FAN5234QSCX_NL Fairchild Semiconductor, FAN5234QSCX_NL Datasheet

Page 1

FAN5234 Mobile-Friendly PWM/PFM Controller Features • Wide input voltage range (2 to 24V) for Mobile systems • Excellent dynamic response with Voltage Feed-Forward and Average Current Mode control • Lossless current sensing on low-side MOSFET or precision over-current using sense ...

Page 2

FAN5234 Pin Configurations Pin Definitions Pin Number Pin Name 1 VIN Input Voltage. Connect to main input power source (battery). Also used to program operating frequency for low input voltage operation. See Table 1. 2 PGOOD Power Good Flag. An ...

Page 3

FAN5234 Absolute Maximum Ratings Absolute maximum ratings are the values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied. Parameter VCC Supply Voltage: VIN BOOT, SW, ISNS, HDRV ...

Page 4

PRODUCT SPECIFICATION Electrical Specifications Parameter Power Supplies VCC Current VIN Current - Sinking VIN Current - Sourcing VIN Current - Shut-down UVLO Threshold Oscillator Frequency Ramp Amplitude, pk–pk Ramp Amplitude, pk–pk Ramp Offset Ramp / VIN Gain Ramp / VIN ...

Page 5

FAN5234 EN FPWM HYST SS OVP RAMP OSC VIN CLK VSEN EA SS VREF Reference and PGOOD Soft Start REF2 Circuit Description Overview The FAN5234 is a PWM controller intended for low voltage power applications in modern notebook, desktop, and ...

Page 6

PRODUCT SPECIFICATION The voltage at the positive input of the error amplifier is lim- ited by the voltage at the SS pin which is charged with a 5mA current source. Once C has charged to VREF (0.9V) SS the output ...

Page 7

FAN5234 The hysteretic comparator causes HDRV turn-on when the output voltage (at VSEN) falls below the lower threshold (10mV below VREF) and terminates the PFM signal when VSEN rises over the higher threshold (5mV above VREF). The switching frequency is ...

Page 8

PRODUCT SPECIFICATION LDRV R SENSE ISNS PGND Figure 5. Improving current sensing accuracy More accurate sensing can be achieved by using a resistor (R1) instead of the R of the FET as shown in Figure 5. DS(ON) This approach causes ...

Page 9

FAN5234 This region is also associated with phase ‘bump’ or reduced phase shift. The amount of phase shift reduction depends the width of the region of flat gain and has a maximum value of 90 degrees. To further simplify the ...

Page 10

PRODUCT SPECIFICATION Setting the Output Voltage The internal reference is 0.9V. The output is divided down by a voltage divider to the VSEN pin (for example, R1 and R2 in Figure 1). The output voltage therefore is: V – 0.9V ...

Page 11

FAN5234 Assuming switching losses are about the same for both the rising edge and falling edge, Q1's switching losses, occur during the shaded time when the MOSFET has voltage across it and current through it. These losses are given by: ...

Page 12

PRODUCT SPECIFICATION Table 2. BOM For 1.8V, 3.5A regulator (Figure 1) Description Capacitor 68µF, Tantalum, 25V, ESR 95mΩ Capacitor 10nF, Ceramic Capacitor 68µF, Tantalum, 6V, ESR 1.8Ω Capacitor 0.1µF, Ceramic Capacitor 330µF, Tantalum, 6V, ESR 100mΩ 1.82KΩ, 1% Resistor 1.3KΩ, ...

Page 13

FAN5234 Mechanical Dimensions 16-Pin QSOP Inches Millimeters Symbol Min. Max. Min. A .053 .069 1.35 A1 .004 .010 0.10 B .008 .012 0.20 C .007 .010 0.18 D .189 .197 4.80 E .150 .157 3.81 .025 BSC 0.63 BSC e ...

Page 14

PRODUCT SPECIFICATION Mechanical Dimensions 16-Pin TSSOP DIMENSIONS METRIC ONLY 5.0 ± 0.1 -A- 16 6.4 3.2 1 PIN #1 IDENT. 0.1 C ALL LEAD TIPS -C- 0.65 TYP 14 (1.78 TYP) 0.42 TYP 8 LAND PATTERN RECOMMENDATION 4.4 ± 0.1 ...

Page 15

... NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems ...