Semiconductor Components Industries, LLC, 2003
June, 2003 - Rev. 3
1
Publication Order Number:
NCP5424/D
NCP5424
Dual Synchronous
Buck Controller with Input
Current Sharing
The NCP5424 is a flexible dual N-channel synchronous buck
controller utilizing V
2
TM
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 NCP5424 can also be configured as
two independent out-of-phase controllers.
Using the NCP5424 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 NCP5424 provides a cycle- to- cycle current limit on
Controller 2 allowing the system to handle transient overcurrent
events and a hiccup mode overcurrent protection on Controller 1
allowing lossless short circuit protection. In addition, the NCP5424
provides Soft Start, undervoltage lockout, and built-in adaptive FET
nonoverlap time to prevent shoot through.
Features
Hiccup Mode Current Limit (Controller 1)
Cycle-to-Cycle Current Limit (Controller 2)
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
NCP5424DR2
A
= Assembly Location
WL = Wafer Lot
Y
= Year
WW = Work Week
Device
Package
Shipping
ORDERING INFORMATION
NCP5424D
SO-16
48 Units/Rail
SO-16
2500 Tape & Reel
V
FB1
COMP1
IS+1
GATE(H)1
PIN CONNECTIONS AND
MARKING DIAGRAM
GATE(L)1
GND
BST
IS-
SO-16
D SUFFIX
CASE 751B
1
16
GATE(H)2
GATE(L)2
V
CC
R
OSC
IS+2
V
FB+2
V
FB- 2
COMP2
A
W
L
YWW
NCP5424
16
1
http://onsemi.com
NCP5424
http://onsemi.com
2
Figure 1. Two-Phase Buck Regulator Application, with Input Current Sharing
C11
1.0
F
L2
1.3
H/15 A
GATE(H)1
GATE(L)1
GATE(H)2
GATE(L)2
NCP5424
V
CC
BST
GND
Q3
Q4
IS+1
IS-
COMP1
V
FB1
IS+2
V
FB+2
COMP2
V
FB- 2
R
OSC
MTD60N03
MTD90N02
+
C3/4/5
680
F/
4 V
R5
5 k
1%
C8
.22
F
R6
10 k
1%
C14
0.1
F
C13
0.01
F
R12
30.9 k
Q1
Q2
MTD60N03
MTD90N02
L1
1.3
H/15 A
+
C19/20/21
680
F/
4 V
12 V
U1
+
+
C17
220
F
C18
220
F
3.3 V
R3
x k
1%
R4
x k
1%
R2
x k
R1
x k
C6
0.1
F
+
C2
220
F
C1
220
F
R17
4 k
5.0 V
+
1.5 V @ 20 A
NCP5424
http://onsemi.com
3
MAXIMUM RATINGS*
Rating
Value
Unit
Operating Junction Temperature, T
J
150
C
Storage Temperature Range, T
S
-65 to +150
C
ESD Susceptibility (Human Body Model)
2.0
kV
Package Thermal Resistance, SO-16:
Junction-to-Case, R
JC
Junction-to-Ambient, R
JA
28
115
C/W
C/W
Lead Temperature Soldering:
Reflow: (SMD styles only) (Note 1)
230 peak
C
1. 60 second maximum above 183
C.
*The maximum package power dissipation must be observed.
MAXIMUM RATINGS
Pin Symbol
Pin Name
V
MAX
V
MIN
I
SOURCE
I
SINK
V
CC
IC Power Input
16 V
-0.3 V
N/A
1.5 A peak
200 mA DC
COMP1, COMP2
Compensation Capacitor for
Channel 1 or 2
4.0 V
-0.3 V
1.0 mA
3.5 mA
V
FB1
, V
FB+2
, V
FB- 2
Voltage Feedback Input for
Channel 1 or 2
5.0 V
-0.3 V
1.0 mA
1.0 mA
BST
Power Input for GATE(H)1, 2
20 V
-0.3 V
N/A
1.5 A peak
200 mA DC
R
OSC
Oscillator Resistor
4.0 V
-0.3 V
1.0 mA
1.0 mA
GATE(H)1
,
GATE(H)2
High-Side FET Driver
for Channel 1 or 2
20 V
-0.3 V
1.5 A peak
200 mA DC
1.5 A peak
200 mA DC
GATE(L)1
,
GATE(L)2
Low-Side FET Driver for
Channel 1 or 2
16 V
-0.3 V
1.5 A peak
200 mA DC
1.5 A peak
200 mA DC
GND
Ground
0 V
0 V
1.5 A peak
200 mA DC
N/A
IS+1, IS+2
Positive Current Sense for
Channel 1 or 2
6.0 V
-0.3 V
1.0 mA
1.0 mA
IS-
Negative Current Sense for
Channels 1 and 2
6.0 V
-0.3 V
1.0 mA
1.0 mA
NCP5424
http://onsemi.com
4
ELECTRICAL CHARACTERISTICS
(0
C < T
A
< 70
C; 0
C < T
J
< 125
C; R
OSC
= 30.9 k, C
COMP1,2
= 0.1
F,
10.8
V < V
CC
< 13.2
V;
10.8
V < BST
< 20
V, C
GATE(H)1,2
=
C
GATE(L)1,2
= 1.0
nF, V
FB+2
= 1.0 V; unless otherwise specified.)
