVC-5 ..................... 0°C to 70°C
LT1076I-5, LT1076HVI-5 .................. –40°C to 85°C
Maximum Operating Junction Temperature Range
LT1076C-5, LT1076HVC-5 ................... 0°C to 125°C
LT1076I-5, LT1076HVI-5 ................ –40°C to 125°C
Maximum Storage Temperature .......... –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
FRONT VIEW
LT1076CT-5
LT1076HVCT-5
LT1076IT-5
5
4
3
2
1
V
IN
V
V
SW
C
GND
SENSE
LT1076HVIT-5
T PACKAGE
5-LEAD TO-220
FOR STRAIGHT LEADS, ORDER FLOW 06
JMAX = 110°C, θJA = 130°C/W
T
FRONT VIEW
SHDN
V
7
6
5
4
3
2
1
C
SENSE
LT1076CY-5
GND
I
LIM
V
SW
V
IN
Y PACKAGE
7-LEAD TO-220
T
JMAX = 110°C, θJA = 130°C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
TJ = 25°C, VIN = 25V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Switch “On” Voltage (Note 1)
I
I
= 0.5A
= 2A
●
●
1.2
1.7
V
V
SW
SW
Switch “Off” Leakage
V
IN
V
IN
= 25V, V = 0
150
250
µA
µA
SW
= V
, V = 0 (Note 6)
MAX SW
Supply Current (Note 2)
V
= 5.5V, V ≤ 40V
IN
= 0.1V (Device Shutdown) (Note 8)
●
●
8.5
9.0
140
11
12
300
mA
mA
µA
OUT
IN
40V < V < 60V
V
SHDN
Minimum Supply Voltage
Normal Mode
Start-Up Mode (Note 3)
●
●
7.3
3.5
8.0
4.8
V
V
Switch Current Limit (Note 4)
I
= Open
LIM
LIM
●
2
2.6
1.8
1.2
3.2
A
A
A
LIM
R
R
= 10k (Note 9)
= 7k (Note 9)
Maximum Duty Cycle
●
85
90
%
2
LT1076-5
ELECTRICAL CHARACTERISTICS TJ = 25°C, VIN = 25V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Switching Frequency
90
85
100
110
120
kHz
kHz
kHz
T ≤ 125°C
OUT
●
●
J
V
= V
= 0V (Note 4)
SENSE
20
Switching Frequency Line Regulation
Error Amplifier Voltage Gain (Note 7)
Error Amplifier Transconductance (Note 7)
Error Amplifier Source and Sink Current
8V ≤ V ≤ V
(Note 7)
0.03
2000
5000
0.1
%/ V
V/ V
IN
MAX
1V ≤ V ≤ 4V
C
3700
8000
µmho
Source (V
= 4.5V)
= 5.5V)
100
0.7
140
1.0
225
1.6
µA
mA
SENSE
Sink (V
SENSE
Sense Pin Divider Resistance
Sense Voltage
3
5
5
8
kΩ
V = 2V
●
●
●
●
4.85
5.15
V
C
Output Voltage Tolerance
V
OUT
(Nominal) = 5V
±0.5
±1.0
±2
±3
%
%
All Conditions of Input Voltage, Output Voltage,
Temperature and Load Current
Output Voltage Line Regulation
8V ≤ V ≤ V
(Note 6)
MAX
0.005
0.02
%/ V
IN
V Voltage at 0% Duty Cycle
C
1.5
–4.0
V
Over Temperature
mV/°C
Multiplier Reference Voltage
Shutdown Pin Current
24
10
V
V
SHDN
V
SHDN
= 5V
5
20
50
µA
µA
≤ V
( 2.5V)
THRESHOLD
Shutdown Thresholds
Switch Duty Cycle = 0
Fully Shut Down
2.2
0.1
2.45
0.30
2.7
0.5
V
V
Thermal Resistance Junction to Case
4
°C/W
The
●
denotes specifications which apply over the full operating
Note 5: Switch to input voltage limitation must also be observed.
Note 6: V = 40V for the LT1076-5 and 60V for the LT1076HV-5.
temperature range.
