SGS Thomson Microelectronics ST5R50U, ST5R50MTR, ST5R50M, ST5R33U, ST5R33MTR Datasheet

	ST5R00
®	SERIES

MICROPOWER VFM STEP-UP DC/DC CONVERTER

■VERY LOW SUPPLY CURRENT

■REGULATED OUTPUT VOLTAGE

■WIDE RANGE OF OUTPUT VOLTAGE AVAILABLE (2.5V, 2.8V, 3.0V, 3.3V, 5.0V)

■OUTPUT VOLTAGE ACCURACY ±5%

■OUTPUT CURRENT UP TO 100mA

■LOW RIPPLE AND LOW NOISE

■VERY LOW START-UP VOLTAGE

■HIGH EFFICIENCY (VOUT=5V TYP. 87%)

■FEW EXTERNAL COMPONENTS

■VERY SMALL PACKAGE: SOT23-5L, SOT-89

DESCRIPTION

The ST5R00 is an high efficiency VFM Step-up DC/DC converter for small, low input voltage or battery powered systems with ultra low quiescent supply current. The ST5Rxx accept a positive input voltage from start-up voltage to VOUT and convert it to a higher output voltage in the 2.5 to 5V range.

The ST5R00 combine ultra low quiescent supply current and high efficiency to give maximum battery life. The high switching frequency and the internally limited peak inductor current, permits the use of small, low cost inductors. Only three external components are nedeed: an inductor a diode and an output capacitor.

SOT23-5L

SOT-89

The ST5R00 is suitable to be used in a battery powered equipment where low noise, low ripple and ultra low supply current are required. The ST5R00 is available in very small packages: SOT23-5L, SOT-89.

Typical applications are pagers, cameras & video camera, cellular telephones, wireless telephones, palmtop computer, battery backup supplies, battery powered equipment.

SCHEMATIC DIAGRAM

June 2001	1/13

ST5R00

ABSOLUTE MAXIMUM RATING

Symbol	Parameter	Value	Unit
VOUT	Output Voltage	5.5	V
VIN	Input Voltage	5.5	V
VLX	LX Pin Voltage	5.5	V
ILX	LX Pin Output Current	Internally limited
Ptot	Power Dissipation @ 25oC for SOT23-5L	170 (*)	mW
Tstg	Storage Temperature Range	- 55 to 125	oC
Top	Operating Junction Temperature Range	- 25 to 85	oC

(*) Reduced by 1.7 mW for increasing in TA of 1oC over 25oC

THERMAL DATA

Symbol	Parameter	SOT23-5L	SOT-89	Unit
Rthj-case	Therma l Resistance Junction-case	63	17	°C/W

OPERATION

The ST5Rxx architecture is built around a VFM CONTROL logic core: switching frequency is set through a built in oscillator: TON time is fixed (Typ. 5μs) while TOFF time is determined by the error amplifier output, a logic signal coming from the comparison made by the Error Amplifier Stage between the signal coming from the output voltage divider network and the internal Band-Gap voltage reference (Vref). TOFF reaches a minimum (Typ. 1.7μs) when heavy load conditions are met (Clock frequency 150KHz). An over current conditions, through the internal power switch, causes a voltage drop VLX=RDSONxISW and the VLX limiter block forces the internal switch to be off, so narrowing TON time and limiting internal power dissipation. In this

case the switching frequency may be higher than the 150KHz set by the internal clock generator. VFM control ensures very low quiescent current and high conversion efficiency even with very light loads.

Since the Output Voltage pin is also used as the device Supply Voltage, the versions with higher output voltage present an higher internal supply voltage that results in lower power switch RDSON, slightly greater output power and higher efficiency. Moreover, bootstrapping allows the input voltage to sag to 0.6V (at IOUT=1mA) once the system is started.

If the input voltage exceeds the output voltage, the output will follow the input, however, the input or output voltage must not be forced above 5.5V.

