LT3469ETS8#TRPBF [Linear]
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| 型号： | LT3469ETS8#TRPBF |
| 厂家： | 
Linear |
| 描述： | 暂无描述 驱动器 稳压器 光电二极管 |
| 文件： | 总8页 (文件大小：166K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT3469
Piezo Microactuator Driver
with Boost Regulator
U
FEATURES
DESCRIPTIO
TheLT®3469isatransconductance(gm)amplifierthatcan
drive outputs up to 33V from a 5V or 12V supply. An
internal switching regulator generates a boosted supply
voltage for the gm amplifier. The amplifier can drive
capacitive loads in the range of 5nF to 300nF. Slew rate is
limited only by the maximum output current. The 35V
output voltage capability of the switching regulator, along
with the high supply voltage of the amplifier, combine to
allow the wide output voltage range needed to drive a
piezoceramic microactuator.
Amplifier
■
Current Limit: ±40mA Typical
■
Input Common Mode Range: 0V to 10V
■
Output Voltage Range: 1V to (VCC – 1V)
■
Differential Gain Stage with High Impedance Output
(gm Stage)
■
Quiescent Current (from VCC): 2mA
■
Unloaded Gain: 30,000 Typical
Switching Regulator
■
Generates VCC Up to 35V
■
Wide Operating Supply Range: 2.5V to 16V
The LT3469 switching regulator switches at 1.3MHz,
allowing the use of tiny external components. The output
capacitorcanbeassmallas0.22µF, savingspaceandcost
versus alternative solutions.
■
High Switching Frequency: 1.3MHz
Internal Schottky Diode
Tiny External Components
Current Mode Switcher with Internal Compensation
Low Profile (1mm) SOT-23 Package
■
■
■
TheLT3469isavailableinalowprofileThinSOTTM package.
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
U
APPLICATIO S
■
Piezo Speakers
■
Piezo Microactuators
■
Varactor Bias
U
TYPICAL APPLICATIO
Piezo Microactuator Driver
47µH
5V OR 12V
Response Driving a 33nF Load
3
5
1µF
16V
V
SW
IN
IOUT
6
2
V
100mA/DIV
CC
453k
0.47µF
FB
50V
VOUT
10V/DIV
LT3469
16.5k
4
1
GND
OUT
9.09k
7
8
+
–
+IN
–IN
V
OUT
1V TO 33V
+
INPUT
5V/DIV
INPUT
0V TO 3V
50µs/DIV
3469 TA04
10k
PIEZO
ACTUATOR
5nF < C < 300nF
–
100k
3469 TA03
3469f
1
LT3469
W W
U W
U W
U
ABSOLUTE AXI U RATI GS
(Note 1)
PACKAGE/ORDER I FOR ATIO
ORDER PART
VIN Voltage ............................................................. 16V
SW Voltage ............................................................. 40V
TOP VIEW
NUMBER
OUT 1
FB 2
8 –IN
7 +IN
6 V
CC
V
CC Voltage............................................................. 38V
LT3469ETS8
V
3
+IN, –IN Voltage ..................................................... 10V
FB Voltage ................................................................ 3V
Current Into SW Pin ................................................. 1A
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
IN
GND 4
5 SW
TS8 PART MARKING
LTACA
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
TJMAX = 125°C, θJA = 250°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2) VIN = 5V, VCC = 35V, unless otherwise noted.
PARAMETER
Amplifier
CONDITIONS
MIN
TYP
MAX
UNITS
g
m
Input Offset Voltage
V
= V /2
●
●
●
3
10
mV
nA
OUT
CC
Input Offset Current
10
100
500
Input Bias Current
150
1
nA
Input Resistance—Differential Mode
Input Resistance—Common Mode
Common Mode Rejection Ratio
MΩ
MΩ
dB
200
100
120
85
V
V
V
= 0V to 10V
70
80
65
CM
Power Supply Rejection Ratio—V
Power Supply Rejection Ratio—V
Gain
= 2.5V to 16V
= 15V to 35V
dB
IN
IN
dB
CC
CC
No Load, V
R = 200k, V
= 2V to 33V
15
10
30
20
V/mV
V/mV
OUT
= 2V to 33V
OUT
L
Transconductance
I
= ±100µA
160
140
220
260
300
µA/mV
µA/mV
OUT
●
●
Maximum Output Current
V
= V /2
±30
±23
±40
±55
±58
mA
mA
OUT
CC
Maximum Output Voltage, Sourcing
Minimum Output Voltage, Sinking
Output Resistance
V
V
= 35V, I
= 35V, I
= 10mA
= 0mA
34.0
34.5
34.5
34.9
V
V
CC
CC
OUT
OUT
I
I
= –10mA
= 0mA
200
10
1000
500
mV
mV
OUT
OUT
V
V
= 35V, V
= 35V
= 2V to 33V
OUT
100
2
kΩ
CC
CC
Supply Current—V
1.5
2.5
2.5
mA
CC
Switching Regulator
Minimum Operating Voltage
Maximum Operating Voltage
Feedback Voltage
V
V
16
●
●
1.19
1.23
45
1.265
200
V
FB Pin Bias Current
nA
FB Line Regulation
2.5V < V < 16V
0.03
1.9
1.3
91
%/V
mA
MHz
%
IN
Supply Current—V
2.6
1.7
IN
Switching Frequency
●
●
●
0.8
88
Maximum Duty Cycle
Switch Current Limit (Note 3)
165
220
350
mA
mV
Switch V
I
= 100mA
SW
500
CESAT
3469f
2
LT3469
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2) VIN = 5V, VCC = 35V, unless otherwise noted.
