SM8172A 2-output Power Supply IC 1. OVERVIEW The SM8172A is a 2-output power supply IC that incorporates a step-down DC/DC converter and series regulator with built-in reset circuit. The DC/DC converter is a PWM-type synchronous rectifier. The SM8172A has soft start, overcurrent detection, supply undervoltage lockout, and thermal shutdown circuits built-in, making it ideal as a supply voltage source IC for large-scale LSIs that operate from a 5V supply. 2. FEATURES ■ ■ ■ ■ Input voltage range: 4.5 to 5.5V Standby current: 0.01µA (typ) Series regulator • Feedback-type current limiter to reduce output current when outputs are short-circuit • Output voltage: 3.3V (available for optional setting from 2.1 to 3.6V by 0.1V-step) • Maximum output current: 450mA • Voltage accuracy: ± 2% (VIN = 5.0V, Ta = 25°C) DC/DC converter • Current-mode operation for excellent transient response • Output voltage: 0.8 to 1.8V (typ, selectable by external resistor) • Maximum output current: 900mA • Operating frequency: 2MHz (typ) • Voltage accuracy: ± 2% (FB pin, VIN = 5.0V, Ta = 25°C, DCOUT = 1.0V) ■ ■ ■ Reset circuit built-in • Reset detection voltage: 3.7V (typ) (available for optional setting from 3.2 to 4.2V by 0.1V-step) • Reset return delay time: 65ms (typ) (50ms, 32ms, 16ms, and 8ms selectable with option) Various protection circuit built-in • Startup soft start circuit built-in • Overtemperature thermal shutdown (TSD) circuit built-in • Supply undervoltage lockout (UVLO) circuit built-in Package: 10-pin SON 3. APPLICATIONS ■ ■ ■ ■ ODD DVD player/recorder Next-generation DVD player/recorder Electronic equipment 4. TYPICAL APPLICATION CIRCUIT 5.0V R3 10kΩ VIN1 RESETN output RESETN C1 10µF PGND VIN2 C2 10µF LDOUT Regulator output C5 3.3µF GND R2 330kΩ DC/DC control ENDCO FB C3 8pF Regulator control ENLDO LX L 2.2µH R1 220kΩ C4 4.7µF DCOUT (1.0V) Note. RESETN is open-drain, therefore, please take care so that the High level signal does not exceed the absolute maximum rating of IC which receives the reset signal. Besides, if the rest signal is not used, RESETN should be connected to GND. 5. ORDERING INFORMATION Device Package SM8172AD 10-pin SON SEIKO NPC CORPORATION —1 SM8172A 6. PINOUT (Top view) 10 RESETN VIN2 1 LDOUT 2 9 FB GND 3 8 VIN1 ENDCO 4 7 LX ENLDO 5 6 PGND 7. PIN DESCRIPTION Number Name I/O 1 VIN2 – Supply voltage (series regulator, internal circuits)*1 Function 2 LDOUT O Series regulator output*2 3 GND – Ground (internal circuits) 4 ENDCO Ip*3 Output enable (DC/DC converter) 5 ENLDO Ip*3 Output enable (series regulator) 6 PGND – Ground (DC/DC converter output circuit) 7 LX O DC/DC converter coil drive*4 8 VIN1 – Supply voltage (DC/DC converter output circuit)*1 9 FB I DC/DC converter feedback connection*5 10 RESETN O Reset signal output (active-LOW, open-drain output)*6 *1. VIN1 and VIN2 should have the same voltage potential. *2. When the series regulator is not used, LDOUT pin should be open and not be connected to GND. *3. Ip = Input with pull-down resistor built-in *4. When the DC/DC converter is not used, LX pin should be open and not be connected to GND or the supply. *5. When the DC/DC converter is not used, FB pin should be connected to GND. *6. When the reset signal is not used, RESETN pin should be connected to GND. 8. BLOCK DIAGRAM 10kΩ Delay circuits VIN2 detector 5.0V VIN2 10µF GND Current protection RESETN output RESETN − ERR + LDOUT Soft start LDOUT output (3.3V) 3.3µF Vref ENDCO + Thermal protection ERR 330kΩ FB − ENLDO OSC Soft start Current protection Current mode PWM control Output control VIN1 5.0V 8pF LX 220kΩ 10µF 2.2µH 4.7µF DCOUT (1.0V) PGND SEIKO NPC CORPORATION —2 SM8172A 9. ABSOLUTE MAXIMUM RATINGS Parameter Symbol Rating Unit VIN −0.3 to 6.0 V VENDCO, VENLDO, VFB −0.3 to VIN + 0.3 V Output pin voltage range 1 VLX, VLDOUT −0.3 to VIN + 0.3 V Output pin voltage range 2 VRESETN −0.3 to 6.0 V ILX 1.5 A ILDOUT 700 mA PD 2000 (Ta = 25°C)*1 mW TJMAX +125 °C Tstg −55 to +125 °C Supply voltage range Input pin voltage range LX output current LDOUT output current Power dissipation Junction temperature Storage temperature range *1. 