Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Switched-capacitor voltage converter SOIC 8

LTC1682/LTC1682-3.3/LTC1682-5

Doubler Charge Pumps with

Low Noise Linear Regulator

■

Low Output Noise: 60

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

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

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.

Open-Loop Close-In Phase Noise

CENTER = 902MHz RES BW = 1kHz

SPAN = 100kHz VBW = 30Hz

SWP = 10 sec REF = 0dBm

1682 TA02

4.2V VCO Power Supply, V

= 2.5V to 4.4V

■

VCO Power Supplies in Cellular Phones

■

2-Way Pagers

■

Wireless PCMCIA Cards

■

Portable Medical Instruments

■

Low Power Data Acquisition

■

Remote Transmitters

AMPLITUDE

10dB/DIV

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

36k

SHUTDOWN

15k

100k

4.7µF

0.22µF

2.5V TO

4.4V

4.7µF

4.2V

OUT

SHDN

GND

CPO

–

1682 TA01

LTC1682

VCO

MURATA

MQE001-902

1µF

4.7µF

1000pF

4.7µF

OUT

902MHz

Summary of content (12 pages)

PAGE 1
LTC1682/LTC1682-3.3/LTC1682-5 Doubler Charge Pumps with Low Noise Linear Regulator U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Low Output Noise: 60µVRMS (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.
PAGE 2
LTC1682/LTC1682-3.3/LTC1682-5 W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) VIN to Ground ..............................................– 0.3V to 5V VOUT Voltage ................................................– 0.3V to 6V CPO to Ground ........................................................ 10V SHDN, FILT/FB Voltage to Ground ..................................... – 0.3V to (VIN + 0.3V) VOUT Short-Circuit Duration ............................ Indefinite IOUT ..............................................
PAGE 3
LTC1682/LTC1682-3.3/LTC1682-5 ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25°C. SHDN = VIN = 3V; C1 = 0.22µF; C2, C3, C4 = 4.7µF, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS CPO (Charge Pump Output) Output Resistance VIN = 1.8V, IOUT = 10mA VIN = 3V, IOUT = 10mA VIN = 4.4V, IOUT = 10mA ● ● ● 18 13 11 30 20 17 Ω Ω Ω VOUT Dropout Voltage (Note 3) LTC1682, IOUT = 10mA, VOUT = 2.
PAGE 4
LTC1682/LTC1682-3.3/LTC1682-5 U W TYPICAL PERFOR A CE CHARACTERISTICS 9 TA = 25°C C1 = 0.22µF IOUT = 10mA 10 TA = 25°C 8 VCPO = 2(VIN) 7 VCPO (V) 25 20 5 ∆VOUT (mV) 30 RCPO (Ω) VOUT Transient Response Min and Max VCPO vs VIN CPO Output Resistance vs VIN 35 0 (A) 6 TA = 25°C VIN = 3V VOUT = 4V COUT = 10µF –5 –10 (B) 5 15 IOUT (mA) 15 VCPO = 1.45(VIN) 4 10 10 5 3 0 2.5 2.0 3.0 VIN (V) 3.5 4.0 1.5 4.5 1682 G01 2.0 2.5 3.0 VIN (V) 4.0 3.5 0 4.
PAGE 5
LTC1682/LTC1682-3.3/LTC1682-5 U W TYPICAL PERFOR A CE CHARACTERISTICS VOUT Voltage vs Output Current VOUT VOLTAGE (V) VOUT VOLTAGE (V) VOUT Voltage vs Temperature 5.030 VIN = 3V 5.020 IOUT = 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) 100 125 5.000 4.999 4.998 4.997 4.996 4.995 4.994 4.993 VIN = 3.3V TA = 25°C LTC1682-5 3.300 3.299 3.298 3.297 3.296 3.295 3.294 LTC1682-3.
