DATASHEET NOT RECOMMENDED FOR NEW DESIGNS POSSIBLE SUBSTITUTE PRODUCT ISL97536 EL7536 FN7396 Rev 8.00 July 13, 2006 Monolithic 1A Step-Down Regulator The EL7536 is a synchronous, integrated FET 1A step-down regulator with internal compensation. It operates with an input voltage range from 2.5V to 5.5V, which accommodates supplies of 3.3V, 5V, or a Li-Ion battery source. The output can be externally set from 0.8V to VIN with a resistive divider. Features The EL7536 features PWM mode control. The operating frequency is typically 1.4MHz. Additional features include a 100ms Power-On-Reset output, <1µA shut-down current, short-circuit protection, and over-temperature protection. • 100ms Power-On-Reset output (POR) The EL7536 is available in the 10 Ld MSOP package, making the entire converter occupy less than 0.15in2 of PCB area with components on one side only. Both packages are specified for operation over the full -40°C to +85°C temperature range. • <1µA shut-down current Ordering Information PART NUMBER (BRAND) PART MARKING • Components on one side of PCB • Max height 1.1mm MSOP10 • Internally-compensated voltage mode controller • Up to 94% efficiency • Overcurrent and over-temperature protection • Pb-free plus anneal available (RoHS compliant) Applications • PDA and pocket PC computers TAPE & REEL PACKAGE PKG. DWG. # EL7536IY BDAAA - 10 Ld MSOP MDP0043 EL7536IY-T7 BDAAA 7” 10 Ld MSOP MDP0043 EL7536IY-T13 BDAAA 13” 10 Ld MSOP MDP0043 EL7536IYZ (Note) BFAAA - 10 Ld MSOP (Pb-free) MDP0043 EL7536IYZ-T7 (Note) BFAAA 7” 10 Ld MSOP (Pb-free) MDP0043 EL7536IYZ-T13 BFAAA (Note) 13” 10 Ld MSOP (Pb-free) MDP0043 NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. • Bar code readers • Cellular phones • Portable test equipment • Li-Ion battery powered devices • Small form factor (SFP) modules Typical Application Diagram EL7536 TOP VIEW VS (2.5V to 5.5V) R3 100 C2 10µF LX EL7536 R5 100k EL7536 (10 LD MSOP) TOP VIEW 1 SGND FB 10 2 PGND VO 9 3 LX R1* 124k POR R4 100k R6 100k 1.8µH C1 10µF VDD C3 0.1µF VO L1 VIN EN Pinout FN7396 Rev 8.00 July 13, 2006 • Less than 0.15in2 (0.97cm2) footprint for the complete 1A converter FB RSI PGND SGND R2* 100k VO C4 470pF (1.8V @ 1A) * VO = 0.8V * (1 + R1 / R2) POR 8 4 VIN EN 7 5 VDD RSI 6 Page 1 of 9 EL7536 Absolute Maximum Ratings (TA = 25°C) VIN, VDD, POR to SGND . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V LX to PGND . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VIN + +0.3V) RSI, EN, VO, FB to SGND . . . . . . . . . . . . . . . -0.3V to (VIN + +0.3V) PGND to SGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +0.3V Peak Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2A Operating Ambient Temperature . . . . . . . . . . . . . . . .-40°C to +85°C Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +125°C CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typ values are for information purposes only. Unless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA Electrical Specifications PARAMETER VDD = VIN = VEN = 3.3V, C1 = C2 = 10µF, L = 1.8µH, VO = 1.8V, unless otherwise specified. DESCRIPTION CONDITIONS MIN TYP MAX UNIT 790 800 810 mV 250 nA 2.5 5.5 V DC CHARACTERISTICS VFB Feedback Input Voltage IFB Feedback Input Current VIN, VDD Input Voltage VIN,OFF Minimum Voltage for Shutdown VIN falling 2 2.2 V VIN,ON Maximum Voltage for Startup VIN rising 2.2 2.4 V IDD Supply Current PWM, VIN = VDD = 5V 400 500 µA EN = 0, VIN = VDD = 5V 0.1 1 µA PMOS FET Resistance VDD = 5V, wafer test only 70 100 m RDS(ON)-NMOS NMOS FET Resistance VDD = 5V, wafer test only 45 75 m RDS(ON)-PMOS ILMAX Current Limit TOT,OFF Over-temperature Threshold TOT,ON 1.5 A T rising 145 °C Over-temperature Hysteresis T falling 130 °C IEN, IRSI EN, RSI Current VEN, VRSI = 0V and 3.3V VEN1, VRSI1 EN, RSI Rising Threshold VDD = 3.3V VEN2, VRSI2 EN, RSI Falling Threshold VDD = 3.3V VPOR Minimum VFB for POR, WRT Targeted VFB Value VFB rising POR Voltage Drop ISINK = 5mA VOLPOR VFB falling -1 1 V 2.4 V 0.8 V 95 86 % % 35 70 mV 1.5 1.75 MHz 25 50 ns AC CHARACTERISTICS FPWM PWM Switching Frequency tRSI Minimum RSI Pulse Width tSS Soft-start Time tPOR Power On Reset Delay Time FN7396 Rev 8.00 July 13, 2006 1.4 Guaranteed by design 650 80 100 µs 120 ms Page 2 of 9 EL7536 Pin Descriptions PIN NUMBER PIN NAME