101.5 × 105.0 × 1.6mm, wiring ratio 250%, FR-4, 4-layer board (thermal vias, die pad connections) Note that the ratings will vary depending on the board specifications, footprint pattern, and other factors. Note. The device may be damaged or deteriorated if any of the above parameter ratings is exceeded. Power dissipation PD [mW] 2500 2000 1500 1000 500 0 0 50 25 75 Ambient temperature Ta [°C] 10. RECOMMENDED OPERATING CONDITIONS Rating Parameter Supply voltage Operating ambient temperature Pin Symbol VIN1, 2 VIN − Ta Conditions VIN1 = VIN2 Unit min typ max 4.5 5.0 5.5 V −20 +25 +85 °C SEIKO NPC CORPORATION —3 SM8172A 11. ELECTRICAL CHARACTERISTICS Note. The specifications of “ELECTRICAL CHARACTERISTICS” are shown by using “TYPICAL APPLICATION CIRCUIT” on page 13. 11-1. Common Blocks VIN1 = VIN2 = 5.0V, GND = PGND = 0V, Ta = 25°C unless otherwise noted. Rating Parameter Standby current Pin VIN1, 2 HIGH-level input voltage LOW-level input voltage ENDCO, ENLDO HIGH-level input current RESETN output current RESETN Reset circuit operating voltage VIN2 Reset circuit return delay time Under voltage lockout RESETN VIN2 Symbol Condition Unit min typ max – 0.01 1 µA VIH 1.8 – – V VIL – – 0.6 V IIH – 5.0 10 µA 20 – – mA ISTB Standby mode (ENDCO = ENLDO = L), No load on inputs/outputs IRESETN VRESETN = 1.0V VRESETNL When VIN falls 3.5 3.7 3.9 V VRESETNH When VIN rises 3.7 3.9 4.1 V tRESETN When VIN rises – 65 – ms VUVLOL When VIN falls 2.7 3.0 3.3 V VUVLOH When VIN rises 2.9 3.2 3.5 V TSD operating temperature – TSD – 170 – °C TSD hysteresis – TSDHYS – 20 – °C 11-2. Series Regulator VIN1 = VIN2 = 5.0V, GND = PGND = 0V, Ta = 25°C unless otherwise noted. Rating Parameter Pin Symbol Condition No load Unit min typ max – 0.1 0.25 mA 0.5 1 2 ms Current consumption VIN1, 2 IDD_LDO Soft start time LDOUT tSS_LDO Output voltage LDOUT VLDO ILDO = 10mA 3.23 3.3 3.37 V Maximum output current*1 LDOUT ILDO VIN2 = 4.5V, LDOUT = 3.3V 450 – – mA Input stability LDOUT ∆VOUT1 4.5V ≤ VIN2 ≤ 5.5V, ILDO = 30mA – 0.1 0.35 %/V Load stability LDOUT ∆VOUT2 VIN2 = 5.0V, 1mA ≤ ILDO ≤ 300mA – 40 – mV Overcurrent protection circuit operating current LDOUT IOS – 700 – mA *1. The output voltage difference at ILDO = 1mA and ILDO = 450mA is within ± 3%. SEIKO NPC CORPORATION —4 SM8172A 11-3. DC/DC Converter VIN1 = VIN2 = 5.0V, GND = PGND = 0V, Ta = 25°C unless otherwise noted. Rating Parameter Pin Symbol Condition Unit min typ max Current consumption 1 VIN1, 2 IDD1 No load, switching stopped – 0.35 0.75 mA Current consumption 2 FB = VIN1, LX = Open – 2.5 5.5 mA VIN1, 2 IDD2 Soft start time*1*2 – tSS 0.2 0.6 1.0 ms Output voltage range*2 – VDCO 0.8 – 1.8 V FB voltage FB VFB 0.588 0.6 0.612 V Maximum output current*2*3 – IDCO 900 – – mA Switching frequency LX fOSC 1.7 2.0 2.3 MHz Supply-side switch ON resistance LX RONP IDCO = 50mA – 0.3 – Ω GND-side switch ON resistance LX RONN IDCO = –50mA – 0.3 – Ω LX leakage current LX ILEAKLX Standby mode, LX = 1/2VIN –1.0 – 1.0 µA Overcurrent protection circuit operating current LX ILIMITLX Supply-side switch – 1.5 – A *1. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the DC/DC converter output raise time. If the maximum load current is output after soft start time startup, the output voltage does not fall. But, if the maximum load current is output before soft start time startup, it should be careful that the output voltage may fall. LX switching start High ENDCO Low 1.5A (typ) Current limit Soft start time 1.8V 1.0V DCOUT 42µsec (typ) 28µsec (typ) The LX starts the switching operation after 42µs from ENDCO rising. After switching operation startup, the output current limit operates like linear increase (load current = 0A). The DC/DC converter output voltage rise time varies with the load current, output capacitance, and other conditions. SEIKO NPC CORPORATION —5 SM8172A *2. The DC/DC converter output voltage (DCOUT) is determined by the external resistors as given by the following equation. The SM8172A DC/DC converter controls the output to maintain the FB pin voltage of 0.6V. Example settings DCOUT = 0.6 × (R1 + R2) R2 DCOUT [V] DCOUT R1 [kΩ] R2 [kΩ] C3 [pF] 0.8 200 600 8 1.000 200 300 8 1.200 200 200 8 1.502 200 133 8 1.800 200 100 8 LX SM8172 C3 R1 The E-12 series usage example FB R2 DCOUT [V] R1 [kΩ] R2 [kΩ] C3 [pF] 1.0 220 330 8 1.2 220 220 8 1.5 150 100 10 *3. The output voltage difference at IDCO = 100mA and IDCO = 900mA is within ± 3%. ■ Accuracy of output voltage The accuracy of DCOUT output voltage is affected by the FB pin voltage accuracy (0.6V ± 2%) and the external resistor accuracy (R1, R2). If the external resistor of ± 1% accuracy is used, the accuracy of DCOUT output voltage shows ± 3% accuracy including the FB pin voltage accuracy ± 2%. SEIKO NPC CORPORATION —6 SM8172A 12. FUNCTIONAL DESCRIPTION 12-1. Series Regulator 12-1-1. Basic Operation The SM8172A is equipped with a series regulator that drives a maximum 450mA load current at a fixed 3.3V output voltage. 12-1-2. Soft Start Function A soft start circuit is built-in to prevent output voltage overshoot and inrush current at startup. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the series regulator output voltage rise time. The time varies with the load current, output capacitance, and other conditions. 12-1-3. Overcurrent Protection Function The series regulator overcurrent protection function uses a foldback method. When the output current exceeds the overcurrent protection circuit operating current limit value of 700mA (typ), the output current and output voltage are dropped, and the output short-circuit current is 80mA (typ). Normal operation is restored when the overcurrent condition is resolved. 3.3V (typ) LDOUT (regulator output) Output short-circuit current 80mA (typ) Overcurrent protection current 700mA (typ) ILDOUT (regulator output current) SEIKO NPC CORPORATION —7 SM8172A 12-2. DC/DC Converter 12-2-1. Basic Operation The SM8172A DC/DC converter is a step-down converter that is controlled using a 2MHz switching frequency current-mode PWM waveform, and which incorporates a MOSFET synchronous rectifier. 12-2-2. Soft Start Function A soft start circuit is built-in to prevent output voltage overshoot and inrush current at startup. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the DC/DC converter output voltage rise time. The time varies with the load current, output capacitance, and other conditions. 12-2-3. Overcurrent Protection Function The P-channel MOSFET is turned OFF when the inductor current exceeds the current limit (1.5A). Normal operation is restored when the overcurrent condition is resolved. Overcurrent detector Pch MOS OFF 1.5A LX VIN1 Overloaded status Inductor current Output control Normal operation when resolving overload 12-3. Reset Function When the supply voltage is within the rated range, the RESETN output is high-impedance (Hi-Z). When the supply voltage falls below 3.7V (typ), the undervoltage detector circuit operates, setting the RESETN output LOW. When the supply voltage subsequently rises above 3.9V (typ), the RESETN output goes high-impedance again. However, when the supply voltage rises above 3.9V (typ), a built-in delay circuit sets the RESETN output to high-impedance after a delay of 65ms (typ). When at standby status, the RESETN output is LOW. When standby status is released, the RESETN output goes high-impedance after delay time if the supply voltage is more than 3.9V (typ). SEIKO NPC CORPORATION —8 SM8172A 12-4. Supply Undervoltage Lockout Function In addition to the reset function, when the VIN2 supply falls below 3.0V (typ), the undervoltage lockout function operates, stopping the DC/DC converter and series regulator outputs. When the VIN2 supply subsequently rises above 3.2V (typ), the outputs start again. VRESETNH VRESETNL VUVLOH VUVLOL VIN2 Reset return delay time 65msec (typ) VRESETN (Pull-up) 800µsec (typ)*1 LDOUT (regulator output) VDCOUT VLDOUT LDOUT (regulator output) *1 70µsec (typ) DCOUT (DC/DC output) DCOUT (DC/DC output) DC/DC soft start time*2 0.6msec (typ) LDO soft start time*2 1msec (typ) DC/DC, regulator output stop by UVLO lockout *1. A time interval example for a typical application circuit with no load. The series regulator and DC/DC converter output voltage rise times may vary with the load current, output capacitance, and other conditions. *2. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the series regulator and DC/DC converter output raise time. SEIKO NPC CORPORATION —9 SM8172A 12-5. Thermal Shutdown (TSD) Protection Circuit When the chip temperature rises above approximately 170°C (typ) for any reason whatsoever, the thermal shutdown circuit operates, stopping all outputs. When the chip temperature falls below 150°C (typ), the outputs start again. TSD 170 C (typ) TSD-TSDHYS 150 C (typ) Chip temperature [ C] 800µsec (typ)*1 LDOUT (regulator output) LDOUT (regulator output) VDCOUT VLDOUT *1 70µsec (typ) DCOUT (DC/DC output) DCOUT (DC/DC output) DC/DC, regulator output stop by thermal shutdown DC/DC soft start time*2 0.6msec (typ) VRESETN (Pull-up) LDO soft start time*2 1msec (typ) Reset return delay time 65msec (typ) *1. A time interval example for a typical application circuit with no load. The series regulator and DC/DC converter output voltage rise times may vary with the load current, output capacitance, and other conditions. *2. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the series regulator and DC/DC converter output raise time. 12-6. State of Each Output when Protection Function Operates The output states of RESETN, DCOUT, and LDOUT when various circuit protection functions operate are shown in the following table. When various protection functions operate Pins Normal operation RESETN DCOUT*1 LDOUT Series regulator DC/DC converter overcurrent protection overcurrent protection IOS = 700mA (typ) ILIMITLX = 1.5A (typ) RESET voltage VIN2 ≤ 3.9V (typ) Under voltage lockout VIN2 ≤ 3.2V (typ) TSD TSD = 170°C (typ) Hi-Z L L L Hi-Z Hi-Z 1.0V 1.0V 0V (Disable) 0V (Disable) 1.0V < 1.0V 3.3V 3.3V 0V (Disable) 0V (Disable) < 3.3V 3.3V *1. When the DC/DC converter output voltage is set to 1.0V. Note. The RESETN output is unaffected by the overcurrent protection function. The DCOUT and LDOUT outputs are unaffected by the reset voltage. SEIKO NPC CORPORATION —10 SM8172A 12-7. Standby Mode When both ENDCO and ENLDO are LOW, the device switches to standby mode, and all the RESETN, converter, and regulator outputs stop. 12-8. Timing Diagrams 12-8-1. Supply Voltage (VIN1 = VIN2 = ENDCO = ENLDO) VRESETNH VRESETNL VUVLOH VUVLOL VIN1 VIN2 ENABLE VRESETN (Pull-up) Reset return delay time 65msec (typ) 800µsec (typ)*1 LDOUT (regulator output) VDCOUT VLDOUT *1 70µsec (typ) DCOUT (DC/DC output) DC/DC, regulator output stop by UVLO lockout DC/DC soft start time*2 0.6msec (typ) DC/DC, regulator output permission LDO soft start time*2 1msec (typ) *1. A time interval example for a typical application circuit with no load. The series regulator and DC/DC converter output voltage rise times may vary with the load current, output capacitance, and other conditions. *2. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the series regulator and DC/DC converter output raise time. Note. When the supply voltage is below approximately 0.8V, there is insufficient drive for the IC to operate normally and the RESETN output level is undefined. Normally, a pull-up resistor is connected to RESETN, which sets the RESETN output level to pull-up voltage. SEIKO NPC CORPORATION —11 SM8172A 12-8-2. Enable Control ENDCO ENLDO *1 VDCOUT 70µsec (typ) DC/DC soft start time*2 0.6msec (typ) 800µsec (typ)*1 VLDOUT LDO soft start time*2 1msec (typ) Reset return delay time 65ms (typ) VRESTEN (pull-up) Standby mode when both ENDCO and ENLDO are LOW level *1. A time interval example for a typical application circuit with no load. The series regulator and DC/DC converter output voltage rise times may vary with the load current, output capacitance, and other conditions. *2. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the series regulator and DC/DC converter output raise time. SEIKO NPC CORPORATION —12 SM8172A 13. TYPICAL APPLICATION CIRCUIT 5.0V R3 10kΩ VIN1 RESETN output RESETN C1 10µF PGND VIN2 C2 10µF LDOUT Regulator output C5 3.3µF GND R2 330kΩ DC/DC control FB ENDCO C3 8pF Regulator control ENLDO LX L 2.2µH R1 220kΩ C4 4.7µF DCOUT (1.0V) Recommended parts list L : 2.2µH 1002AS-2R2M (TOKO) NR4018T2R2M (TAIYO YUDEN) VLF4014ST2R2M1R9 (TDK) R1, R2 : 220kΩ, 330kΩ – R3 : 10kΩ – C1, C2 : 10µF Ceramic Capacitor C2012X5R1A106K (TDK) Ceramic Capacitor GRM219B31A106K (Murata) C3 : 8pF Ceramic Capacitor C4 4.7µF Ceramic Capacitor GRM219B31A475K (Murata) C5 : 3.3µF Ceramic Capacitor GRM219B31A335K (Murata) Note. RESETN is open-drain, therefore, please take care so that the High level signal does not exceed the absolute maximum rating of IC which receives the reset signal. Besides, if the rest signal is not used, RESETN should be connected to GND. SEIKO NPC CORPORATION —13 SM8172A 14. USAGE NOTES 14-1. Select of Inductance (L) It recommends 2.2µH of Inductance (L) for SM8172A. Since the DC resistance of inductance affects the power efficiency, we recommend the inductance of low DC resistance. Besides, please take care so that the inductance peak current (Ipeak) does not exceed the maximum allowable current of inductor. 14-2. External Capacitor Type The external capacitors connected to the SM8172A should be multi-layer ceramic capacitors, with low temperature coefficient X5R or X7R class (EIA standard) multi-layer ceramic capacitors recommended. Use of high temperature coefficient Z5U or Y5V class multi-layer ceramic capacitors may cause an unstable output voltage condition and should be avoided. Capacitor temperature coefficient 3-letter codes (EIA standard) Lower category temperature Upper category temperature Maximum deviation in capacitance from +25°C (0V DC) value X = −55°C 5 = +85°C F = ± 7.5% Y = −30°C 6 = +105°C P = ± 10% Z = +10°C 7 = +125°C R = ± 15% 8 = +150°C S = ± 22% T = +22%/−33% U = +22%/−56% V = +22%/−82% Selection : X5R characteristics 14-3. VIN Supply Input Capacitor In some cases, the printed board component layout may affect the stability of the output voltages. In such cases, the VIN power supply capacitor should be increased or an additional capacitor connected. SEIKO NPC CORPORATION —14 SM8172A 14-4. Mounting The package rear surface is metallic, and can be connected to the printed circuit board pattern as a heatsink. The connected pattern should be tied to GND level. Furthermore, use of a thermal via structure on the PCB or other technology should be used to provide sufficient heat dissipation. Use a printed circuit board with 4 or more layers. The PCB wiring ratio*1 should exceed 200%, where the wiring ratio is