Document
NCP5424A
Dual Synchronous Buck Controller with Input Current Sharing
The NCP5424A is a flexible dual N−channel synchronous buck controller utilizing V2™ control for fast transient response and excellent line and load regulation. This highly versatile controller can be configured as a single two phase output converter that draws programmable amounts of current from two different input voltages or all current from one supply. The NCP5424A can also be configured as two independent out−of−phase controllers.
Using the NCP5424A in a current sharing input configuration is ideal for applications where more power is required than is available from one supply, such as video cards or other plug−in boards. When configured as a dual output controller, the output of one controller can be divided down and used as the reference for the second controller. This tracking capability is useful in applications such as Double Data Rate (DDR) Memory power where the termination voltage must track VDD.
The NCP5424A provides a cycle−to−cycle current limit allowing the system to handle transient overcurrent events. In addition, the NCP5424A provides Soft Start, undervoltage lockout, and built−in adaptive FET nonoverlap time to prevent shoot through.
Features
• Cycle−to−Cycle Current Limit • Programmable Soft Start • 100% Duty Cycle for Enhanced Transient Response • 150 kHz to 600 kHz Programmable Frequency Operation • Switching Frequency Set by Single Resistor • Out−Of−Phase Synchronization Between the Channels Reduces the
Input Filter Requirement
• Undervoltage Lockout
Applications
• Video Graphics Card • DDR Memory • High Current (Two−Phase) Power Supplies • Dual Output DC−DC Converters
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16 1
SO−16 D SUFFIX CASE 751B
PIN CONNECTIONS AND MARKING DIAGRAM
1 GATE(H)1
GATE(L)1
GND BST
IS+1
IS− VFB1 COMP1
NCP5424A AWLYWW
16 GATE(H)2
GATE(L)2
VCC ROSC IS+2
VFB+2 VFB−2 COMP2
A = Assembly Location WL = Wafer Lot Y = Year WW = Work Week
ORDERING INFORMATION
Device NCP5424AD NCP5424ADR2
Package SO−16 SO−16
Shipping 48 Units/Rail 2500 Tape & Reel
© Semiconductor Components Industries, LLC, 2003
August, 2003 − Rev. 0
1
Publication Order Number: NCP5424A/D
12 V
5.0 V
+ C2
+ C1
220 µF 220 µF
NCP5424A
+ C17 220 µF
3.3 V
+ C18 220 µF
C6
0.1 µF
R1 R2 xk xk
L2 + C3/4/5 1.3 µH/15 A
680 µF/ 4V
Q3 MTD60N03
Q4 MTD90N02
R3 x k ± 1%
R4 x k ± 1%
R5 5 k ± 1%
C8 .22 µF
R6 10 k ± 1%
C11
1.0 µF
U1 VCC
BST
GATE(H)1 GATE(H)2
GATE(L)1 GATE(L)2
IS+1
IS+2
NCP5424A
IS− VFB+2
COMP1
COMP2
VFB1
GND
VFB−2
ROSC R12
30.9 k
Q1 MTD60N03
L1
1.3 µH/15 A Q2
MTD90N02 R17
4k C14 0.1 µF
C19/20/21 + 680 µF/
4V
C13 0.01 µF
1.5 V @ 20 A Figure 1. Two−Phase Buck Regulator Application, with Input Current Sharing
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NCP5424A
MAXIMUM RATINGS*
Rating
Operating Junction Temperature, TJ Storage Temperature Range, TS ESD Susceptibility (Human Body Model)
Package Thermal Resistance, SO−16:
Junction−to−Case, RθJC Junction−to−Ambient, RθJA
Lead Temperature Soldering:
1. 60 second maximum above 183°C. *The maximum package power dissipation must be observed.
Reflow: (SMD styles only) (Note 1)
Value 150 −65 to +150 2.0 28 115
230 peak
Unit °C °C kV °C/W °C/W °C
MAXIMUM RATINGS Pin Symbol VCC
COMP1, COMP2
VFB1, VFB+2, VFB−2 BST
ROSC GATE(H)1, GATE(H)2 GATE(L)1, GATE(L)2
GND
IS+1, IS+2
IS−
Pin Name IC Power Input
Compensation Capacitor for Channel 1 or 2
Voltage Feedback Input for Channel 1 or 2
Power Input for GATE(H)1, 2
Oscillator Resistor High−Side FET Driver
for Channel 1 or 2 Low−Side FET Driver for
Channel 1 or 2 Ground
Positive Current Sense for Channel 1 or 2
Negative Current Sense for Channels 1 and 2
VMAX 16 V 4.0 V 5.0 V 20 V 4.0 V 20 V 16 V 0V 6.0 V 6.0 V
VMIN −0.3 V −0.3 V −0.3 V −0.3 V −0.3 V −0.3 V −0.3 V
0V −0.3 V −0.3 V
ISOURCE N/A
1.0 mA
1.0 mA
N/A
1.0 mA 1.5 A peak 200 mA DC 1.5 A peak 200 mA DC 1.5 A peak 200 mA DC
1.0 mA
1.0 mA
ISINK 1.5 A peak 200 mA DC
3.5 mA
1.0 mA
1.5 A peak 200 mA DC
1.0 mA 1.5 A peak 200 mA DC 1.5 A peak 200 mA DC
N/A
1.0 mA
1.0 mA
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NCP5424A
ELECTRICAL CHARACTERISTICS (0°C < TA < 70°C; 0°C < TJ < 125°C; ROSC = 30.9 k, CCOMP1,2 = 0.1 µF, 10.8 V < VCC < 13.2 V; 10.8 V < BST < 20 V, CGATE(H)1,2 = CGATE(L)1,2 = 1.0 nF, VFB+2 = 1.0 V; unless otherwise specified.)
Characteristic
Test Conditions
Min Typ Max
Error Amplifier
VFB Bias Current VFB1(2) Input Range COMP1,2 Source Current COMP1,2 Sink Current Reference Voltage 1(2) COMP1,2 Max Voltage COMP1,2 Min Voltage Open Loop Gain
VFBX = 0 V Note 2 COMP1,2 = 1.2 V to 2.5 V; VFB1(−2) = 0.8 V COMP1,2 = 1.2 V; VFB1(−2) = 1.2 V COMP1 = VFB1; COMP2 = VFB−2 VFB1(−2) = 0.8 V VFB1(−2) = 1.2 V
−
− 0 15 15 0.980 3.0 − −
0.5 − 30 30 1.000 3.3 0.25 95
1.6 1.1 60 60 1.020 − 0.35 −
Unity Gain Band Width
− − 40 −
PSRR @ 1.0 kHz
− − 70 −
Transconductance
− − 32 −
Output Impedance
− − 2.5 −
Input Offset, Error Amp. 2
−
−3.0 0
3.0
Error Amp. 2 Common Mode Range
Note 2
1.75 2.0
−
GATE(H).