Over Temperature Shutdown Very Low Shutdown Current: 20µA at maximum input. Cycle-by-Cycle Over Current Protection supply voltage

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1 A, Synchronous Step-Down DC-DC Converter Advanced. Features High Efficiency: Up to 95% Internal Soft Start Up to A Output Current Over Temperature Shutdown Very Low Shutdown Current: 0µA at maximum input Cycle-by-Cycle Over Current Protection supply voltage Programmable Under Voltage Lockout Integrated 0.Ω Switch Operating Temperature: -40 C to 5 C Operating Switching Frequency from 350kHz to MHz -Pin SOP Package and HSOP Package (GT56) Option for Part-number 4.75V to 4V Input Voltage Range and support V switching Programmable Output Voltage from 0.9V to V. Current Mode Operation with External Compensation for Optimized Loop Bandwidth Part-Number GT56-GGI-TR GT57-GGI-TR Application Pin is REX. Pin is NC.. General Description The device is a high efficiency monolithic synchronous step-down bulk regulator using current mode architecture with two integrated power MOSFETs. This device delivers up to A of output current over a wide operating voltage supply range from 4.75V to 4V which makes this device ideally suited for many applications such as battery powered systems, distributed power systems, networking systems and green electronics/appliances. Current mode operation provides fast transient response and excellent load and line regulation. The switching frequency of GT56 is adjustable from 350kHz to.0mhz, allowing the use of different sizes surface mount inductors and capacitors. The fault condition protections such as cycle-by-cycle current limiting and over temperature hysteretic shutdown are implemented. In shutdown mode the converter draws 0µA of supply current at the maximum input supply voltage. Additional features include soft start, and enable. The is available in an -Pin SOP package and thermal enhanced HSOP package. 3. Applications Networking systems Distributed Power Systems Battery-Powered Systems Pre-regulator for Linear Regulators Copyright 00 Giantec Semiconductor Inc. (Giantec). All rights reserved. Giantec reserves the right to make changes to this specification and its products at any time without notice. Giantec products are not designed, intended, authorized or warranted for use as components in systems or equipment intended for critical medical or surgical equipment, aerospace or military, or other applications planned to support or sustain life. It is the customer's obligation to optimize the design in their own products for the best performance and optimization on the functionality and etc. Giantec assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and prior placing orders for products. A0 /

2 V IN 4.75~4V 7 BST REX/NC GND 3 5 V OUT 0.9~V 4 6 Figure. Typical Application Circuit A0 /

3 4. Functional Block Diagram REF BIAS V REF LDO BSTRP BST V REF ERROR AMP R s PWM SLOPE LOGIC R Q REX OSC S QB.5V - UVLO IPTAT - V REF GND THERMAL SHUTDOWN Figure. Current Mode Buck Converter A0 3/

4 5. Pin Configuration 5. GT56 SOP (Top View) 5. GT57 SOP (Top View) BST REX BST NC 3 MARKING MARKING 7 6 GND 4 5 GND 4 5 Figure 3-a. Pin Assignment Diagram (SOP Package) 5.3 GT56 HSOP (Top View) Figure 3-b. Pin Assignment Diagram (SOP Package) 5.4 GT57 HSOP (Top View) BST REX BST NC 3 DAP MARKING DAP MARKING 7 6 GND 4 5 GND 4 5 Figure 4-a. Pin Assignment Diagram (HSOP Package) Figure 4-b. Pin Assignment Diagram (HSOP Package) Note: Please see section Part Markings for detailed Marking Information. A0 4/

5 5.5 Pin Descriptions Pin No. Name I/O Function A ~0nF ceramic capacitor is connected from this pin to the pin BST I to drive the power switch s gate above Bootstrap the power supply voltage. - Supply. Connect this pin to a supply voltage from 4.75V to 4V 3 O Switching node for the converter. Connect inductor to this node. 4 GND - Ground. This pin is the voltage reference for the regulated output voltage. 5 I Feedback. An external resistor divider sets the output voltage. 6 I 7 I Compensation. Connect a compensation network to stable the loop and optimize the loop bandwidth. Enable. Pull down to ground to turn-off the converter. Leave open if it is unused. For part number GT56, setting of internal Oscillator frequency. A REX I resistor is connected from REX to GND to set the Oscillator frequency from 350 khz to.0 MHz NC NC For part number GT57, no connection. A0 5/