the sum total of printed wiring pattern surface area relative to the circuit board surface area. *1: Determining the wiring pattern ratio Example: 4-layer board with the same wiring pattern on 4 layers (left), where the wiring pattern surface area on each layer is represented by S1, and the non-wired surface area is represented by S2. The wiring pattern is connected directly to the IC, and each layer’s wiring pattern is connected to the IC by through holes. The circuit board surface area seen from above is S1 + S2. First, calculate the board surface area, here represented by S1 + S2. Next, calculate the wiring pattern surface area on each layer connected to the IC, represented here by S1. Calculate the total wiring pattern surface area for all 4 layers, in this example 4 × S1. Finally, calculate the wiring ratio percentage using the following equation: (Wiring ratio) = (Total wiring pattern surface area connected to the IC) / (PCB surface area) × 100. In this example, 4 × S1/(S1 + S2) × 100 [%], or a wiring ratio of 200% when S1 = S2. S1 S2 SEIKO NPC CORPORATION —15 SM8172A 15. PACKAGE DIMENSION (Unit: mm) Top view Bottom view 2.50 ± 0.07 0.50 4 = 2.00 ± 0.05 1.25 A 1.64 6 6 10 1.34 0.40 ± 0.07 B 1.50 C0.25 1 2 5 0.10 S A B 0.10 S 0.05max 0.70 ± 0.05 0.75max 3.00 ± 0.07 10 5 2 1 0.22 ± 0.05 0.14 φ 0.05 M SAB S 0.05 S 0.5 SEIKO NPC CORPORATION —16 SM8172A Please pay your attention to the following points at time of using the products shown in this document. 1. The products shown in this document (hereinafter ”Products”) are designed and manufactured to the generally accepted standards of reliability as expected for use in general electronic and electrical equipment, such as personal equipment, machine tools and measurement equipment. The Products are not designed and manufactured to be used in any other special equipment requiring extremely high level of reliability and safety, such as aerospace equipment, nuclear power control equipment, medical equipment, transportation equipment, disaster prevention equipment, security equipment. The Products are not designed and manufactured to be used for the apparatus that exerts harmful influence on the human lives due to the defects, failure or malfunction of the Products. If you wish to use the Products in that apparatus, please contact our sales section in advance. In the event that the Products are used in such apparatus without our prior approval, we assume no responsibility whatsoever for any damages resulting from the use of that apparatus. 2. NPC reserves the right to change the specifications of the Products in order to improve the characteristics or reliability thereof. 3. The information described in this document is presented only as a guide for using the Products. No responsibility is assumed by us for any infringements of patents or other rights of the third parties which may result from its use. No license is granted by implication or otherwise under any patents or other rights of the third parties. Then, we assume no responsibility whatsoever for any damages resulting from that infringements. 4. The constant of each circuit shown in this document is described as an example, and it is not guaranteed about its value of the mass production products. 5. In the case of that the Products in this document falls under the foreign exchange and foreign trade control law or other applicable laws and regulations, approval of the export to be based on those laws and regulations are necessary. Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate government agencies. SEIKO NPC CORPORATION 1-9-9, Hatchobori, Chuo-ku, Tokyo 104-0032, Japan Telephone: +81-3-5541-6501 Facsimile: +81-3-5541-6510 http://www.npc.co.jp/ Email:[email protected] NC0804AE 2009.09 SEIKO NPC CORPORATION —17