LX2173CP-TR [MICROSEMI]
Switching Regulator, Current-mode, 2.8A, 115kHz Switching Freq-Max, PSFM5, PLASTIC, TO-220, 5 PIN;
| 型号： | LX2173CP-TR |
| 厂家： | 
Microsemi |
| 描述： | Switching Regulator, Current-mode, 2.8A, 115kHz Switching Freq-Max, PSFM5, PLASTIC, TO-220, 5 PIN 局域网 开关 |
| 文件： | 总6页 (文件大小：256K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LX2172 / 73
1.25A HIGH-EFFICIENCY 100KH
Z
SWITCHING
REGULATOR
P
R E L I M I N A R Y
D
A T A H E E T
S
T
H E
I
N F I N I T E
P
O W E R O F
I N N O V A T I O N
KEY FEATURES
DESCRIPTION
The LX2172/73 are fixed-frequency,
current-mode switching regulator integrated also be used in forward and inverting
circuits. These ICs contain all necessary converter configuations.
control circuitry plus a 1.25A on-board
transistor to design a complete DC:DC external clock for synchronization, and can
switching regulator with minimum external enter micropower operation when the VC
boost and flyback applications, but can
1.25A, 65V Internal Power
Switch
3V - 25V Input Voltage Range
Current-Mode Operation
Improved Internal Cycle-By-
Cycle Current Limiting
Thermal Shutdown
Less Than 10µA Quiescent
Current In Microprocessor
Shutdown Mode
The LX2172 can be connected to an
components.
pin is pulled low. The LX2173 has an
All functions are integrated into a single enable function, which permits extremely
IC, available in 8-pin DIP and SOIC or a 5- low micropower operation, consuming
pin TO-220 power package, making them under 10µA current when the ENABLE
extremely easy to design with and use. The pin is brought low
External Frequency
Synchronization Possible
100kHz Operating Frequency
LX2172/73 are optimized for
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
APPLICATIONS
Boost Converter
PRODUCT HIGHLIGHT
Laptop / Notebook Computers
Portable Equipment
Small Motor Applications
Flyback Converters
SEPIC CONVER TER
U
SING
THE LX2172
Input 6-24V, Output 7V, 300mA
VIN
6-24V DC
Output
7V
300mA
Part #
Pin 4 Connection
C2
330 µF
LX2172
SYNC Input
D1
L1
7V
Low µPower Mode
(Hi ENABLE)
1mH
LX2173
C1
C3
1N5817
U1
COUT
220 µF
22µF
0.1µF
1
2
3
4
8
7
6
5
GND
E
2
R
13.7k
1
VC
VSW
FB
E
C4
0.47 µF
1
L2
1mH
SYNC
VIN
(See Note 1)
CDECOUPLE
0.47 µF
R
R
2
3
3.0k
100
Note 1: SYNC Pin Requirements:
A) FMAX = 200kHz
B) TTL Compatible Level
C) Pulse Width T Range - 0.1µs < TP < 2.0µs
P
PACKAGE ORDER INFO
Plastic DIP
8-Pin
Plastic SOIC
Plastic TO-220
5-Pin
M
DM
P
8-Pin
TA (°C)
RoHS Compliant / Pb-free
Transition DC: 0503
RoHS Compliant / Pb-free
Transition DC: 0440
0 to 70
LX217xCM
LX217xCDM
LX217xCP
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX2172CDM-TR)
L
I N
F
I N I T Y
M
I C R O E L E C T R O N I C S
I N C .
Copyright © 1998
Rev. 0.4a ,2005-03-09
1
11861 WESTERN
A
VENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: 714-893-2570
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
LX2172/73
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
P R E L I M I N A R Y D A T A S H E E T
PACKAGE PIN OUTS
ABSOLUTE MAXIMUM RATINGS (Note 1)
Supply Voltage (VIN) .................................................................................................... 25V
Collector Supply Voltage (VC) ..................................................................................... 65V
Digital Inputs (SYNC) .........................................................................................-0.3 to 7V
Operating Junction Temperature ................................................................. 0°C to 125°C
Storage Temperature Range .................................................................... -65°C to +150°C
Solder Temperature (Soldering, 10 seconds) .......................................................... 300°C
Pb-free / RoHS Peak Package Solder Reflow Temp (40 second max. exposure)................. 260°C (+0, -5)
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect
GND
VC
FB
1
2
3
4
8
7
6
5
E2
VSW
E1
* SYNC / ENABLE
VIN
M PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
to Ground. Currents are positive into, negative out of the specified terminal.
1
2
3
4
8
7
6
5
GND
VC
FB
E2
VSW
E1
THERMAL DATA
M PACKAGE:
* SYNC / ENABLE
VIN
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
DM PACKAGE:
95°C/W
DM PACKAGE
(Top View)
* Pin 4 = SYNC for LX2172, ENABLE for LX2173/2174
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
P PACKAGE:
165°C/W
RoHS / Pb-free 100% Matte Tin Lead Finish
TAB IS GND
THERMAL RESISTANCE-JUNCTION TO TAB, θJT
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
4.5°C/W
60°C/W
VIN
VSW
5
GND
FB
VC
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow.
1
P PACKAGE
(Top View)
BLOCK DIAGRAM
V
I
N
V
I
N
V
I
N
5
E
C
N
A
B
L
E
O
M
P
1
.
4
V
V
U
R
E
G
V
L
O
C
O
M
P
G
N
D
V
2
.
3
V
E
N
R
E
G
1
V
R
E
G
2
.
3
V
(
N
O
T
E
1
)
E
N
A
B
L
E
V
7
O
S
C
.
D
.
S
W
V
O
O
M
P
0
.
1
5
V
E
.
A
.
1
.
2
7
V
P
C
W
M
P
W
M
g
O
M
P
L
A
T
C
H
Q
1
Q
2
M
F
B
R
Q
Q
3
2
S
V
C
V
O
F
S
(
0
.
9
V
)
1
.
4
V
1
0
0
k
H
z
C
.
S
.
A
M
P
2
5
0
m
V
E
N
1
0
0
k
H
z
S
L
O
P
E
C
O
M
P
O
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I
N
(
N
O
T
E
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6
8
S
Y
N
C
E
1
E
2
Note 1: LX2172 Only: SYNC brought out to pin 4. ENABLE is tied to VIN. LX2173 Only: ENABLE brought out to pin 4. SYNC is open.
Copyright © 1998
Rev. 0.4a 12/04
2
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
LX2172/73
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
P R E L I M I N A R Y D A T A S H E E T
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the ranges TA = 0 to 70ºC for the LX217xC. VIN = VC = 5V. All devices must be functional over
junction temperature of -65°C to 150°C. Typ. number represents TA = 25ºC value.)
LX2172 / 2173
Parameter
Reference Section
Symbol
Test Conditions
Units
Min. Typ.
Max.
Initial Accuracy
TJ = 25ºC, Measured at FB pin
Over Temperature, Measured at FB pin
3V < VCC < 25V
1.224 1.244 1.264
1.214 1.244 1.274
0.03
V
V
VREF
Line Regulation
% / V
Oscillator Section
Switching Frequency
TA = 25ºC
90
85
100
100
110
115
5
kHz
kHz
%
f
Over Temperature
VIN = 3V to 25V
Line Voltage Stability
Error Amplifier Section
Input Bias Current
TJ = 25ºC; VFB = VREF
Over Temperature
350
750
1100
1000
6000 ꢀMHO
7000 ꢀMHO
nA
nA
IB
Open Loop Gain
Transconductance
AVOL
gm
500
4400
V / V
3000
2400
120
120
1.8
TJ = 25ºC; VFB = VREF; ∆I = 25ꢀA
Over Temperature
200
ꢀA
ꢀA
Output Sink Current
Output Source Current
Output HI Voltage
Output LO Voltage
Slew Rate
IEA (SINK)
IEA (SOURCE)
2.1
0.3
2
2.3
0.52
V
V
VCOMP-HI VFB = 1V
VCOMP-LO VFB = 1.5V
S
0.2
V/ꢀsec
C.S. Comparator Section
C.S. Delay to Driver Output
VC to Output Transconductance
10% Over drive GBNT
100
2
ns
A / V
PWM Section
E.A. Output to PWM Drive Offset (VPWM)
Minimum Duty Cycle
VOFS
Duty Cycle = 0
0.6
80
1.2
36
90
1.25
40
98
V
%
%
Maximum Duty Cycle
Output Drive Section
Output Switch Breakdown Voltage
Output Switch On Resistance
Switch Current Limit
ISW = 1.5mA
65
V
Ω
RON
ILIM
IO = 2A
D.C = 50%
0.4
1.7
1.5
100
0.6
2.8
2.0
1.25
1.0
A
50% < D.C < 80%
A
mW
Total Switching Loss (On Time + Off Time)
VIN = 25V, D.C = 50%, IO = 1A, VSW = 60V
Input Supply Section
Start-Up Threshold
Normal Mode Quiescent Current
VC Shutdown Threshold
2.2
2.7
5
2.9
8
V
IQ
ENABLE = HI, VC = 0.6V, IO = 0A
3V < VIN < VMAX , TJ = 25°C
mA
mV
mV
ꢀA
ꢀA
100
50
150
260
300
3V < VIN < VMAX , Over Temperature
ENABLE = HI, VC = 50mV
Sleep Mode Current
100
5
ENABLE = LO (LX2173 only)
Copyright © 1998
Rev. 0.4a 12/04
3
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
LX2172/73
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
P R E L I M I N A R Y D A T A S H E E T
ELECTRICAL CHARACTERISTICS
LX2172 / 2173
Parameter
Symbol
Test Conditions
Units
Min. Typ.
Max.
SYNC Input Section (LX2172 only)
SYNC Pulse Width
SYNC Input HI
0.2
2
2
6
ꢀsec
V
SYNC Input LO
0.7
400
5
V
SYNC Input Current HI
SYNC Input Current LO
Input = 2V
Input = 0.4V
100
1
ꢀA
ꢀA
ENABLE Section (LX2173 only)
Enable Input Threshold
HI Input Current
0.4
1.2
2.4
200
100
V
Input = 2.4V
Input = 0.4V
ꢀA
ꢀA
LO Input Current
FUNCTIONAL PIN DESCRIPTION
Name (8-pin Pkgs.) (5-pin TO-220) Description
Pin
Pin #
Pin #
GND
VC
1
2
3
1
Signal ground. Keep separate from power grounds (E1 and E2).
Output of transconductance error amplifier. An R-C compensation network is connected from
this pin to the ground to stabilize the feedback loop. If this pin is pulled lower than 0.15V, the
IC goes into micropower mode.
FB
3
4
2
Error amplifier inverting input. A resistor divider from the output of the converter to this pin sets
its nominal voltage.
SYNC
LX2172 only. This pin is used to synchronize the device directly with a logic level input pulse.
External synchronization frequency must always be at a higher frequency than the minimum
internal clock. When not used, should be left open.
ENABLE
VIN
4
LX2173 only. This pin is the input to the enable comparator. A voltage under 1.4V will put the
device in micropower mode. Pin must be connected to VIN when not in use.
5
6
7
5
4
Input supply voltage (3.0V to 25V).
E
Power return of first transistor (Q1). This pin must be connected to ground.
1
VSW
Collectorofoutputtransistors. Connecttoexternalinductororinputvoltage,dependingoncircuit
topology.
E
8
Groundingthispinsetsthecurrentlimitpointtothemaximumvalue. Ifpinisleftopen,thecurrent
limit is set to half its maximum value.
