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LT3487EDD#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
LT3487
1
3487f
Boost and Inverting
Switching Regulator
for CCD Bias
■
CCD Bias
■
TFT LCD Bias
■
OLED Bias
■
±Rail Generation for Op Amps
■
Generates 15V at 45mA, –8V at 90mA from a
Li-Ion Cell
■
Output Disconnect
■
Sequencing: Positive Output Reaches Regulation
Before Negative Channel Begins Switching
■
Internal Schottky Diodes
■
2MHz Constant Switching Frequency
■
Requires Only One Resistor per Channel to Set
Output Voltages
■
V
IN
Range: 2.3V to 16V
■
Output Voltage Up to 28V
■
Short-Circuit Robust
■
Capacitor Programmable Soft-Start
■
Separate V
BAT
Pin Allows Separate Sources for
Power and Control Circuitry
■
Available in 10-Lead (3mm × 3mm) DFN Package
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
The LT
®
3487 dual channel switching regulator generates
positive and negative outputs for biasing CCD imagers.
The device delivers up to –8V at 90mA and 15V at 45mA
from a lithium-ion cell, providing bias for many popular
CCD imagers. The boost regulator incorporates output
disconnect technology to eliminate the DC current path
from V
IN
to the output load that is present in standard
boost confi gurations. The 2MHz switching frequency
allows CCD solutions using tiny, low profi le capacitors
and inductors and generates low noise outputs that are
easy to fi lter. Schottky diodes are internal and the output
voltages are set with one resistor per channel, reducing
the external component count.
Intelligent soft-start allows sequential soft-start of the two
channels with a single capacitor. The soft-start is sequenced
such that the output ramp of the negative channel begins
after the ramp of the positive channel. Internal sequencing
circuitry also disables the negative channel until the positive
channel has reached 87% of its fi nal value, ensuring that
the sum of the two outputs is always positive.
The LT3487 is available in a 10-pin 3mm × 3mm DFN
package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
SWN
15µH10µH
V
IN
CAP
549k
FBP
V
POS
V
BAT
LT3487
GND
SWP
DN
15µH
324k
47pF
FBN
RUN/SSRUN/SS
V
NEG
–8V
90mA
100nF
4.7µF
3487 TA01a
100nF
V
POS
15V
45mA
1µF
2.2µF
22µF
V
IN
3V TO 12V
Conversion Effi ciency
LOAD CURRENT (mA)
0
EFFICIENCY (%)
55
60
65
60
100
3487 TA01b
50
45
40
20 40 80
70
75
80
POS CHANNEL AT CAP
NEG CHANNEL
POS CHANNEL
AT V
POS
V
IN
= 3.6V
LT3487
2
3487f
V
IN
Voltage ............................................................... 16V
V
BAT
Voltage ............................................................. 16V
SWP, SWN Voltage ................................................... 32V
CAP, V
POS
.................................................................30V
DN Voltage ............................................................. –32V
RUN/SS Voltage ..........................................................8V
FBP Voltage ................................................................ 6V
FBN Voltage ................................................ –0.2V to 6V
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range ................. –40°C to 85°C
Storage Temperature Range ................... –65°C to 125°C
ORDER PART NUMBER
DD PART MARKING
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
LBXB
LT3487EDD
(Note 1)
The
● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 3.6V, V
BAT
= 3.6V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Operating Voltage Range 2.3 16 V
Quiescent Current RUN/SS = 3V, Not Switching
RUN/SS = 0V
3.7
5.3
5
8
mA
µA
RUN/SS Voltage Threshold (Full Current) (Note 3) 1.6 V
RUN/SS Voltage Threshold (Shutdown)
●
100 160 mV
RUN/SS Pin Current RUN/SS = 0V (Note 4) 1 1.4 2 µA
FBP (Positive Channel) Pin Voltage
●
1.19 1.23 1.27 V
FBN (Negative Channel) Pin Voltage
●
–7 3 12 mV
FBP Pin Voltage Line Regulation 0.007 %/V
FBN Pin Voltage Line Regulation 0.001 mV/V
FBP Pin Bias Current
●
24.4 25 25.6 µA
FBN Pin Bias Current
●
24.4 25 25.6 µA
FBP Threshold (Percent of Final Value)
to Start Negative Channel
87 90 %
Switching Frequency 1.85 2 2.15 MHz
Maximum Duty Cycle
●
87 93 %
Positive Channel Switch Current Limit (Note 5)
●
750 920 mA
Negative Channel Switch Current Limit (Note 5)
●
900 1090 mA
Positive Channel V
CESAT
I
SWP
= 400mA 280 mV
Negative Channel V
CESAT
I
SWN
= 600mA 340 mV
ELECTRICAL CHARACTERISTICS
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
TOP VIEW
11
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
10
9
6
7
8
4
5
3
2
1
V
POS
FBP
RUN/SS
FBN
V
IN
CAP
SWP
V
BAT
SWN
DN
θ
JA
= 43°C/W, θ
JC
= 3°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE CONNECTED TO PCB
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
LT3487
3
3487f
TYPICAL PERFOR A CE CHARACTERISTICS
UW
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 3.6V, V
BAT
= 3.6V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Schottky DP Forward Drop I
SWP
= 400mA 1045 mV
Schottky DN Forward Drop I
SWN
= 600mA 980 mV
Disconnect PNP V
CE
I
VPOS
= 50mA 205 mV
Disconnect Current Limit V
CAP
= 15V, V
POS
= 0V 100 155 mA
V
CAP
– V
BAT
to Disconnect V
BAT
= 3.6V, V
POS
= 0V, I
CAP
< 100µA 1.2 1.6 V
Disconnect Leakage V
BAT
= 3.6V, CAP = 3.6V, V
POS
= 0V 0.1 1.0 µA
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 LT3487E is guaranteed to meet specifi ed performance from
0°C to 85°C. Specifi cations over the –40°C to 85°C operating range are
assured by design, characterization and correlation with statistical process
controls.
Shutdown Quiescent Current Positive Output to Enable Inverter FBP Voltage
Note 3: Guaranteed by design, not directly tested.
Note 4: Current fl ows out of pin.
Note 5: Current limit guaranteed by design and/or correlation to static test.
Slope compensation reduces current limit at higher duty cycle.
TEMPERATURE (°C)
–50 –25
0
QUIESCENT CURRENT (µA)
4
10
0
50
75
3487 G01
2
8
6
25
100
125
TEMPERATURE (°C)
–50 –25
50
PERCENTAGE OF FINAL FBP VOLTAGE (%)
70
100
0
50
75
3487 G02
60
90
80
25
100
125
TEMPERATURE (°C)
–50
1.200
V
FBP
(V)
1.225
1.250
1.275
1.300
–25 0 25 50
3487 G03
75 100 125
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

LT3487EDD#TRPBF

Mfr. #:
Buy LT3487EDD#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 2MHz, Boost /Inverting DC/DC Converter for CCD Bias in DFN
Lifecycle:
New from this manufacturer.
Delivery:
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