Datasheet

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LTC3200/LTC3200-5

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

The LTC

3200/LTC3200-5 are low noise, constant fre-

quency switched capacitor voltage doublers. They pro-

duce a regulated output voltage from a 2.7V to 4.5V input

with up to 100mA of output current. Low external parts

count (one flying capacitor and two small bypass capaci-

tors at V

and V

OUT

) make the LTC3200/LTC3200-5

ideally suited for small, battery-powered applications.

A new charge-pump architecture maintains constant

switching frequency to zero load and reduces both output

and input ripple. The LTC3200/LTC3200-5 have thermal

shutdown capability and can survive a continuous short-

circuit from V

OUT

to GND. Built-in soft-start circuitry

prevents excessive inrush current during start-up.

High switching frequency enables the use of small ceramic

capacitors. A low current shutdown feature disconnects

the load from V

and reduces quiescent current to <1µA.

The LTC3200 is available in an 8-pin MSOP package and

the LTC3200-5 is available in a 6-pin ThinSOT.

■

White LED Backlighting

■

Li-Ion Battery Backup Supplies

■

Local 3V to 5V Conversion

■

Smart Card Readers

■

PCMCIA Local 5V Supplies

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

Low Noise Constant Frequency Operation

■

Output Current: 100mA

■

Available in 8-Pin MSOP (LTC3200) and Low

Profile (1mm) 6-Pin ThinSOT

(LTC3200-5)

Packages

■

2MHz Switching Frequency

■

Fixed 5V ± 4% Output (LTC3200-5) or ADJ

■

Range: 2.7V to 4.5V

■

Automatic Soft-Start Reduces Inrush Current

■

No Inductors

■

<1µA in Shutdown

Low Noise, Regulated

Charge Pump DC/DC Converters

Regulated 5V Output from a 2.7V to 4.5V Input

Output Ripple Voltage vs Load Current

OUTPUT CURRENT (mA)

OUTPUT RIPPLE (mV

P-P

)

100

3200 TA02

OUT

= 2.2µF

OUT

= 1µF

= 3V

FLY

= 1µF

= 25°C

LTC3200-5

OUT

3200-5 TA01

1µF

GND

–

SHDN

OFF

2.7V TO 4.5V

OUT

5V ±4%

OUT

UP TO 40mA, V

≥ 2.7V

OUT

UP TO 100mA, V

≥ 3.1V

ALL CAPACITORS = MURATA GRM 39X5R105K6.3AJ

OR TAIYO YUDEN JMK107BJ105MA

ThinSOT is a trademark of Linear Technology Corporation.

Summary of content (12 pages)