PAGE 6
LTC1682/LTC1682-3.3/LTC1682-5 W BLOCK DIAGRA SM C1 0.22µF C+ 5 C– CHARGE PUMP AND SLEW CONTROL C4 4.7µF 8 ENB CLK1 CPO C3 4.7µF 275k – 6 VIN 7 + 38k SHDN 2 + POWERON RESET 550kHz OSCILLATOR REG B – SD 328k REGEN ENB 1:100 – + VIN 1 VOUT LDO C2 4.7µF REGEN SD VREF = 1.235V 100Ω 1µA/2µA 3 FB 4 GND R1 R2 1682 F01 Figure 1.
PAGE 7
LTC1682/LTC1682-3.3/LTC1682-5 W BLOCK DIAGRA SM C1 0.22µF C+ 5 C– CHARGE PUMP AND SLEW CONTROL C4 4.7µF 8 CPO C3 4.7µF 275k – 6 VIN 7 ENB CLK1 + 38k SHDN 2 + POWERON RESET 550kHz OSCILLATOR REG B – SD FILT 1nF 328k REGEN ENB – 3 200k 1:100 + VIN 1 VOUT LDO C2 4.7µF REGEN SD VREF = 1.235V RA 120k/65.5k RB 200k 100Ω 1µA/2µA 4 1682 F02 GND Figure 2. LTC1682-3.
PAGE 8
LTC1682/LTC1682-3.3/LTC1682-5 U W U U APPLICATIONS INFORMATION Operation The LDO is used to filter the ripple on CPO and to set an output voltage independent of CPO. VOUT is set by an external or internal resistor divider. The LDO requires a capacitor on VOUT for stability and improved load transient response. A low ESR capacitor of ≥ 2µF should be used. The LTC1682 uses a switched-capacitor charge pump to generate a CPO voltage of approximately 2(VIN).
PAGE 9
LTC1682/LTC1682-3.3/LTC1682-5 U W U U APPLICATIONS INFORMATION The following formula can be used to find the maximum output voltage that may be programmed for a given minimum input voltage and output current load: VOUT(MAX) = (2)(VIN(MIN)) – (IOUT)(RCPO) – VDROPOUT with the condition that (IOUT)(RCPO) < 0.55VIN. Example: VIN(MIN) = 3V IOUT = 10mA RCPO(MAX) = 20Ω Max unloaded CPO voltage = 6V Loaded CPO voltage = 6V – (10mA)(20Ω) = 5.8V VDROPOUT(MAX) = 0.08V VOUT(MAX) = (6V) – (0.2V) – (0.08V) = 5.
PAGE 10
LTC1682/LTC1682-3.3/LTC1682-5 U U W U APPLICATIONS INFORMATION Power-On Reset General Layout Considerations Upon initial power-up, a power-on reset circuit ensures that the internal functions are correctly initialized when power is applied. Once VIN reaches approximately 1V, the power-on reset circuit will enable the part as long as the SHDN pin is held high. Due to the high switching frequency and high transient currents produced by the device, careful board layout is a must.
PAGE 11
LTC1682/LTC1682-3.3/LTC1682-5 U TYPICAL APPLICATION 3.3V to Low Noise 3.3V Converter SHUTDOWN 8 C3 4.7µF VIN 3.3V 7 6 C4 4.7µF C1 0.22µF 5 CPO VOUT C+ SHDN LTC1682-3.3 VIN C– FILT GND 1 C2 4.7µF 2 3.3V VRIPPLE = 500µVP-P 3 CFILT 1nF 4 1682 TA03 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.118 ± 0.004* (3.00 ± 0.102) 0.040 ± 0.006 (1.02 ± 0.15) 0.007 (0.18) 0.034 ± 0.004 (0.86 ± 0.
PAGE 12
LTC1682/LTC1682-3.3/LTC1682-5 U TYPICAL APPLICATION Wide Input Range VCO Supply (VIN > 4.4V) VIN 3V TO 6V Q1 FMMT3904 R1 470Ω 8 C3 4.7µF D1 1N4148 3V (REQUIRED FOR START-UP) C4 4.7µF 7 6 C1 0.22µF 5 CPO C+ VOUT SHDN LTC1682-5 VIN C– FILT GND 5V LOW NOISE 1 2 SHUTDOWN C2 4.