PIN FUNCTION 1 SGND Negative supply for the controller stage 2 PGND Negative supply for the power stage 3 LX Inductor drive pin; high current digital output with average voltage equal to the regulator output voltage 4 VIN Positive supply for the power stage 5 VDD Power supply for the controller stage 6 RSI Resets POR timer 7 EN Enable 8 POR 9 VO Output voltage sense 10 FB Voltage feedback input; connected to an external resistor divider between VO and SGND for variable output Power on reset open drain output Block Diagram VDD VO + - 10pF 124K FB 5M + PWM COMPENSATION 100K CLOCK 1.4MHz CURRENT LIMIT + PWM COMPARATOR P-DRIVER LX CONTROL LOGIC RAMP GENERATOR 1.8µ 1.8V 1A EN EN SOFTSTART 10µF 2.5V3.5V VIN + – BANDGAP REFERENCE UNDERVOLTAGE LOCKOUT RSI PGND 100K TEMPERATURE SENSE SGND FN7396 Rev 8.00 July 13, 2006 10µF N-DRIVER POR PG POR Page 3 of 9 EL7536 Performance Curves and Waveforms All waveforms are taken at VIN = 3.3V, VO = 1.8V, IO = 1A with component values shown on page 1 at room ambient temperature, unless otherwise noted. 100 VIN=5V 100 VO=3.3V 95 95 VO=2.5V 90 EFFICIENCY (%) 90 EFFICIENCY (%) VIN=3.3V 85 VO=1.8V 80 VO=2.5V VO=1.2V 75 70 85 VO=1V 80 VO=1.8V VO=1.2V 75 70 65 65 60 60 0 200 400 600 800 1000 0 200 400 IO (mA) FIGURE 1. EFFICIENCY VIN=5V IO=0A FS (MHz) 1.42 0.0% 1.4 VIN=3.3V IO=0A 1.38 1.36 -0.1% VIN=3.3V -0.2% VIN=5V -0.3% -0.4% 1.34 -0.5% 1.32 -50 0 50 100 150 0 0.2 0.4 0.8 1 FIGURE 4. LOAD REGULATIONS FIGURE 3. FS vs JUNCTION TEMPERATURE 0.1% 12 0.0% VIN=5V IO=0A 10 VIN=3.3V IO=0A 8 -0.2% -0.3% IIN (mA) VO CHANGES 0.6 IO (A) TA (°C) -0.1% 1000 0.1% VIN=3.3V IO=1A VIN=5V IO=1A 800 FIGURE 2. EFFICIENCY VO CHANGES 1.44 600 IO (mA) VIN=3.3V IO=1A -0.4% 6 4 -0.5% -0.6% -0.7% -50 2 VIN=5V IO=1A 0 50 100 150 TJ (°C) FIGURE 5. LOAD/LINE REGULATIONS vs JUNCTION TEMPERATURE FN7396 Rev 8.00 July 13, 2006 0 2.5 3 3.5 4 4.5 5 VIN (V) FIGURE 6. NO LOAD INPUT CURRENT Page 4 of 9 EL7536 Performance Curves and Waveforms (Continued) All waveforms are taken at VIN = 3.3V, VO = 1.8V, IO = 1A with component values shown on page 1 at room ambient temperature, unless otherwise noted. VIN (2V/d) VIN (1V/d) VO (2V/d) IIN (0.5A/d) POR (2V/d) VO (1V/d) 50ms/d 0.5ms/d FIGURE 8. START-UP 2 FIGURE 7. START-UP 1 VIN (2V/d) VO (2V/d) 0.75A 0.25A IO RSI (2V/d) VO 20mV/d POR (2V/d) 50ms/d 0.2ms/d FIGURE 9. POR FUNCTION FIGURE 10. TRANSIENT RESPONSE VIN 100mV/d 0.5A/d iL VLX 2V/d VO 10mV/d 1µs/d FIGURE 11. STEADY-STATE FN7396 Rev 8.00 July 13, 2006 Page 5 of 9 EL7536 Performance Curves and Waveforms (Continued) 0.5 0.4 JA 0.3 M SO P =2 06 10 °C /W 0.2 0.1 0 0 25 50 75 85 100 125 150 AMBIENT TEMPERATURE (°C) FIGURE 12. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE FN7396 Rev 8.00 July 13, 2006 ALLOWABLE POWER DISSIPATION (W) 0.6 JEDEC JESD51-3 LOW EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 1.00 JEDEC JESD51-7 HIGH EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 0.90 0.80 0.70 0 P1 /W °C SO M 115 = A J ALLOWABLE POWER DISSIPATION (W) All waveforms are taken at VIN = 3.3V, VO = 1.8V, IO = 1A with component values shown on page 1 at room ambient temperature, unless otherwise noted. 0.60 0.50 0.40 0.30 0.20 0.10 0 0 25 50 75 85 100 125 150 AMBIENT TEMPERATURE (°C) FIGURE 13. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE Page 6 of 9 EL7536 Applications Information Product Description The EL7536 is a synchronous, integrated FET 1A step-down regulator which operates from an input of 2.5V to 6V. The output voltage is user-adjustable with a pair of external resistors. The internally-compensated controller makes it possible to use only two ceramic capacitors and one inductor to form a complete, very small footprint 1A DC:DC converter. Start-Up and Shut-Down When the EN pin is tied to VIN, and VIN reaches approximately 2.4V, the regulator begins to switch. The output voltage is gradually increased to ensure proper softstart operation. When the EN pin is connected to a logic low, the EL7536 is in the shut-down mode. All the control circuitry and both MOSFETs are off, and VOUT falls to zero. In this mode, the total input current is less than 1µA. When the EN reaches logic HI, the regulator repeats the start-up procedure, including the soft-start function. PWM Operation In the PWM mode, the P channel