6 6. Functional Description 6. Operation The uses current mode PWM step-down architecture with internal top and bottom power switches. The switching frequency of the regulator is variable from 350kHz to MHz set by external resistor connected at REX pin. The default switching frequency is 350kHz. The operating description is referring to functional bloc diagram (Figure ). During normal operation, the rising edge of internal oscillator clock sets the RS latch and the top NMOS switch is turned on each switching cycle. The inductor current is sensed and amplified by current sense amplifier. Ramp compensation is summed to the error amplifier output and compare to the pin voltage with PWM comparator. The output of PWM comparator resets the RS latch, turns off the top NMOS switch until next cycle and turn on the bottom NMOS switch. During the off-time of top NMOS switch, inductor current discharges through bottom MNOS switch, which ensures the bootstrap capacitor fully charged during DCM mode. When voltage of pin exceeds 0% the normal regulation voltage of 0.9V, the over voltage comparator is tripped and turn off the high-side-switch. 6. Enable Logic low forces the into shut down mode. In shutdown, this device only draws 0µA supply current at maximum supply voltage. 6.3 Soft Start Soft-start function of limits the inrush current during start-up, and eliminates possible voltage drops of the input voltage when a battery or a high-impedance power source is connect to the. Typical start-up time is about 750µs. 6.4 Short-Circuit Protection The frequency of the oscillator is reduced to /4 of the normal frequency when the output is shorted to ground. This function ensures enough time for inductor current to decay. 6.5 Thermal Shutdown The device goes into thermal shutdown mode when the junction temperature exceeds 50 C. It continues normal operation when the temperature falls below 0 C. 6.6 Boost Function A ~0nF capacitor C BOOST is used to generate a voltage V BOOST to drive the gate of top NMOS switch above the supply voltage. The voltage across this capacitor is about 5V. 6.7 Under Voltage Lockout The under voltage lockout circuit prevents the device from miss operation at low-input voltages. It turns off the switches under undefined conditions. The minimum input voltage to start up the is 4.5V and device will shut down at 3.5V. A0 6/

7 7. Theory or operation/design procedure 7. Inductor Selection There are two main considerations when selecting optimal inductors. First, the inductor should not saturate, and second, the inductor current ripple should be small enough to achieve the desired output voltage ripple. The dc resistance of the inductance directly influences the efficiency of the converter. Therefore, an inductor with lowest dc resistance should be selected for highest efficiency. In order to avoid saturation of the inductor, the inductor should be rated at least for the maximum output current plus the inductor ripple current which is calculated as: V (V V OUT IN OUT PEAK ILOAD () L f I Where f= Switching frequency (350kHz typical) L= Inductor value Table : Recommended Components for Standard Output Voltages FS VOUT default 6.µH 0µH 0µH 5µH µh 33µH 00kHz.µH 3.6µH 4.7µH 6.µH.µH 5µH.5MHz.µH.µH.µH 3.7µH 5.µH.µH 7. Output Capacitor Selection A µf (typical) output capacitor is needed with a 6.µH inductor. Ceramic capacitors with low ESR are used for the lowest output voltage ripple. The overall output ripple voltage is the sum of the voltage spike caused by the output ESR plus the voltage ripple caused by charge and discharging the output capacitor VRIPPLE VOUT VOUT ( RESR ) () L f COUT f The largest output voltage ripple occurs at the highest input voltage. 7.3 Input Capacitor Selection In continuous mode, the input current to the device is discontinuous, therefore a low ESR input capacitor is required for best input voltage filtering and minimizing the interference with other circuits caused by high input voltage spikes. This capacitor should have a minimum value of 0µF. Since it absorbs the input switching current it requires an adequate ripple current rating. Its RMS current rating should be greater than approximately / of the output current. For insuring stable operation the capacitor should be placed as close to the IC possible. 7.5 Feedback divider resistors to set output voltage - R, R The output voltage is set by R and R, V OUT 0.9 R / R ). 0kΩ is a good typical value, and can be as high as 00kΩ. Too high impedance can make feedback node prone to noise injection particularly if unshielded inductors are used. 7.6 Frequency selection GT76 support operating switch frequency adjusts function. The frequency is set by external R EXT and internal resistor as f 350k 300k / R ) s 7.7 Stability compensation EXT Follow the following steps to compensate the IC: STEP : set the cross over frequency at /0 of the switching frequency Vref fc Gcs Gea Rcomp (3) Vout Cout Cout Rcomp Vref Gcs Gea Vout 0 fs STEP : set the zero fz at /4 frequency of the cross over (4) A0 7/

8 frequency. Ccomp Rcomp 40 fs STEP 3: If the output capacitors ESR is high enough to (5) cause a zero at lower than 4 times the cross frequency, an additional compensation capacitor Ccomp is required, and the proper value is CoutR ESR Ccomp (6) Rcomp Efficiency(%) 00.00% Efficiency vs I OUT 95.00% 90.00% 5.00% V - 5V V - 3.3V V -.5V 0.00% 75.00% 70.00% IOUT(A) Figure 4. Efficiency vs. Load Current A0 /

9 . Electrical Characteristics. Absolute Maximum Ratings Condition Min Max Supply Voltage (V IN) -0.3V V Switch Voltage (V ) -.0V V INV Bootstrap Voltage (V BST) V -0.3V Vsw6V Feedback Voltage (V ) -0.3V 6V Enable Voltage (V ) -0.3V V IN Comp Voltage (V ) -0.3V 6V Operating Junction Temperature -40 C 50 C Storage Temperature -55 C 50 C Lead Temperature 300 C Note: Stress greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions outside those indicated in the operational sections of this specification are not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. A0 9/