PAGE 1
LTC3200/LTC3200-5 Low Noise, Regulated Charge Pump DC/DC Converters U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC®3200/LTC3200-5 are low noise, constant frequency switched capacitor voltage doublers. They produce a regulated output voltage from a 2.7V to 4.5V input with up to 100mA of output current. Low external parts count (one flying capacitor and two small bypass capacitors at VIN and VOUT) make the LTC3200/LTC3200-5 ideally suited for small, battery-powered applications.
PAGE 2
LTC3200/LTC3200-5 W W U W ABSOLUTE AXI U RATI GS (Note 1) VIN to GND ...................................................– 0.3V to 6V VOUT to GND .............................................– 0.3V to 5.5V VFB, SHDN to GND ........................ – 0.3V to (VIN + 0.3V) IOUT (Note 2) ....................................................... 150mA VOUT Short-Circuit Duration ............................. Indefinite Operating Temperature Range (Note 3) .. – 40°C to 85°C Storage Temperature Range ........
PAGE 3
LTC3200/LTC3200-5 U W TYPICAL PERFOR A CE CHARACTERISTICS Output Voltage vs Supply Voltage OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) TA = 25°C 5.00 CIN = COUT = CFLY = 1µF VSHDN = VIN CIN = COUT = CFLY = 1µF TA = 25°C TA = 85°C 5.05 6 5.2 CIN = COUT = CFLY = 1µF IOUT = 20mA 5.10 No Load Supply Current vs Supply Voltage Output Voltage vs Load Current TA = – 40°C 4.95 SUPPLY CURRENT (mA) 5.15 (LTC3200-5) 5.1 5.0 VIN = 3.2V VIN = 2.7V VIN = 3V 4.9 TA = 25°C 5 TA = 85°C 4 TA = – 40°C 4.
PAGE 4
LTC3200/LTC3200-5 U W TYPICAL PERFOR A CE CHARACTERISTICS VOUT Soft-Start Ramp (LTC3200-5) TA = 25°C Load Transient Response Output Ripple VSHDN 2V/DIV VOUT (AC COUPLED) 20mV/DIV COUT = 1µF VOUT 1V/DIV COUT = 3.3µF IL 10mA TO 90mA 50mA/DIV VOUT (AC COUPLED) 50mV/DIV COUT = 10µF VIN = 3V 200µs/DIV 32005 G08 U U U PIN FUNCTIONS VIN = 3.3V IL = 100mA 32005 G09 VIN = 3.3V COUT = 1µF 10µs/DIV 32005 G10 LTC3200/LTC3200-5 C + (Pins 1/6): Flying Capacitor Positive Terminal.
PAGE 5
LTC3200/LTC3200-5 W W SI PLIFIED BLOCK DIAGRA S LTC3200 SOFT-START AND SWITCH CONTROL VOUT 8 FB 7 6 SHDN 1 C+ 3 C– 2MHz OSCILLATOR – + CHARGE PUMP VIN 2 5 4 SGND PGND 3200 BD LTC3200-5 SOFT-START AND SWITCH CONTROL VOUT 3 SHDN 6 C+ 4 C– 1 2MHz OSCILLATOR – + CHARGE PUMP VIN 5 2 3200-5 BD GND 5
PAGE 6
LTC3200/LTC3200-5 U OPERATIO Operation (Refer to Simplified Block Diagrams) The LTC3200/LTC3200-5 use a switched capacitor charge pump to boost VIN to a regulated output voltage. Regulation is achieved by sensing the output voltage through an internal resistor divider (LTC3200-5) and modulating the charge pump output current based on the error signal. A 2-phase nonoverlapping clock activates the charge pump switches. The flying capacitor is charged from VIN on the first phase of the clock.
PAGE 7
LTC3200/LTC3200-5 U OPERATIO Maximum Available Output Current For the adjustable LTC3200, the maximum available output current and voltage can be calculated from the effective open-loop output resistance, ROL, and effective output voltage, 2VIN(MIN). ROL + – + 2VIN IOUT VRIPPLEP − P ≅ 32005 F02 Figure 2. Equivalent Open-Loop Circuit From Figure 2 the available current is given by: 2VIN – VOUT ROL Typical ROL values as a function of temperature are shown in Figure 3.
PAGE 8
LTC3200/LTC3200-5 U OPERATIO LTC3200/LTC3200-5 will be relatively constant while the charge pump is on either the input charging phase or the output charging phase but will drop to zero during the clock nonoverlap times. Since the nonoverlap time is small (~25ns), these missing “notches” will result in only a small perturbation on the input power supply line. Note that a higher ESR capacitor such as tantalum will have higher input noise due to the input current change times the ESR.
PAGE 9
LTC3200/LTC3200-5 U OPERATIO Power Efficiency Layout Considerations The power efficiency (η) of the LTC3200/LTC3200-5 is similar to that of a linear regulator with an effective input voltage of twice the actual input voltage. This occurs because the input current for a voltage doubling charge pump is approximately twice the output current.
PAGE 10
LTC3200/LTC3200-5 U OPERATIO The power dissipated in the LTC3200/LTC3200-5 should always fall under the line shown for a given ambient temperature.
PAGE 11
LTC3200/LTC3200-5 U PACKAGE DESCRIPTIO S6 Package 6-Lead Plastic ThinSOT-23 (LTC DWG # 05-08-1634) 2.80 – 3.10 (.110 – .118) (NOTE 3) SOT-23 (Original) SOT-23 (ThinSOT) A .90 – 1.45 (.035 – .057) 1.00 MAX (.039 MAX) A1 .00 – 0.15 (.00 – .006) .01 – .10 (.0004 – .004) A2 .90 – 1.30 (.035 – .051) .80 – .90 (.031 – .035) L .35 – .55 (.014 – .021) .30 – .50 REF (.012 – .019 REF) 2.60 – 3.00 (.102 – .118) 1.50 – 1.75 (.059 – .069) (NOTE 3) PIN ONE ID .95 (.037) REF .25 – .50 (.010 – .
PAGE 12
LTC3200/LTC3200-5 U TYPICAL APPLICATIO S White or Blue LED Driver with LED Current Control 1µF 1 2 3V TO 4.4V Li-Ion BATTERY C 3 + C– VOUT VIN 1µF 1µF LTC3200 FB ON OFF 6 SGND SHDN UP TO 6 LEDS 8 PGND 7 5 82Ω 82Ω 82Ω 82Ω 82Ω 82Ω 4 32005 TA04 (APPLY PWM WAVEFORM FOR ADJUSTABLE BRIGHTNESS CONTROL) VSHDN t Lithium-Ion Battery to 5V White or Blue LED Driver 1µF 4 5 3V TO 4.