LTC1682/LTC1682-3.3/LTC1682-5
Doubler Charge Pumps with
Low Noise Linear Regulator
FEATURES
s
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DESCRIPTIO
Low Output Noise: 60
µ
V
RMS
(100kHz BW)
Adjustable or Fixed Boosted Output
Adjustable Output Voltage Range: 2.5V to 5.5V
Fixed Output Voltages: 3.3V, 5V
Wide Input Voltage Range: 1.8V to 4.4V
Uses Small Ceramic Capacitors
No Inductors Required
Output Current up to 50mA
550kHz Switching Frequency
Low Operating Current: 150µA
Low Shutdown Current: 1µA
Internal Thermal Shutdown and Current Limiting
Available in 8-Pin MSOP and SO Packages
APPLICATIO S
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VCO Power Supplies in Cellular Phones
2-Way Pagers
Wireless PCMCIA Cards
Portable Medical Instruments
Low Power Data Acquisition
Remote Transmitters
The LTC
®
1682/LTC1682-3.3/LTC1682-5 are doubler charge
pumps with an internal low noise, low dropout (LDO) linear
regulator. These parts are designed to provide a low noise
boosted supply voltage for powering noise sensitive devices
such as high frequency VCOs in wireless applications.
An internal doubler charge pump converts a 1.8V to 4.4V
input to a boosted output, while the internal LDO regulator
converts the boosted voltage to a low noise regulated output.
The adjustable version allows the user to set V
OUT
via external
resistors connected to FB. The regulator is capable of supply-
ing up to 50mA of output current. Shutdown reduces the
supply current to < 5µA, removes the load from V
IN
by
disabling the regulator and discharges V
OUT
to ground
through a 100Ω switch.
The LTC1682 LDO regulator is stable with only 2µF on the
output. Small ceramic capacitors can be used, reducing PC
board area.
The LTC1682/LTC1682-3.3/LTC1682-5 are short-circuit and
over temperature protected. The parts are available in 8-pin
MSOP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
4.2V VCO Power Supply, V
IN
= 2.5V to 4.4V
SHUTDOWN
8
4.7µF
7
V
IN
2.5V TO
4.4V
6
0.22µF
4.7µF
5
C
–
GND
4
C
+
V
IN
SHDN
LTC1682
FB
36k
3
15k
1µF
1k
1000pF
1000pF
4.7µF
1682 TA01
CPO
V
OUT
1
2
4.2V
4.7µF
1000pF
B
P
VCO
MURATA
MQE001-902
M
C
f
OUT
902MHz
100k
V
C
AMPLITUDE
10dB/DIV
U
Open-Loop Close-In Phase Noise
CENTER = 902MHz
SPAN = 100kHz
SWP = 10 sec
RES BW = 1kHz
VBW = 30Hz
REF = 0dBm
1682 TA02
U
U
1
LTC1682/LTC1682-3.3/LTC1682-5
ABSOLUTE
MAXIMUM
RATINGS
V
IN
to Ground ..............................................– 0.3V to 5V
V
OUT
Voltage ................................................– 0.3V to 6V
CPO to Ground ........................................................ 10V
SHDN, FILT/FB Voltage to
Ground ..................................... – 0.3V to (V
IN
+ 0.3V)
V
OUT
Short-Circuit Duration ............................ Indefinite
I
OUT
...................................................................... 90mA
PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
TOP VIEW
V
OUT
SHDN
FILT/FB*
GND
1
2
3
4
8
7
6
5
CPO
C
+
V
IN
C
–
MS8 PACKAGE
8-LEAD PLASTIC MSOP
*PIN3 = FILT FOR LTC1682-3.3/LTC1682-5
= FB FOR LTC1682
T
JMAX
= 125°C,
θ
JA
= 140°C/ W
LTC1682CMS8
LTC1682CMS8-3.3
LTC1682CMS8-5
LTC1682IMS8
LTC1682IMS8-3.3
LTC1682IMS8-5
MS8 PART MARKING
LTER
LTGT
LTGV
LTHM
LTGU
LTGW
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
V
IN
Operating Voltage
CONDITIONS
LTC1682
LTC1682-3.3
LTC1682-5
SHDN = 0V
The
q
denotes specifications that apply over the full operating temperature
range, otherwise specifications are T
A
= 25°C. SHDN = V
IN
= 3V; C1 = 0.22µF; C2, C3, C4 = 4.7µF, unless otherwise noted.
