PS0100-2.8 - Power IC Ltd.

PS0100

July 2007 www.picsemi.com

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600mA Synchronous Boost

Converter with Output Disconnect

DESCRIPTION

FEATURES The PS0100 is a synchronous, step-up DC/DC

converter delivering high efficiency in a SOT-26

package. The device has an internal NMOS switch

and PMOS synchronous rectifier and has the

capacity of supplying 3.3V at 100mA from a single

AA cell input.

 Up to 92% efficiency

 Low start-up voltage 0.8V

 Internal synchronous rectifier

 Up to 2MHz switching allows for tiny

external components

 0.5V to 4.4V input range

 2.5V to 5.0V output range (Note 3) High frequency switching (up to 2MHz) minimizes

the board area by allowing the use of tiny, low

profile inductors and ceramic capacitors.

 Fully discharged shutdown output voltage

 Logic controlled shutdown (<1µA)

 Low 250µA operating supply current

(measured at VOUT) The PS0100 provides automatic pulse skipping at

light loads, thus reducing the supply current for

extended battery life. At shutdown, the PS0100

fully discharges the output to ground and draws no

supply current.

 Pulse skipping at light load for extended

battery life

 Generates 3.3V at 100mA from single AA

cell

 Stable with ceramic output capacitor The PS0100 is available in small SOT-26 package

with both fixed and adjustable output voltage

versions.

 Low profile 6-Leads SOT-26 package

APPLICATIONS

 MP3 / MP4 players

 PDAs and organizers

 Digital cameras

 Wireless mice/ keyboards

 Portable medical equipment

 Cordless phones

 Wireless Headsets

TYPICAL APPLICATION CIRCUIT

PS0100

PIN CONFIGURATION

PIN DESIGNATOR

Name Pin Type Function

SW 1 Switch Connects inductor between SW and VIN

GND 2 Ground Ground pin

FB 3 Feedback Adjustable feedback input, connects to resistor voltage divider

SHUTB 4 Shutdown input SHUTB = High: normal operation (Supports both TTL and CMOS logic)

VOUT 5 Analog output Boost regulator output

VIN 6 Battery input Boost regulator input

ORDERING INFORMATION

Part Number Voltage Junction Temperature Range Package

PS0100A Adj. -40°C to 85°C SOT-26

PS0100 – 2.5 2.5 -40°C to 85°C SOT-26

PS0100 – 2.8 2.8 -40°C to 85°C SOT-26

PS0100 – 3.0 3.0 -40°C to 85°C SOT-26

PS0100 – 3.3 3.3 -40°C to 85°C SOT-26

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PS0100

BLOCK DIAGRAM

Dischar

g

e Switch Body Mana

g

e Switch

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Thermal

Sensor Gate Control

Logic

Bias

Select

Start-up

Oscillator

Shut-Down

Circuitry

REFERENCE

Fixed TON

Time Control

Logic

Minimum

TOFF

Under Voltage

Lockout

Zero-Current

Ref

Pro

g

ram Volta

g

e

Over-Current

Limiter

+ -

+

-

+

_

Bias to all

Circuitry

Shut Down

SW

VIN

GND

UVLOB

REF

Current Sense

Amplifier

Zero Crossin

g

Comparator

SHUTB

VOUT

FB

PS0100

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

VDC Supply Voltage at Pin 6 -0.3 to 6.0 V

IN

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SW Voltage - DC -0.3 to 6.0 V VSW SW Voltage–Pulsed (<100nS) -0.3 to 7.0 V

VSHUTB Voltage -0.3 to 6.0 V

SHUTB

VFB Voltage -0.3 to 6.0 V

FB

VOutput Voltage -0.3 to 6.0 V

OUT

ISW, I I Switch Current 0 to 1A A

OUT, GND

TStorage Temperature Range -65 to +125 °C

STG

RThermal Resistance, Junction-To-Air N/A °C/W

θJA

TOperating Temperature Range (Note 4) -40 to +85 °C

A, MAX

TLead Temperature (Soldering, 10sec ) 260 °C

L

ESD ESD Capability, HBM model 2.0 KV

ELECTRICAL CHARACTERISTICS

(All specifications are at T = 25°C, V = 1.5V, V = 3.3V, V = 1.5V, unless otherwise specified.)