Characteristic
Test Conditions
Min
Typ
Max
Unit
Error Amplifier
V
FB
Bias Current
V
FBX
= 0 V
-
0.5
1.6
A
V
FB1(2)
Input Range
Note 2
0
-
1.1
V
COMP1,2 Source Current
COMP1,2 = 1.2 V to 2.5 V; V
FB1(- 2)
= 0.8 V
15
30
60
A
COMP1,2 Sink Current
COMP1,2 = 1.2 V; V
FB1(- 2)
= 1.2 V
15
30
60
A
Reference Voltage 1(2)
COMP1 = V
FB1
; COMP2 = V
FB- 2
0.980
1.000
1.020
V
COMP1,2 Max Voltage
V
FB1(- 2)
= 0.8 V
3.0
3.3
-
V
COMP1,2 Min Voltage
V
FB1(- 2)
= 1.2 V
-
0.25
0.35
V
Open Loop Gain
-
-
95
-
dB
Unity Gain Band Width
-
-
40
-
kHz
PSRR @ 1.0 kHz
-
-
70
-
dB
Transconductance
-
-
32
-
mmho
Output Impedance
-
-
2.5
-
M
Input Offset, Error Amp. 2
-
-3.0
0
3.0
mV
Error Amp. 2 Common Mode Range
Note 2
1.75
2.0
-
V
GATE(H) and GATE(L)
High Voltage (AC)
Measure: V
CC
- GATE(L)1,2;
BST - GATE(H)1,2; Note 2
-
0
0.5
V
Low Voltage (AC)
Measure:GATE(L)1,2 or GATE(H)1,2; Note 2
-
0
0.5
V
Rise Time
1.0 V < GATE(L)1,2 < V
CC
- 1.0 V
1.0 V < GATE(H)1,2 < BST - 1.0 V,
BST
14 V
-
20
50
ns
Fall Time
V
CC
- 1.0 > GATE(L)1,2 > 1.0 V
BST - 1.0 > GATE(H)1,2 > 1.0 V,
BST
14 V
-
15
50
ns
GATE(H) to GATE(L) Delay
GATE(H)1,2 < 2.0 V, GATE(L)1,2 > 2.0 V
BST
14 V
20
40
70
ns
GATE(L) to GATE(H) Delay
GATE(L)1,2 < 2.0 V, GATE(H)1,2 > 2.0 V;
BST
14 V
20
40
70
ns
GATE(H)1(2) and GATE(L)1(2)
pull-down.
Resistance to GND
Note 2
50
125
280
k
PWM Comparator
PWM Comparator Offset
V
FB1(- 2)
= 0 V; Increase COMP1,2 until
GATE(H)1,2 starts switching
0.30
0.40
0.50
V
Artificial Ramp
Duty cycle = 50%, Note 2
60
105
150
mV
Minimum Pulse Width
Note 2
-
-
300
ns
2. Guaranteed by design, not 100% tested in production.
NCP5424
http://onsemi.com
5
ELECTRICAL CHARACTERISTICS (continued)
(0
C < T
A
< 70
C; 0
C < T
J
< 125
C; R
OSC
= 30.9 k, C
COMP1,2
= 0.1
F,
10.8
V < V
CC
< 13.2
V;
10.8
V < BST
< 20
V, C
GATE(H)1,2
=
C
GATE(L)1,2
= 1.0
nF, V
FB+2
= 1.0 V; unless otherwise specified.)
Characteristic
Unit
Max
Typ
Min
Test Conditions
Oscillator
Switching Frequency
R
OSC
= 61.9 k; Measure GATE(H)1; Note 3
112
150
188
kHz
Switching Frequency
R
OSC
= 30.9 k; Measure GATE(H)1
250
300
350
kHz
Switching Frequency
R
OSC
= 15.1 k; Measure GATE(H)1; Note 3
450
600
750
kHz
R
OSC
Voltage
R
OSC
= 30.9 k, Note 3
0.970
1.000
1.030
V
Phase Difference
-
-
180
-
Supply Currents
V
CC
Current
COMP1,2 = 0 V (No Switching)
-
13
17
mA
BST Current
COMP1,2 = 0 V (No Switching)
-
3.5
6.0
mA
Undervoltage Lockout
Start Threshold
GATE(H) Switching; COMP1,2 charging
7.8
8.6
9.4
V
Stop Threshold
GATE(H) not switching; COMP1,2 discharging
7.0
7.8
8.6
V
Hysteresis
Start-Stop
0.5
0.8
1.5
V
Hiccup Mode Overcurrent Protection (Controller 1)
OVC Comparator Offset Voltage
0 V < IS+ 1 < 5.5 V, 0 V < IS- < 5.5 V
55
70
85
mV
Discharge Threshold
-
0.20
0.25
0.30
V
IS+ 1 Bias Current
0 V < IS+ 1 < 5.5 V
-1.0
0.1
1.0
A
IS- Bias Current
0 V < IS- < 5.5 V
-2.0
0.2
2.0
A
OVC Common Mode Range
-
0
-
5.5
V
OVC Latch COMP1 Discharge Current
COMP1 = 1.0 V
2.0
5.0
8.0
A
Cycle-to-Cycle Current Limit (Controller 2)
OVC Comparator Offset Voltage
0 V < IS+ 2 < 5.5 V, 0 V < IS- < 5.5 V
55
70
85
mV
IS+ 2 Bias Current
0 V < IS+ 2 < 5.5 V
-1.0
0.1
1.0
A
OVC Common Mode Range
-
0
-
5.5
V
OVC Latch COMP2 Discharge Current
COMP = 1.0 V
0.3
1.2
3.5
mA
3. Guaranteed by design, not 100% tested in production.
PDF 
ZIP