Typical Application Circuit

Typical Application Efficency

(*) See application info

2/13

ST5R00

CONNECTION DIAGRAM (top view)

	SOT23-5L									SOT-89
ORDERING NUMBERS
SOT23-5L									SOT-89		Output Voltage
ST5R25M						ST5R25U					2.5 V
ST5R28M						ST5R28U					2.8 V
ST5R30M						ST5R30U					3.0 V
ST5R33M						ST5R33U					3.3 V
ST5R50M						ST5R50U					5.0 V

TYPICAL DEMOBOARD

3/13

ST5R00

ELECTRICAL CHARACTERISTICS FOR ST5R25

(VIN = 1.5V, IOUT = 10mA TA = 25oC unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.

Symbol	Parameter	Test Conditions	Min.	Typ.	Max.	Unit
VOUT	Output Voltage		2.375	2.5	2.625	V
VSTART-UP	Start-up Voltage (VIN-VF) (1)	IOUT=1mA VIN rising from 0 to 2V		0.8	1.2	V
VHOLD	Hold-on Voltage	IOUT=1mA VIN falling from 2 to 0V	0.6			V
ISUPPLY	Supply Current	To be measured at VIN, no load		16		μA
RLX(DSON)	Internal Switch RDSON	ILX=150mA		850		mΩ
ILX(leak)	Internal Leakage Current	VLX=4V, forced VOUT=3V			0.5	μA
Fosc	Maximum oscillator Frequency			150		kHz
Dty	Oscillator Duty Cycle	to be measure on Lx pin		77		%
ν	Efficency	IOUT=50mA		82		%

(1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode.

ELECTRICAL CHARACTERISTICS FOR ST5R28

(VIN = 1.7V, IOUT = 10mA TA = 25oC unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.

Symbol	Parameter	Test Conditions	Min.	Typ.	Max.	Unit
VOUT	Output Voltage		2.66	2.8	2.94	V
VSTART-UP	Start-up Voltage (VIN-VF) (1)	IOUT=1mA VIN rising from 0 to 2V		0.8	1.2	V
VHOLD	Hold-on Voltage	IOUT=1mA VIN falling from 2 to 0V	0.6			V
ISUPPLY	Supply Current	To be measured at VIN, no load		16		μA
RLX(DSON)	Internal Switch RDSON	ILX=150mA		850		mΩ
ILX(leak)	Internal Leakage Current	VLX=4V, forced VOUT=3.3V			0.5	μA
Fosc	Maximum oscillator Frequency			150		kHz
Dty	Oscillator Duty Cycle	to be measure on Lx pin		77		%
ν	Efficency	IOUT=50mA		82		%

(1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode.

ELECTRICAL CHARACTERISTICS FOR ST5R30

(VIN = 1.8V, IOUT = 10mA TA = 25oC unless otherwise specified. For external components value, unless otherwise notes, refer to the typical operating circuit.

Symbol	Parameter	Test Conditions	Min.	Typ.	Max.	Unit
VOUT	Output Voltage		2.85	3	3.15	V
VSTART-UP	Start-up Voltage (VIN-VF) (1)	IOUT=1mA VIN rising from 0 to 2V		0.8	1.2	V
VHOLD	Hold-on Voltage	IOUT=1mA VIN falling from 2 to 0V	0.6			V
ISUPPLY	Supply Current	To be measured at VIN, no load		17		μA
RLX(DSON)	Internal Switch RDSON	ILX=150mA		850		mΩ
ILX(leak)	Internal Leakage Current	VLX=4V, forced VOUT=3.5V			0.5	μA
Fosc	Maximum oscillator Frequency			150		kHz
Dty	Oscillator Duty Cycle	to be measure on Lx pin		77		%
ν	Efficency	IOUT=50mA		83		%

(1): The minimum input voltage for the IC start-up is strictly a function of the VF catch diode.

4/13