MIN
q
q
q
q
TM
I
VIN
Shutdown Current
I
VIN
Operating Current
I
OUT
= 0mA, Burst Mode Operation
0°C to 70°C
– 40°C to 85°C
LTC1682, FB = 1.235V
LTC1682
LTC1682-3.3, I
OUT
= 1mA
LTC1682-5, I
OUT
= 1mA
I
OUT
> 200µA, V
IN
= 1.8V to 4.4V
FB Input Current
FB Voltage
Regulated Output Voltage
V
OUT
Temperature Coefficient
Charge Pump Oscillator Frequency
Burst Mode is a trademark of Linear Technology Corporation.
2
U
U
W
W W
U
W
(Note 1)
Operating Temperature Range
Commercial ............................................ 0°C to 70°C
Extended Commercial (Note 2) ........... – 40°C to 85°C
Industrial ........................................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Maximum Junction Temperature .......................... 125°C
ORDER PART
NUMBER
TOP VIEW
V
OUT
1
SHDN 2
FILT/FB* 3
GND 4
8
7
6
5
CPO
C
+
V
IN
C
–
S8 PACKAGE
8-LEAD PLASTIC SO
*PIN3 = FILT FOR LTC1682-3.3/LTC1682-5
= FB FOR LTC1682
T
JMAX
= 125°C,
θ
JA
= 120°C/ W
LTC1682CS8
LTC1682CS8-3.3
LTC1682CS8-5
LTC1682IS8
LTC1682IS8-3.3
LTC1682IS8-5
S8 PART MARKING
1682
168233
16825
1682I
1682I33
1682I5
TYP
MAX
4.4
4.4
4.4
UNITS
V
V
V
µA
µA
µA
nA
V
V
V
ppm
kHz
1.8
2
2.7
1
150
150
– 50
1.210
3.23
4.9
480
1.235
3.30
5.0
±50
550
5
250
300
50
1.260
3.37
5.1
620
q
q
q
q
q
q
q
LTC1682/LTC1682-3.3/LTC1682-5
ELECTRICAL CHARACTERISTICS
PARAMETER
CPO (Charge Pump Output)
Output Resistance
V
OUT
Dropout Voltage (Note 3)
CONDITIONS
V
IN
= 1.8V, I
OUT
= 10mA
V
IN
= 3V, I
OUT
= 10mA
V
IN
= 4.4V, I
OUT
= 10mA
The
q
denotes specifications that apply over the full operating temperature
range, otherwise specifications are T
A
= 25°C. SHDN = V
IN
= 3V; C1 = 0.22µF; C2, C3, C4 = 4.7µF, unless otherwise noted.