MOSFET and N channel MOSFET always operate complementary. When the PMOSFET is on and the NMOSFET off, the inductor current increases linearly. The input energy is transferred to the output and also stored in the inductor. When the P channel MOSFET is off and the N channel MOSFET on, the inductor current decreases linearly, and energy is transferred from the inductor to the output. Hence, the average current through the inductor is the output current. Since the inductor and the output capacitor act as a low pass filter, the duty cycle ratio is approximately equal to VO divided by VIN. The output LC filter has a second order effect. To maintain the stability of the converter, the overall controller must be compensated. This is done with the fixed internally compensated error amplifier and the PWM compensator. Because the compensations are fixed, the values of input and output capacitors are 10µF to 22µF ceramic. The inductor is nominally 1.8µH, but 1.5µA to 2.2µH can be used. 100% Duty Ratio Operation EL7536 utilizes CMOS power FET's as the internal synchronous power switches. The upper switch is a PMOS and lower switch a NMOS. This not only saves a boot capacitor, it also allows 100% turn-on of the upper PFET switch, achieving VO close to VIN. The maximum achievable VO is, V O = V IN – R L + R DSON1 I O FN7396 Rev 8.00 July 13, 2006 Where RL is the DC resistance on the inductor and RDSON1 the PFET on-resistance, nominal 70m at room temperature with tempco of 0.2m/°C. As the input voltage drops gradually close or even below the preset VO, the converter gets into 100% duty ratio. At this condition, the upper PFET needs some minimum turn-off time if it is turned off. This off-time is related to input/output conditions. This makes the duty ratio appears randomly and increases the output ripple somewhat until the 100% duty ratio is reached. Larger output capacitor could reduce the random-looking ripple. Users need to verify if this condition has adverse effect on overall circuit if close to 100% duty ratio is expected. RSI/POR Function When powering up, the open-collector Power-On-Reset output holds low for about 100ms after VO reaches the preset voltage. When the active-HI reset signal RSI is issued, POR goes to low immediately and holds for the same period of time after RSI comes back to LOW. The output voltage is unaffected. (Please refer to the timing diagram). When the function is not used, connect RSI to ground and leave open the pull-up resister R4 at POR pin. The POR output also serves as a 100ms delayed Power Good signal when the pull-up resister R4 is installed. The RSI pin needs to be directly (or indirectly through a resister R6) connected to Ground for this to function properly. VO MIN 25ns RSI 100ms 100ms POR FIGURE 14. RSI & POR TIMING DIAGRAM Output Voltage Selection Users can set the output voltage of the converter with a resister divider, which can be chosen based on the following formula: R 2 V O = 0.8 1 + ------- R 1 Component Selection Because of the fixed internal compensation, the component choice is relatively narrow. We recommend 10µF to 22µF multi-layer ceramic capacitors with X5R or X7R rating for both the input and output capacitors, and 1.5µH to 2.2µH inductance for the inductor. Page 7 of 9 EL7536 At extreme conditions (VIN < 3V, IO > 0.7A, and junction temperature higher than 75°C), input cap C1 is recommended to be 22µF. Otherwise, if any of the above 3 conditions is not true, C1 can remain as low as 10µF. The RMS current present at the input capacitor is decided by the following formula: V O V IN - V O I INRMS = ------------------------------------------------ I O V IN This is about half of the output current IO for all the VO. This input capacitor must be able to handle this current. The inductor peak-to-peak ripple current is given as: V IN - V O V O I IL = -------------------------------------------L V IN f S • L is the inductance • fS the switching frequency (nominally 1.4MHz) The inductor must be able to handle IO for the RMS load current, and to assure that the inductor is reliable, it must handle the 1.5A surge current that can occur during a current limit condition. In addition to decoupling capacitors and inductor value, it is important to properly size the phase-lead capacitor