AIN OUT SHUTB

Parameter Conditions Min Typ Max Unit

Minimum Start-Up Voltage No load 0.8 0.95 V

Note 1 0.5 V

Minimum Operating Voltage Note 2 4.4 V

Maximum Input Operating

Voltage Note 3 2.5 5.0 V

Output Voltage Adjust Range = -40°C to 85°C (Note 4) 0.97 1.0 1.03 V

T

Feedback Voltage A = 1.2V 1 nA

V

Feedback Input Current FB

Load Regulation ILOAD = 10mA to 100mA 2.2 %

= 1.2V, measured at VOUT 250 420 µA

V

Quiescent Current FB

(No-Switching) = 0V, V

Quiescent Current (Shut-down) VSHUTB OUT = 0V, including

switch leakage 0.01 1 µA

= 3.3V 0.45 Ω

V

NMOS Switch On Resistance OUT

= 3.3V 0.6 Ω

V

PMOS Switch On Resistance OUT

600 mA

NMOS Current Limit 50 mA

PMOS Turn-Off Current 100 nS

Current Limit Delay to Output 0.13 µS

Minimum Off-Time = 0.5V 0.6 0.95 1.4 µS

V

Maximum On-Time IN

= 0.95V, V = 0.5V,

V4 7.3

Maximum On-Time to Minimum

Off-Time Ratio FB IN

T = -40°C to 85°C (Note 4)

A

PS0100

ELECTRICAL CHARACTERISTICS (continued)

(All specifications are at T = 25°C, V = 1.5V, V = 3.3V, V = 1.5V, unless otherwise specified.)

AIN OUT SHUTB

Parameter Conditions Min Type Max Unit

0.95 V

SHUTB Input High 0.35 V

SHUTB Input Low 100 nA

SHUTB Input Current 650 KHz

Frequency at Start-Up

Thermal Shutdown 15°C Hysteresis 145 °C

Note 1: Minimum operating input voltage is fixed by the battery’s ability to provide necessary power at that

(terminal) voltage. Below this voltage, the battery fails to deliver required power as it enters into deeply

discharged state. This voltage can be lower if the required duty cycle is less.

Note 2: When the input voltage is greater than the output voltage regulation point, the part operates in track

mode (see Track Mode).

Note 3: For applications where V > 4.3V, an external Schottky diode is recommended.

OUT

Note 4: Limits are 100% production tested at TA=25°C. Specifications over the -40°C to +85°C operating

temperature range are assured by design.

July 2007 www.picsemi.com

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PS0100

TYPICAL OPERATING CHARACTERISTICS

(All specifications are at T =+25°C, V = 1.5V, circuit of typical application circuit, unless otherwise specified.)

AIN

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PS0100

TYPICAL OPERATING CHARACTERISTICS (continued)

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PS0100

TYPICAL OPERATING CHARACTERISTICS (continued)

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PS0100

TYPICAL OPERATING CHARACTERISTICS (continued)

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PS0100

OPERATION

The PS0100 is a compact, high-efficiency, synchronous

boost converter in a SOT-26 package designed for space-

restricted applications. The part is available with

adjustable output voltages ranging from 2.5V to 5.0V. It

is able to start up with input voltages as low as 0.8V and

operate with input voltages down to 0.5V. With its

internal synchronous rectifier and low on-resistance of

the internal NMOS switch, the device maintains high

efficiency over a wide range of load current. As shown in

the Block Diagram, the PS0100 consists of accurate band

gap core, error amplifier, start-up oscillator and control

logic unit along with PMOS and NMOS switches. With

current mode PWM control, the PS0100 has ultra-fast line

and improved load regulation. Moreover, the PS0100

provides real shutdown circuitry which disconnects the

output from the input during shutdown and results in the

discharge of the output to ground.

conductive path through the body of the PMOS, the

output is allowed to go to zero during shutdown, drawing

zero current from the input.

Output Voltage Selection

The PS0100 features a user-adjustable output through an

external feedback network. A voltage divider from VOUT

to ground programs the output voltage via FB from 2.5V

to 5V using the following equation:

= V

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Start-Up Mode

The PS0100 starts up typically at 0.8V. When it is turned

on, the device gets its start up bias from VIN. A start-up

oscillator, which runs typically at 650 KHz, takes the

output voltage high enough so that V

OUT exceeds VIN.

Once VOUT exceeds VIN, the internal bias switches from

VIN to VOUT by an internal bias-select circuit. Thus, once

started (i.e. VOUT exceeds VIN), the internal circuit bias is

completely independent of VIN. The start-up oscillator

runs at 66% duty cycle at around 650KHz. Once VOUT

exceeds VIN (typically 1.9V), the start-up oscillator is

disabled and the normal fixed TON PWM operation takes

over.