MIN
q
q
q
q
q
q
TYP
18
13
11
100
75
50
2
88
800
58
500
64
600
MAX
30
20
17
160
120
90
UNITS
Ω
Ω
Ω
mV
mV
mV
ms
µV
RMS
µV
P-P
µV
RMS
µV
P-P
µV
RMS
µV
P-P
LTC1682, I
OUT
= 10mA, V
OUT
= 2.57V (Note 5)
LTC1682/LTC1682-3.3, I
OUT
= 10mA, V
OUT
= 3.3V
LTC1682/LTC1682-5, I
OUT
= 10mA, V
OUT
= 5V
I
OUT
= 10mA
LTC1682
LTC1682-3.3
LTC1682-5
I
OUT
= 10mA, 10Hz
≤
f
≤
100kHz, V
OUT
= 5V
I
OUT
= 10mA, 10Hz
≤
f
≤
2.5MHz, V
OUT
= 5V
I
OUT
= 10mA, 10Hz
≤
f
≤
100kHz, C
FILT
= 1nF
I
OUT
= 10mA, 10Hz
≤
f
≤
2.5MHz, C
FILT
= 1nF
I
OUT
= 10mA, 10Hz
≤
f
≤
100kHz, C
FILT
= 1nF
I
OUT
= 10mA, 10Hz
≤
f
≤
2.5MHz, C
FILT
= 1nF
V
OUT
Enable Time
V
OUT
Output Noise Voltage
V
OUT
Line Regulation
V
OUT
Load Regulation
V
OUT
Shutdown Resistance
SHDN Input Threshold
SHDN Input Current
V
IN
= 3V to 4V, I
OUT
= 0mA (Note 6)
I
OUT
= 1mA to 10mA
I
OUT
= 1mA to 50mA (Note 4)
SHDN = 0V, Resistance Measured to Ground, V
IN
= 1.8V
SHDN = 0V, Resistance Measured to Ground, V
IN
= 4.4V
V
IN
= 1.8V to 4.4V
SHDN = V
IN
SHDN = 0V
q
q
q
q
q
q
q
5
3
10
150
50
0.4
–1
–1
1
20
10
350
150
1.6
1
1
mV
mV
mV
Ω
Ω
V
µA
µA
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC1682C is guaranteed to meet specified performance from
0°C to 70°C and is designed, characterized and expected to meet these
extended temperature limits, but is not tested at – 40°C and 85°C. The
LTC1682I is guaranteed to meet the extended temperature limits.
Note 3:
Dropout voltage is the minimum input/output voltage required to
maintain regulation at the specified output current. In dropout the output
voltage will be equal to: V
CPO
– V
DROPOUT
(see Figure 4).
Note 4:
Operating conditions are limited by maximum junction
temperature. The regulated output specification will not apply for all
possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range may be
limited. When operating at maximum output current, the input voltage
range may be limited.
Note 5:
Limited by the LDO disable switch point of 1.45V
IN
.
Note 6:
The LTC1682 is set to 5V. The feedback current is 25µA.
3
LTC1682/LTC1682-3.3/LTC1682-5
TYPICAL PERFOR A CE CHARACTERISTICS
CPO Output Resistance vs V
IN
35
30
25
T
A
= 25°C
C1 = 0.22µF
I
OUT
= 10mA
9
T
A
= 25°C
8
7
V
CPO
(V)
∆V
OUT
(mV)
R
CPO
(Ω)
20
15
4
10
3
5
V
CPO
= 1.45(V
IN
)
I
OUT
(mA)
1.5
2.0
2.5
3.0
V
IN
(V)
3.5
LTC1682-5 Output Noise
(BW = 10Hz to 2.5MHz)
SHDN (V)
2
0
4
SHDN (V)
V
OUT
200µV/DIV
V
OUT
(V)
2
1
V
OUT
(V)
100µs/DIV
C
CPO
= C
OUT
= 4.7µF
V
OUT
= 5V
T
A
= 25°C
I
OUT
= 10mA
C
FILT
= 1nF
V
IN
= 3V
Oscillator Frequency vs
Temperature
565
V
IN
= 3V
OSCILLATION FREQUENCY (kHz)
220
200
560
OPERATING CURRENT (µA)
555
550
545
540
535
530
–50 –25
4
U W
4.0
Min and Max V
CPO
vs V
IN
10
5
0
–5
–10
(B)
15
10
5
0
4.5
1682 G01
V
OUT
Transient Response
V
CPO
= 2(V
IN
)
(A)
6
5
T
A
= 25°C
V
IN
= 3V
V
OUT
= 4V
C
OUT
= 10µF
1.5
2.0
2.5
3.0
V
IN
(V)
3.5
4.0
4.5
0
50
100
150
200
TIME (µs)
250
300
1682 G02
(A) THE MAXIMUM GENERATED NO LOAD
CPO VOLTAGE
(B) THE MINIMUM ALLOWABLE CPO VOLTAGE,
AT FULL LOAD, TO ENSURE THAT THE LDO
IS NOT DISABLED
1682 G02
Shutdown to Enable Timing
2
0
4
T
A
= 25°C
V
IN
= 3V
V
OUT
= 4V
I
OUT
= 10mA
C
CPO
= C
OUT
= 10µF
3
2
1
0
200µs/DIV
1682 G05
Enable to Shutdown Timing
3
1682 G04
0
NO LOAD
T
A
= 25°C
V
IN
= 3V
V
OUT
= 4V
C
OUT
= 10µF
1ms/DIV
1682 G06
Operating Current vs V
IN
(No Load)
T
A
= 25°C
180
160
140
LTC1682-3.3
LTC1682-5
LTC1682
120
100
80
60
1.5
2.0
2.5
3.0
V
IN
(V)
3.5
4.0
4.5
1682 G08
50
25
75
0
TEMPERATURE (°C)
100
125
1682 G07
LTC1682/LTC1682-3.3/LTC1682-5
TYPICAL PERFOR A CE CHARACTERISTICS
V
OUT
Voltage vs Temperature
5.030
V
IN
= 3V
5.020
I
OUT
= 10mA
5.010
5.000
LTC1682-5
4.990
3.340
3.330
3.320
LTC1682-3.3
3.310
3.300
3.290
1.240
1.238
LTC1682
1.236
1.234
75
0
50
–50 –25
25
TEMPERATURE (°C)
5.000
4.999
4.998
4.997
4.996
4.995
4.994
4.993
3.300
3.299
3.298
3.297
3.296
3.295
3.294
0
5
V
OUT
VOLTAGE (V)
V
OUT
VOLTAGE (V)
PIN FUNCTIONS
V
OUT
(Pin 1):
Low Noise Regulated Output Voltage. V
OUT
should be bypassed with a
≥
2µF low ESR capacitor as
close to the pin as possible for best performance. The V
OUT
range is 2.5V to 5.5V.
SHDN (Pin 2):
Shutdown Input. A logic low on the SHDN
pin puts the part in shutdown mode. A logic high enables
the part. To continuously enable the part connect SHDN to
V
IN
. When the part is in shutdown, V
OUT
will be connected
to ground via a 100Ω switch and CPO will be high
impedance disconnected from V
IN
.
FB (Pin 3) (LTC1682):
The voltage on this pin is compared
to the internal reference voltage (1.235V) by the error
amplifier to keep the output in regulation. An external
resistor divider is required between V
OUT
and FB to adjust
the output voltage.
FILT (Pin 3) (LTC1682-3.3/LTC1682-5):
This pin is used
to filter the internal voltage reference. Typically a 1nF
capacitor is connected from FILT to ground.
GND (Pin 4):
System Ground.
C
–
(Pin 5):
Flying Capacitor Negative Input.
V
IN
(Pin 6):
Input Voltage, 1.8V to 4.4V. V
IN
should be
bypassed with a
≥
2µF low ESR capacitor as close to the
pin as possible for best performance. A minimum capaci-
tance value of 0.1µF is required.
C
+
(Pin 7):
Flying Capacitor Positive Input.
CPO (Pin 8):
Unregulated Charge Pump Output Voltage.
Approximately 1.95(V
IN
) at low loads. Bypass with a
≥
2µF
low ESR capacitor. If a minimum V
OUT
enable time is
required, the CPO capacitor should be 2× the V
OUT
capacitor.
U W
V
OUT
Voltage vs Output Current
V
IN
= 3.3V
T
A
= 25°C
LTC1682-5
LTC1682-3.3
100
125
10 15 20 25 30 35 40 45 50
OUTPUT CURRENT (mA)
1682 G10
1682 G09
U
U
U
5
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