PARAMETER
CONDITIONS
= 5V
MIN
TYP
0.01
740
0.1
MAX
1
UNITS
µA
Switch Leakage Current
V
SW
Diode V
I = 100mA
D
1100
1
mV
F
Diode Reverse Leakage Current
V = 5V
R
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at higher duty cycles.
Note 2: The LT3469E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
U W
TYPICAL PERFOR A CE CHARACTERISTICS
(Switching Regulator)
VIN Quiescent Current
Current Limit vs Duty Cycle
Schottky Forward Voltage
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
250
200
150
100
50
250
T
= 25°C
A
–50°C
200
150
100°C
25°C
25°C
100°C
100
50
0
–50°C
0
6
8
0
2
4
10 12 14 16
600
700 800 900 1000
0
20
40
60
80
100
200 300 400 500
V
IN
(V)
DUTY CYCLE (%)
FORWARD VOLTAGE (mV)
3469 G05
3469 G06
3469 G07
Switching Frequency
FB Pin Voltage and Bias Current
Schottky Reverse Leakage
1.275
1.255
1.235
1.215
50
40
30
20
25
20
15
10
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
= 5V
R
CURRENT
VOLTAGE
1.195
1.175
10
0
5
0
–50
0
25
50
75
100
–25
–50
0
25
50
75
100
–50 –25
0
25
50
75
100
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
3469 G11
3469 G09
3469 G10
3469f
3
LT3469
U W
TYPICAL PERFOR A CE CHARACTERISTICS
(gm Amplifier)
Output Current
vs Differential Input Voltage
VCC Quiescent Current
gm vs VCC
2.5
2.0
1.5
1.0
0.5
0
30
25
250
200
150
100
50
100°C
–50°C
100°C
25°C
20
25°C
15
–50°C
10
5
0
–5
100°C
–50°C
25°C
–10
–15
–20
–25
–30
0
15
18
21
24
V
27
(V)
30
33
36
–50 –40 –30 –20 –10
0
10 20 30 40 50
15
20
25
(V)
30
35
DIFFERENTIAL INPUT VOLTAGE (mV)
V
CC
CC
3469 G01
3469 G02
3469 G14
U
U
U
PI FU CTIO S
OUT (Pin 1): Output of the gm Amplifier. There must be at
least 5nF of capacitive load at the output in a gain of 10
configuration. Capacitive loads up to 300nF can be con-
nectedtothispin. Piezoactuatorsbelow5nFcanbedriven
if capacitance is placed in parallel to bring the total
capacitance to 5nF.
GND (Pin 4): Ground Pin. Connect directly to local ground
plane.
SW (Pin 5): Switch Pin. Connect inductor here. Minimize
trace area at this pin to reduce EMI.
VCC (Pin 6): Output of Switching Regulator and Supply
Rail for gm Amp. There must be 0.22µF or more of
capacitance here.
FB (Pin 2): Feedback Pin. Reference voltage is 1.23V.
Connect feedback resistor divider here.
+IN (Pin 7): Noninverting Terminal of the gm Amplifier.
–IN (Pin 8): Inverting Terminal of the gm Amplifier.
VIN (Pin 3): Input Supply Pin. Must be locally bypassed.
W
BLOCK DIAGRA
SW
V
V
V
CC
IN
IN
5
V
CC
+IN
7
3
FB
2
6
+
–
–
+
OUT
1
SWITCH
CONTROLLER
g
A1
Q1
m
–IN
8
1.23V
4
3469 F01
GND
Figure 1. LT3469 Block Diagram
3469f
4
LT3469
U
OPERATIO
gm Amplifier
cal bandwidth of a gain of 10 configuration per output
capacitance.