C4 (Refer to the Typical Application Diagram). The phase-lead capacitor creates additional phase margin in the control loop by generating a zero and a pole in the transfer function. As a general rule of thumb, C4 should be sized to start the phaselead at a frequency of ~2.5kHz. The zero will always appear at lower frequency than the pole and follow the equation below: 1 f Z = ---------------------2R 2 C 4 Over a normal range of R2 (~10-100k), C4 will range from ~470-4700pF. The pole frequency cannot be set once the zero frequency is chosen as it is dictated by the ratio of R1 and R2, which is solely determined by the desired output set point. The equation below shows the pole frequency relationship: Thermal Shut-Down Once the junction reaches about 145°C, the regulator shuts down. Both the P channel and the N channel MOSFETs turn off. The output voltage will drop to zero. With the output MOSFETs turned off, the regulator will soon cool down. Once the junction temperature drops to about 130°C, the regulator will restart again in the same manner as EN pin connects to logic HI. Thermal Performance The EL7536 is in a fused-lead MSOP10 package. Compared with regular MSOP10 package, the fused-lead package provides lower thermal resistance. The JA is 100°C/W on a 4-layer board and 125°C/W on 2-layer board. Maximizing the copper area around the pins will further improve the thermal performance. Layout Considerations The layout is very important for the converter to function properly. The following PC layout guidelines should be followed: • Separate the Power Ground ( ) and Signal Ground ( connect them only at one point right at the pins • Place the input capacitor as close to VIN and PGND pins as possible • Make the following PC traces as small as possible: - from LX pin to L - from CO to PGND • If used, connect the trace from the FB pin to R1 and R2 as close as possible • Maximize the copper area around the PGND pin • Place several via holes under the chip to additional ground plane to improve heat dissipation The demo board is a good example of layout based on this outline. Please refer to the EL7536 Application Brief. 1 f P = --------------------------------------2 R 1 R 2 C 4 Current Limit and Short-Circuit Protection The current limit is set at about 1.5A for the PMOS. When a short-circuit occurs in the load, the preset current limit restricts the amount of current available to the output, which causes the output voltage to drop below the preset voltage. In the meantime, the excessive current heats up the regulator until it reaches the thermal shut-down point. FN7396 Rev 8.00 July 13, 2006 ); Page 8 of 9 EL7536 Mini SO Package Family (MSOP) 0.25 M C A B D MINI SO PACKAGE FAMILY (N/2)+1 N E MDP0043 A E1 PIN #1 I.D. 1 B (N/2) e H C SEATING PLANE 0.10 C N LEADS MSOP8 MSOP10 TOLERANCE NOTES A 1.10 1.10 Max. - A1 0.10 0.10 ±0.05 - A2 0.86 0.86 ±0.09 - b 0.33 0.23 +0.07/-0.08 - c 0.18 0.18 ±0.05 - D 3.00 3.00 ±0.10 1, 3 E 4.90 4.90 ±0.15 - E1 3.00 3.00 ±0.10 2, 3 e 0.65 0.50 Basic - L 0.55 0.55 ±0.15 - L1 0.95 0.95 Basic - N 8 10 Reference Rev. C 6/99 0.08 M C A B b SYMBOL NOTES: 1. Plastic or metal protrusions of 0.15mm maximum per side are not included. 2. Plastic interlead protrusions of 0.25mm maximum per side are not included. L1 3. Dimensions “D” and “E1” are measured at Datum Plane “H”. A 4. Dimensioning and tolerancing per ASME Y14.5M-1994. c SEE DETAIL "X" A2 GAUGE PLANE A1 L 0.25 3° ±3° DETAIL X © Copyright Intersil Americas LLC 2003-2006. All Rights Reserved. All trademarks and registered trademarks are the property of their respective owners. For additional products, see www.intersil.com/en/products.html Intersil products are manufactured, assembled and tested utilizing ISO9001 quality systems as noted in the quality certifications found at www.intersil.com/en/support/qualandreliability.html Intersil products are sold by description only. Intersil may modify the circuit design and/or specifications of products at any time without notice, provided that such modification does not, in Intersil's sole judgment, affect the form, fit or function of the product. Accordingly, the reader is cautioned to verify that datasheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com FN7396 Rev 8.00 July 13, 2006 Page 9 of 9