10 . Electrical Characteristics Electrical Characteristics (V IN =V, T A =5 C unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Units Input Voltage Range V IN V Supply Quiescent Current I Q V IN=V ma Supply Shutdown Current I SHDN V =0V µa Feedback Voltage V 4.75 V IN 4V, V <V V HS Switch On Resistance R ONH I =00mA Ω LS Switch On Resistance R ONL I =00mA Ω Internal Switch Leakage I LEAK V =0, V DS=4V µa HS Switch Current Limit I LIMH A LS Switch Current Limit I LIML From drain to source -. - A to Current Sense Transconductance G CS A/V Error Amplifier DC Gain A VEA V/V Error Amplifier Transconductance G EA I =0μA µa/v Switching Frequency ƒ khz Switching Frequency ƒ _SET R OSC=0 kω khz Short Circuit Frequency V =0V - ƒ / - khz Maximum Duty Cycle D MAX V =.0V % Minimum on Time t ON(MIN) ns Enable Threshold Voltages V IH..9.3 V Under Voltage Lockout Threshold Rising Under Voltage Lockout Threshold Hysteresis V UVLO V V UVL_TH mv Thermal Shutdown Temperature T SHDN C Thermal Shutdown Temperature Hysteresis C A0 0/

11 .3 Typical characteristics Full Load operations Operations without Load Soft-start at A Load(R=.5) Soft-start at without Load Start-up through Enable at A Load(Enable=3V) Start-up through Enable at A Load(Enable=3V) A0 /

12 Start-up through Enable without Load Load Transition (A to A) (Enable=3V) VOUT short to GND at 0.5A Load VOUT short to GND without Load VOUT Short Recovery at A Load VOUT Short Recovery at 0.5A Load A0 /

13 9. Typical Application Circuits 9. V OUT =3.3V, I LOAD =A, =350kHz V IN 4.75~4V C 0μF/5V C μf/5v 7 NC GND GT57 4 C5 nf BST 6 C4 0nF 3 5 R.3kΩ L 5μH R 30kΩ C3 μf/5v V OUT 3.3V/A R3 5kΩ 9. V OUT =5V, I LOAD =A, =350kHz V IN 6.5~4V C 0μF/5V C μf/5v 7 NC GND GT57 4 C5 nf BST 6 C4 0nF 3 5 R.3kΩ L 5μH R 5kΩ C3 μf/5v V OUT 5V/A R3 5kΩ A0 3/

14 9.3 V OUT =3.3V, I LOAD =A, =MHz V IN 4.75~4V C 0μF/5V C μf/5v 7 REX R4 60kΩ GND GT56 4 C5.nF BST 6 C4 0nF 3 5 R.3kΩ L 5μH R 30kΩ C3 μf/5v V OUT 3.3V/A R3 5kΩ 9.4 V OUT =5V, I LOAD =A, =350kHz V IN 6.5~4V C 0μF/5V R4 MΩ C μf/5v 7 REX/NC GND 4 C5 3.3nF BST 6 C4 0nF 3 5 R.3kΩ L 5μH R 5kΩ C3 μf/5v V OUT 5V/A R3 kω A0 4/

15 0. Ordering Information GT XX XX - XX X X Temperature Range Bank Commercial: 0 C ~70 C I Industrial: -40 C ~5 C Pb Status G GRE Package Type: G H SOP HSOP Part Number Production Family 5 Power Management Product; DC-DC Giantec Prefix GT Giantec Order Number Package Description Package Option -GGI-TR 5. x 4 mm SOP Tape and Reel HGI-TR 5. x 4 mm HSOP Tape and Reel 4000 A0 5/

16 . Part Markings. -GGI (Top View) G T 5 6/7 G G I Lot Number Y Y W W S V GGI Lot Number States the last 9 characters of the wafer lot information Pin Indicator YY Seal Year 00 = = = 099 WW Seal Week 0 = Week 0 = Week... 5 = Week 5 5 = Week 5 S Subcon Code J = ASESH L = ASEKS V Die Version A0 6/

17 . Package Information. SOP Detail A D E E ZD b Detail A A GAUGE PLANE e A SEATING PLANE L L Θ SYMBOLS DIMSIONS IN MILLIMETERS DIMSIONS IN INCHES MIN NOM MAX MIN NOM MAX A A b D E E e L BSC BSC L ZD Θ BSC REF BSC. 0.0 REF. -- Note:. Controlling Dimension:MM. Dimension D and E do not include Mold protrusion 3. Dimension b does not include dambar protrusion/intrusion. 4. Refer to Jedec standard MS-0 5. Drawing is not to scale A0 7/

18 3. Revision History Revision Date Descriptions A0 Jan, 0 Initial Version A0 /