The LT3469 is a wide output voltage range gm amplifier
designed to drive capacitive loads. Input common mode
range extends from 10V to ground. The output current is
proportional to the voltage difference across the input
terminals. When the output voltage has settled, the input
terminals will be at the same voltage; supply current of the
amplifier will be low and power dissipation will be low. If
presented with an input differential, however, the output
current can increase significantly, up to the maximum
output current (typically 40mA). The output voltage slew
rateisdeterminedbythemaximumoutputcurrentandthe
output capacitance, and can be quite high. With a 10nF
load, the output slew rate will typically be 4V/µs. The
capacitiveloadcompensatesthegm amplifierandmustbe
presentforstableoperation. Thegaincapacitanceproduct
of the amplifier must be at least 50nF. For example, if the
amplifier is operated in a gain of 10 configuration, a
minimum capacitance of 5nF is necessary. In a gain of 20
configuration, a minimum of 2.5nF is necessary. Closed
loop –3dB bandwidth is set by the output capacitance.
Typical closed loop bandwidth is approximately:
In applications where negative phase contributions below
crossover frequency must be minimized, a phase boost
capacitor can be added, as shown in Figure 4. Larger val-
ues of CBOOST will further reduce the closed-loop negative
phase contribution, however, the amplifier phase margin
will be reduced. For an amplifier phase margin of approxi-
mately 55°, select CBOOST as follows:
COUT R1/ R2 + 1
(
)
CBOOST
=
g R1||R2
(
)
m
where gm = 200µA/mV.
In a gain of 10 configuration, choosing CBOOST as de-
scribed will lead to nearly zero closed-loop negative phase
contribution at 3kHz for values of COUT from 10nF to
200nF. The phase boost capacitor should not be used if
C
OUT is less than twice the minimum for stable operation.
The gain capacitance product should therefore be higher
than 100nF if a phase boost capacitor is used.
Switching Regulator
gm
2π • AV •COUT
The LT3469 uses a constant frequency, current mode
control scheme to provide excellent line and load regula-
tion. Operation can be best understood by referring to the
Block Diagram in Figure 1. The switch controller sets the
peakcurrentinQ1proportionaltoitsinput.Theinputtothe
switch controller is set by the error amplifier, A1, and is
where gm = 200µA/mV
Forexample, anamplifierinagainof10configurationwith
10nF of output capacitance will have a closed loop –3dB
bandwidth of approximately 300kHz. Figure 3 shows typi-
1000
100
10
1
WITH PHASE
BOOST CAPACITOR
WITHOUT PHASE
100
BOOST CAPACITOR
10
2
20
200
0.1
CAPACITANCE (nF)
2
20
200
3469 F03
CAPACITANCE (nF)
3469 F02
Figure 3. Closed Loop –3dB Bandwidth
vs Capacitance in a Gain of 10 Configuration
Figure 2. Slew Rate vs Capacitance
3469f
5
LT3469
U
OPERATIO
90
85
80
75
70
65
60
55
50
45
40
V
V
= 12V
IN
OUT
= 35V
+
–
INPUT
g
V
OUT
m
R1
R2
C
BOOST
3469 F04
MURATA LQH32CN470
SUMIDA CMD4011-470
TAIYO YUDEN LBC2518T470M
Figure 4. Boosting the Bandwidth of the gm Amplifier
with Capacitance On the Inverting Input
0
5
15
20
25
30
10
LOAD CURRENT (mA)
simply an amplified version of the difference between the
feedback voltage and the reference voltage of 1.23V. In
this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the error
amplifier’s output increases, more current is delivered to
the output; if it decreases, less current is delivered. The
switching regulator provides the boosted supply voltage
for the gm amplifier.
3469 F05
Figure 5. Efficiency Comparison of Different Inductors
transientresponse,however,moreoutputcapacitancecan
help limit the voltage droop on VCC during transients.
Table 2. Recommended Ceramic Capacitor Manufacturers
MANUFACTURER
Taiyo Yuden
AVX
PHONE
URL
408-573-4150
843-448-9411
814-237-1431
408-986-0424
www.t-yuden.com
www.avxcorp.com
www.murata.com
www.kemet.com
Inductor Selection
Murata
A 47µH inductor is recommended for most LT3469 appli-
cations. Some suitable inductors with small size are listed
in Table 1. The efficiency comparison of different induc-
tors is shown in Figure 5.
Kemet
Inrush Current Considerations When Hot Plugging
Table 1. Recommended Inductors
CURRENT
When the supply voltage is applied to VIN, the voltage
difference between VIN and VCC generates inrush current
flowing from the input through the inductor, the SW pin,
and the integrated Schottky diode to charge the output
capacitor. Care should be taken not to exceed the LT3469
maximumSWpincurrentratingof1A. Worst-caseinrush
current occurs when the application circuit is hot plugged
into a live supply with a large output capacitance. The
typical application circuit will maintain a peak SW pin
current below 1A when it is hot plugged into a 5V supply.
To keep SW pin current below 1A during a hot plug into
a 12V supply, 4.7Ω must be added between the supply
andtheLT3469inputcapacitor.Duringnormaloperation,
the SW pin current remains significantly less than 1A.
