FAN5234QSCX_NL

Manufacturer Part NumberFAN5234QSCX_NL
ManufacturerFairchild Semiconductor
FAN5234QSCX_NL datasheet
 


Specifications of FAN5234QSCX_NL

Dc To Dc Converter TypeSynchronous Buck Controller/PWM DC to DC ControllerNumber Of Outputs1
Pin Count16Input Voltage5 to 24V
Output Voltage0.9 to 5.5VPackage TypeQSOP
MountingSurface MountOperating Temperature ClassificationCommercial
Operating Temperature (min)-10COperating Temperature (max)85C
Lead Free Status / Rohs StatusCompliant  
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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 resistor
• VCC Under-voltage Lockout
• Power-Good Signal
• Light load Hysteretic mode maximizes efficiency
• QSOP16, TSSOP16
• 300Khz or 600Khz operation
Applications
• Mobile PC regulator
• Hand-Held PC power
Typical Application
VIN (BATTERY)
= 2 to 24V
VCC
+5
C4
R5
ILIM
EN
SS1
C3
+5
FPWM
R4
AGND
PGOOD
Figure 1. 1.8V Output Regulator (see Table 2, page 12 for BOM)
General Description
The FAN5234 PWM controller provides high efficiency and
regulation with an adjustable output from 0.9V to 5.5V that
are required to power I/O, chip-sets, memory banks or
peripherals in high-performance notebook computers, PDAs
and Internet appliances. Synchronous rectification and
hysteretic operation at light loads contribute to a high
efficiency over a wide range of loads. The hysteretic mode of
operation can be disabled if PWM mode is desired for all
load levels. Efficiency is even further enhanced by using
MOSFET’s R
DS(ON)
Feed-forward ramp modulation, average current mode
control, and internal feedback compensation provide fast
response to load transients. The FAN5234 monitors these
outputs and generates a PGOOD (power good) signal when
the soft-start is completed and the output is within ±10% of
its set point. A built-in over-voltage protection prevents the
output voltage from going above 120% of the set point.
Normal operation is automatically restored when the over-
voltage conditions go away. Under-voltage protection latches
the chip off when the output drops below 75% of its set value
after the soft-start sequence is completed. An adjustable
over-current function monitors the output current by sensing
the voltage drop across the lower MOSFET.
VIN
C1
1
BOOT
11
15
Q1A
FAN5234
C5
HDRV
14
L1
SW
4
13
Q1B
3
R3
LDRV
10
7
PGND
9
16
ISNS
12
8
VSEN
6
2
VOUT
5
www.fairchildsemi.com
as a current sense component.
C2
D1
+5
1.8V@3.5A
C6
R1
R2
REV. 1.0.10 5/3/04

FAN5234QSCX_NL Summary of contents

  • 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 ...