MAX
Note 1: To calculate maximum switch “on” voltage at currents between
low and high conditions, a linear interpolation may be used.
Note 7: Error amplifier voltage gain and transconductance are specified
relative to the internal feedback node. To calculate gain and
Note 2: A sense pin voltage (V
clamp level and the switch duty cycle to zero. This approximates the zero
load condition where duty cycle approaches zero.
) of 5.5V forces the V pin to its low
transconductance from the Sense pin (Output) to the V pin, multiply by
0.44.
Note 8: Does not include switch leakage.
SENSE
C
C
Note 3: Total voltage from V pin to ground pin must be ≥ 8V after start-
IN
R
– 1k
5k
LIM
Note 9: I
≈
LIM
up for proper regulation. For T < 25°C, limit = 5V.
A
Note 4: Switch frequency is internally scaled down when the sense pin
voltage is less than 2.6V to avoid extremely short switch on times. During
current limit testing, V
is adjusted to give a minimum switch on time
SENSE
of 1µs.
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
3
LT1076-5
U
Dimensions in inches (millimeters) unless otherwise noted.
R Package, 7-Lead Plastic DD
PACKAGE DESCRIPTIO
0.060
0.401 ± 0.015
(1.524)
(10.185 ± 0.381)
0.175 ± 0.008
0.050 ± 0.008
(4.445 ± 0.203)
(1.270 ± 0.203)
15° TYP
+0.008
0.004
+0.012
0.331
–0.004
0.059
(1.499)
TYP
–0.020
+0.203
–0.102
0.102
+0.305
(
)
8.407
(
)
–0.508
0.105 ± 0.008
(2.667 ± 0.203)
0.050 ± 0.010
(1.270 ± 0.254)
0.030 ± 0.008
(0.762 ± 0.203)
0.050 ± 0.012
(1.270 ± 0.305)
+0.012
–0.020
+0.305
–0.508
0.022 ± 0.005
(0.559 ± 0.127)
DD7 0693
0.143
3.632
(
)
T Package, 5-Lead TO-220
0.165 – 0.180
(4.293 – 4.572)
0.147 – 0.155
(3.734 – 3.937)
DIA
0.390 – 0.415
(9.906 – 10.541)
0.045 – 0.055
(1.143 – 1.397)
0.230 – 0.270
(5.842 – 6.858)
0.570 – 0.620
(14.478 – 15.748)
0.620
(15.75)
TYP
0.460 – 0.500
(11.684 – 12.700)
0.330 – 0.370
(8.382 – 9.398)
0.700 – 0.728
(17.780 – 18.491)
0.095 – 0.115
(2.413 – 2.921)
0.152 – 0.202
(3.860 – 5.130)
0.260 – 0.320
(6.604 – 8.128)
0.013 – 0.023
(0.330 – 0.584)
0.057 – 0.077
(1.448 – 1.956)
0.135 – 0.165
(3.429 – 4.191)
0.155 – 0.195
(3.937 – 4.953)
0.028 – 0.038
(0.711 – 0.965)
T5 (FORMED) 0694
Y Package, 7-Lead TO-220
0.390 – 0.410
(9.91 – 10.41)
0.147 – 0.155
(3.73 – 3.94)
DIA
0.169 – 0.185
(4.29 – 4.70)
0.045 – 0.055
(1.14 – 1.40)
0.235 – 0.258
(5.97 – 6.55)
0.103 – 0.113
(2.62 – 2.87)
0.560 – 0.590
(14.22 – 14.99)
0.620
(15.75)
TYP
0.700 – 0.728
(17.78 – 18.49)
0.152 – 0.202
(3.86 – 5.13)
0.260 – 0.320
(6.60 – 8.13)
0.026 – 0.036
(0.66 – 0.91)
0.095 – 0.115
(2.41 – 2.92)
0.155 – 0.195
(3.94 – 4.95)
0.016 – 0.022
0.045 – 0.055
(1.14 – 1.40)
(0.41 – 0.56)
0.135 – 0.165
(3.43 – 4.19)
Y7 0893
LT/GP 0794 5K REV A • PRINTE IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
4
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
LINEAR TECHNOLOGY CORPORATION 1994
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