DCR
RATING
(mA)
PART NUMBER
(Ω)
MANUFACTURER
LQH32CN470
1.3
2.8
1.9
170
180
150
Murata
814-237-1431
www.murata.com
CMD4D11-470
LBC2518T470M
Sumida
847-545-6700
www.Sumida.com
Taiyo Yuden
408-573-4150
www.t-yuden.com
Capacitor Selection
The small size of ceramic capacitors makes them ideal for
LT3469applications.X5RandX7Rtypesarerecommended
becausetheyretaintheircapacitanceoverwidervoltageand
temperature ranges than other types such as Y5V or Z5U.
A 1µF input capacitor is sufficient for most LT3469 appli-
cations. A 0.22µF output capacitor is sufficient for stable
Layout Hints
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
Tomaximizeefficiency, switchriseandfalltimesaremade
3469f
6
LT3469
U
OPERATIO
as short as possible. To prevent electromagnetic interfer-
ence (EMI) problems, proper layout of the high frequency
switching path is essential. The voltage signal of the SW
pin has sharp rise and fall edges. The SW pin should be
surrounded on three sides by metal connected to VCC to
shield +IN and –IN. Minimize the area of all traces con-
nected to the SW pin and always use a ground plane under
theswitchingregulatortominimizeinterplanecoupling.In
addition, the ground connection for the feedback resistor
R1 should be tied directly to the GND pin and not shared
with any other component, ensuring a clean, noise-free
connection. The ground return of the piezoceramic
microactuator should also have a direct and unshared
connection to the GND pin. The GND connection to R5
should be tied directly to the ground of the source gener-
ating the INPUT signal to avoid error induced by voltage
drops along the GND line. Recommended component
placement is shown in Figure 6.
input, power dissipation is calculated from the amplifier
quiescent current (IQ), input frequency (f), output swing
(VOUT(P-P)), capacitive load (CL), amplifier supply voltage
(VCC) and switching regulator efficiency (η) as follows:
I + fVOUT(P-P)CL
V
CC
(
)
)
(
Q
PD =
η
Example: LT3469 at TA = 70°C, VCC = 35V, CL = 200nF,
f = 3kHz, VOUT(P-P) = 4V, η = 80%:
2.5mA + 3kHz • 4V • 200nF 35V
(
)(
)
PD =
= 214mW
0.80
T = 70°C + 214mW • 250°C/W = 124°C
J
Do not exceed the maximum junction temperature of
125°C.
GND INPUT
R5
R4
R3
Thermal Considerations and Power Dissipation
The LT3469 combines large output drive with a small
package. Because of the high supply voltage capability, it
is possible to operate the part under conditions that
exceed the maximum junction temperature. Maximum
junction temperature (TJ) is calculated from the ambient
temperature (TA) and power dissipation (PD) as follows:
R1
C1
R2
PIEZ0
ACTUATOR
C2
L
V
IN
TJ = TA + (PD • 250°C/W)
3469 F06
VIAS TO GROUND PLANE
Worst-case power dissipation occurs at maximum output
swing, frequency, capacitance and VCC. For a square wave
Figure 6. Recommended Component Placement
U
TYPICAL APPLICATIO
Piezo Speaker Driver
C1, C2: X5R OR X7R DIELECTRIC
L1: MURATA LQH32CN470
L1
47µH
V
SOUND PRESSURE LEVEL: 87dB AT 750Hz/10V /10cm
IN
3V TO 6V
P-P
WITH A 55nF PIEZO SPEAKER. I WITH V = 3.3V:
3
5
VIN
IN
C1
1µF
24mA AT 750Hz/10V WITH A 55nF PIEZO SPEAKER
P-P
V
SW
IN
6
2
V
CC
294k
C2
0.47µF
35V
FB
LT3469
17.4k
4
1
GND
OUT
16.9k
V
OUT
1V TO 20V
7
8
PIEZO
SPEAKER
8nF < C < 300nF
+IN
–IN
+
–
+
INPUT
0V TO 3V
20k
–
3469 TA01
113k
3469f
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.
7
LT3469
U
PACKAGE DESCRIPTIO
TS8 Package
8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1637)
0.52
MAX
0.65
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.50 – 1.75
(NOTE 4)
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
PIN ONE ID
0.22 – 0.36
8 PLCS (NOTE 3)
0.65 BSC
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.80 – 0.90
0.09 – 0.20
(NOTE 3)
0.20 BSC
NOTE:
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
1.95 BSC
TS8 TSOT-23 0802
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
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3469f
LT/TP 0304 1K • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
8
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003
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LT3470A - Micropower Buck Regulator with Integrated Boost and Catch Diodes; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C
Linear
LT3470AIDDB#TRPBF
LT3470A - Micropower Buck Regulator with Integrated Boost and Catch Diodes; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C
Linear
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