Internal PMOS and NMOS Switches

The PS0100 features a 0.45Ω NMOS switch and a 0.6Ω

PMOS switch. In normal operation, these switches are

alternatively turned on and thus initiate the charging of

the inductor from VIN and then discharging of it to the

output capacitor and the load. However, between the

event of one switch turning off and the other turning on ,

a dead time is provided to avoid a huge in-rush current

from the output to ground via switches. During the dead

time, both switches remain off and the inductor

discharges via the body diode of the PMOS switch to the

output.

True Shutdown Mode

The PS0100 is designed to allow for true shutdown by

managing the body diode of the PMOS switch. As the

PMOS switch is turned off and there is no

VOUT REF × [1 + (R1/R2)]

where, VREF = 1.0V

Thermal Overload Protection

Thermal overload protection limits the total power

dissipation in the PS0100. When the junction temperature

exceeds TJ = +145°C, the thermal sensor signals the

shutdown logic and turns off most of the internal

circuitry. The thermal sensor turns the internal circuitry

on again after the IC’s junction temperature drops by

15°C.

Thermal overload protection is designed to protect the

PS0100 in the event of a fault condition. For continuous

operation, do not exceed the absolute maximum junction

temperature rating of TJ = +125°C.

Current Limit and Short Circuit Protection

The PS0100 includes a current limiter that monitors the

peak inductor current through the NMOS switch and

turns the NMOS switch off when the inductor peak

current exceeds 850mA. Because of its true shutdown

feature, the IC is allowed to be short-circuited. The

thermal shutdown turns off the regulator in the event of

excessive heating when the die temperature reaches

145°C.

Light Load Operation

The PS0100 provides improved light load efficiency. The

internal zero current comparator monitors the inductor

current to the load and shuts off the PMOS switch once

this current reduces to some low value (typically 50mA).

This prevents the inductor current from reversing its

polarity, avoiding back-charging and thus improving the

efficiency at light loads. At that time, both the NMOS and

PMOS switches remain off. However, normal operation

starts again when the output voltage falls below the

regulation point. The IC automatically skips pulses at light

load, thus providing better efficiency.

PS0100

Enable Input

Anti-Ringing Control The PS0100 features an active-high CMOS input enable

pin (SHUTB) that allows on/off control of the regulator.

When SHUTB=Low, shutdown of the chip occurs and at

that time almost no quiescent current (<1µA) flows. The

output capacitor can be completely discharged through

the load or the feedback resistors for real output shut-

down. A discharge switch is internally connected between

VIN and SW. The Enable (SHUTB) input is TTL/CMOS

compatible. Connect SHUTB to VIN for normal operation.

When the inductor current goes to zero, there arises a

high frequency ringing at the SW pin. To prevent this, a

100Ω discharge switch is provided between SW and VIN,

so that this high frequency ringing is damped out.

Under Voltage Lockout

When the supply becomes too low (typically below 1.8V),

the PS0100 produces an internal UVLO (Under Voltage

Lockout) signal that disables the normal PWM operation

and enables the start-up oscillator to run at a fixed

frequency. At this stage, very few circuits are operational.

When the oscillator raises the supply to above 1.9V, the

UVLO signal is disabled and the normal PWM mode takes

over the operation of the start-up oscillator. This

mechanism protects the chip from producing false logic

due to low input supply.

Track Mode

The PS0100 is in track mode when VIN is greater than the

output voltage regulation point. In track mode, the

regulator runs at a fixed start-up oscillator frequency.

The start-up oscillator runs freely until V exceeds V

OUT IN.

When V falls below V

OUT IN, the start-up oscillator is

enabled again. Thus, in track mode, the regular loop

control of PWM operation remains off. Instead, the

regulator runs by intermittent oscillator operation.

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PS0100

PACKAGE INFORMATION

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PS0100

DISCLAIMERS

LIFE SUPPORT

Power IC’s products are NOT designed to be used as components in devices intended to support or sustain

human life. The use of Power IC’s products in components intended for surgical implants into the body or other

applications, in which failure of Power IC’s products could create a situation where personal death or injury

may occur, is NOT authorized without the express written approval of Power IC’s Chief Executive Officer.

Power IC will NOT be held liable for any damages or claims resulting from the use of its products in medical

applications.

MILITARY

Power IC’s products are NOT designed for use in military applications. The use of Power IC’s products in

military applications is NOT authorized without the express written approval of Power IC’s Chief Executive

Officer. Power IC will NOT be held liable for any damages or claims resulting from the use of its products in

military applications.

RIGHT TO MAKE CHANGES

Power IC reserves the right to change this document and/or this product without notice. Customers are

advised to consult their Power IC sales representativ e before ordering.

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