2
Copyright © 1998
Rev. 0.4a 12/04
4
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
LX2172/73
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
P R E L I M I N A R Y D A T A S H E E T
THEORY OF OPERATION
IC OPERATION
OSCILLATOR
Referring to the block diagram, when VIN is above the UVLO
start threshold the 2.3V UVLO comparator output switches to
low state, allowing Q1 to turn on upon receiving a clock pulse
from the internal 100kHz oscillator. Once Q1 is on, current in
the inductor ramps up. Inductor current is then sensed, and
amplified by a current sense amplifier and compared to a thresh-
old set by the output of the error amplifier minus the offset
voltage (VOFS typically 0.9V). This allows the PWM comparator
to reset the flip flop, causing Q1 to turn off. The oscillator then
sets the flip flop, and the operation repeats itself.
The oscillator is designed to operate at 100kHz frequency. Its
function is to turn the switch Q1 on at a fixed 10µs interval and
to provide a slope compensation for the feedback loop. Slope
compensation is required for fixed frequency continuous Cur-
rent Mode regulators operating above 50% duty cycle in order
to prevent loop instability. The SYNC input is a logic input that
allows easy synchronization to an external clock. Synchroniza-
tion is done such that the external clock terminates the cycle
before the internal oscillator sets the PWM latch again.
UNDER-VOLTAGE LOCKOUT
CURRENT LIMIT
The 2.3V internal regulator is monitored as the input supply
ramps up, ensuring glitch-free operation.
Current limiting is performed by sensing the peak switch cur-
rent and turning Q1 off until the next clock cycle. When the
converter goes into current limit the error amplifier output goes
to the rail and sets a maximum limit on the current.
EXTRA PINS ON 8-PIN DEVICE
The 8-pin versions of the LX217x have the emitters of the power
transistors brought out separately. Connecting these pins to
ground reduces errors due to ground pin voltage drops. The E2
pin also allows the user to half the switch current limit if the pin
is left open. Note that the switch resistance will increase when
E2 is open, so efficiency will decrease and heat dissipation will
increase, especially for currents over 300mA.
ERROR AMPLIFIER
The function of the error amplifier is to set a threshold voltage
for inductor peak current and control the switch duty cycle so
that the power supply output voltage is closely regulated. Regu-
lation is accomplished by sensing the output voltage and com-
paring it to the internal 1.27V bandgap reference. A compensa-
tion network is placed from the output of the amplifier to ground
for closed loop stability purposes, as well as a high d.c. gain for
tight regulation. The function of VOFS is to keep Q1 off without
requiring an error amplifier output to swing to ground level. It
is required the VOL of the error amplifier is always less than the
offset at all times. The transfer function between the error
amplifier output (VC) and peak inductor current is therefore
given by:
MICROPOWER SHUTDOWN
The LX2172/73 enter micropower shutdown mode when the VC
pin is pulled below 0.15V. Supply current required for biassing
shutdown circuitry is less than 250µA. The LX2173 has an EN-
ABLE pin which allows ultra-low micropower shutdown opera-
tion, consuming less than 10µA.
VC - VOFS = IP
G R
*
S
*
Where: IP = Inductor peak current
G = Current sense gain (typically 6)
RS = Internal sense resistor
Copyright © 1998
Rev. 0.4a 12/04
5
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
LX2172/73
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
P R E L I M I N A R Y D A T A S H E E T
THEORY OF OPERATION
V
IN
+3V to +12V
22µF
180µH
1
2
3
4
8
7
6
5
GND
VC
E
2
VOUT
1N5817
VOUT
VSW
14.7kΩ
1.27Ω
+16V
LX2172
FB
E
1
0.03µF
SYNC
V
V
IN
IN
100Ω
V
IN
FIGURE 1 — Boost Coverter Circuit Using The LX2172 / 2173
PRELIMINARY DATA - Information contained in this document is pre-production data, and is proprietary to Linfinity. It may
not modified in any way without the express written consent of Linfinity. Product referred to herein is offered in sample form
only, and Linfinity reserves the right to change or discontinue this proposed product at any time.
Copyright © 1998
Rev. 0.4a 12/04
6
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