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INTEGRATED CIRCUITS
DATA SHEET
TEA1205AT High efficiency DC/DC converter
Preliminary specification File under Integrated Circuits, IC03 1998 Mar 24
Philips Semiconductors
Preliminary specification
High efficiency DC/DC converter
FEATURES • Fully integrated DC/DC converter circuit • Up conversion in 2 different modes • High efficiency over wide load range • Synchronizes to external high frequency clock • Output power up to 3.6 W (typ.) continuous, 8 W in GSM burst mode • Low quiescent power consumption • True current limit for Li-ion battery compatibility • Shut-down function • 8-pin SO package. APPLICATIONS • Cellular and cordless phones PDAs and others • Supply voltage source for low-voltage chip sets • Portable computers • Battery backup supplies • Cameras. ORDERING INFORMATION PACKAGE TYPE NUMBER NAME TEA1205AT SO8 DESCRIPTION plastic small outline package; 8 leads; body width 3.9 mm GENERAL DESCRIPTION
TEA1205AT
The TEA1205AT (see Fig.1) is a fully integrated DC/DC converter circuit using the minimum amount of external components. It is intended to be used to supply electronic circuits with supply voltages of 3.3 or 5.5 V from 2, 3 or 4 NiCd cell batteries or one Li-ion battery at an output power level up to 3.6 W (typ.) continuously, or 8 W in GSM TDMA (1 : 8) burst mode. The switching frequency of the converter can be synchronized to an external high-frequency clock. Efficient, compact and dynamic power conversion is achieved using a novel, digitally controlled Pulse Width and Frequency Modulation (PWFM) like control concept, integrated low RdsON CMOS power switches with low parasitic capacitances and synchronous rectification.
VERSION SOT96-1
1998 Mar 24
2
Philips Semiconductors
Preliminary specification
High efficiency DC/DC converter
QUICK REFERENCE DATA SYMBOL Supplies VO Vstart η output voltage start-up voltage VSEL = LOW VSEL = HIGH Efficiency; see Figs 6 and 7 efficiency up from 2.4 to 3.3 V up from 3.6 to 5.5 V Current levels Iq ISHDWN IlimN Ilx RdsON(N) RdsON(P) Timing fsw tres fsync Note switching frequency response time from standby to Pmax synchronisation input frequency 150 − − 200 25 13 quiescent current at pin 3 shut-down current NFET current limit max. continuous current at pin 5 note 1 50 − 0.9 Ilim − 60 2 Ilim − 1 mA < IL < 1.0 A 1 mA < IL < 1.0 A 80 83 90 90 5.23 3.13 1.6 5.55 3.34 2.0 PARAMETER CONDITIONS MIN. TYP.
TEA1205AT
MAX.
UNIT
5.85 3.54 2.2
V V V
95 94
% % µA µA A A Ω Ω
70 10 1.1 Ilim 1.0
Power MOSFETS pin-to-pin resistance NFET pin-to-pin resistance PFET 0.08 0.10 0.12 0.16 0.20 0.25
240 − −
kHz µs MHz
1. The NFET current limit is set by an external 1% accurate resistor Rlim connected between pin 7 and pin 6 (ground). The typical maximum instantaneous current is defined as: Ilim = 890 V/ Rlim so the use of Rlim = 315 Ω will lead to a typical maximum current value of 2.83 A. The average inductor current during current limit also depends on inductance value and resistive losses in all components in the power path. In normal application and when using Rlim = 315 Ω, the average inductor current will be limited to 2.3 A typical.
1998 Mar 24
3
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LX 5 I/V CONVERTER IIimN
BLOCK DIAGRAM
Philips Semiconductors
P-type POWER FET
handbook, full pagewidth
High efficiency DC/DC converter
3
OUT
TEA1205AT
4 START-UP CIRCUIT SENSE
CONTROL LOGIC AND MODE GEARBOX
4
TEMPERATURE PROTECTION ROM TIME COUNTER BANDGAP REFERENCE N-type POWER FET 20 MHz OSCILLATOR DIGITAL CONTROLLER sense FET 6 7 1 2 8
MGM696
GND
ILIM
VSEL
SYNC
SHDWN
Preliminary specification
TEA1205AT
Fig.1 Block diagram.
Philips Semiconductors
Preliminary specification
High efficiency DC/DC converter
PINNING SYMBOL VSEL SYNC OUT SENSE LX GND ILIM SHDWN PIN 1 2 3 4 5 6 7 8 DESCRIPTION output voltage selection input synchronisation clock input output voltage output output voltage sense input inductor connection ground current limit resistor connection shut-down input
OUT 3 SENSE 4
MGM697
TEA1205AT
handbook, halfpage
VSEL 1 SYNC 2
8 7
SHDWN ILIM GND LX
TEA1205AT
6 5
Fig.2 Pin configuration.
FUNCTIONAL DESCRIPTION Control mechanism The TEA1205AT DC/DC converter is able to operate in discontinuous or continuous conduction operation. All switching actions are completely determined by a digital control circuit which uses the output voltage level as its control input. This novel digital approach enables the use of a new pulse width and frequency modulation scheme, which ensures optimum power efficiency over the complete range of operation of the .