CS51411EMNR2G [ONSEMI]

1.5 A, 260 kHz and 520 kHz, Low Voltage Buck Regulators with External Bias or Synchronization Capability; 1.5 A , 260 kHz和520 kHz的低电压降压稳压器,外部偏置或同步功能
CS51411EMNR2G
型号: CS51411EMNR2G
厂家: ONSEMI    ONSEMI
描述:

1.5 A, 260 kHz and 520 kHz, Low Voltage Buck Regulators with External Bias or Synchronization Capability
1.5 A , 260 kHz和520 kHz的低电压降压稳压器,外部偏置或同步功能

稳压器
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中文:  中文翻译
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CS51411, CS51412,  
CS51413, CS51414  
1.5 A, 260 kHz and 520 kHz,  
Low Voltage Buck  
Regulators with External  
Bias or Synchronization  
Capability  
http://onsemi.com  
MARKING DIAGRAMS  
The CS5141X products are 1.5 A buck regulator ICs. These devices  
are fixed−frequency operating at 260 kHz and 520 kHz. The regulators  
use the V control architecture to provide unmatched transient  
response, the best overall regulation and the simplest loop  
compensation for today’s high−speed logic. These products  
accommodate input voltages from 4.5 V to 40 V.  
8
8
5141x  
ALYWy  
G
2
1
SOIC−8  
D SUFFIX  
CASE 751  
1
The CS51411 and CS51413 contain synchronization circuitry. The  
CS51412 and CS51414 have the option of powering the controller  
from an external 3.3 V to 6.0 V supply in order to improve efficiency,  
especially in high input voltage, light load conditions.  
The on−chip NPN transistor is capable of providing a minimum of  
1.5 A of output current, and is biased by an external “boost” capacitor  
to ensure saturation, thus minimizing on−chip power dissipation.  
Protection circuitry includes thermal shutdown, cycle−by−cycle  
current limiting and frequency foldback. The CS51411 and CS51413  
are functionally pin−compatible with the LT1375. The CS51412 and  
CS51414 are functionally pin−compatible with the LT1376.  
1
18  
18  
CS5141xy  
AWLYYWW G  
G
1
18−LEAD DFN  
MN SUFFIX  
CASE 505  
5141x = Device Code  
x = 1, 2, 3 or 4  
A
= Assembly Location  
Features  
L, WL = Wafer Lot  
Y, YY = Year  
W, WW = Work Week  
y = E or G  
G
2
V Architecture Provides Ultrafast Transient Response, Improved  
Regulation and Simplified Design  
2.0% Error Amp Reference Voltage Tolerance  
Switch Frequency Decrease of 4:1 in Short Circuit Conditions  
Reduces Short Circuit Power Dissipation  
BOOST Lead Allows “Bootstrapped” Operation to Maximize  
Efficiency  
= Pb−Free Package  
ORDERING INFORMATION  
See detailed ordering and shipping information in the package  
dimensions section on page 18 of this data sheet.  
Sync Function for Parallel Supply Operation or Noise Minimization  
Shutdown Lead Provides Power−Down Option  
85 mA Quiescent Current During Power−Down  
Thermal Shutdown  
Soft−Start  
Pin−Compatible with LT1375 and LT1376  
Pb−Free Packages are Available  
© Semiconductor Components Industries, LLC, 2007  
1
Publication Order Number:  
February, 2007 − Rev. 17  
CS51411/D  
CS51411, CS51412, CS51413, CS51414  
PIN CONNECTIONS  
CS51411/3  
CS51411/3  
CS51412/4  
1
8
BOOST  
V
V
C
BOOST  
1
2
3
4
5
6
7
8
9
18  
17  
16  
15  
14  
13  
12  
11  
10  
NC  
BOOST  
1
2
3
4
5
6
7
8
9
18  
NC  
V
IN  
FB  
V
IN  
V
IN  
V
IN  
V
V
V
IN  
V
IN  
V
IN  
17  
16  
15  
14  
13  
12  
11  
10  
V
V
C
C
V
SW  
GND  
FB  
FB  
SHDNB  
SYNC  
NC  
NC  
GND  
NC  
NC  
NC  
NC  
GND  
NC  
NC  
Vsw  
Vsw  
V
V
V
V
SW  
SW  
CS51412/4  
SW  
SW  
1
8
SHDNB  
NC  
BIAS  
NC  
BOOST  
V
V
C
SYNC  
SHDNB  
V
IN  
FB  
V
SW  
GND  
BIAS  
SHDNB  
PACKAGE PIN DESCRIPTION  
SOIC−8  
DFN18  
Package Pin #  
Package Pin #  
Pin Symbol  
Function  
1
1
BOOST  
The BOOST pin provides additional drive voltage to the on−chip NPN  
power transistor. The resulting decrease in switch on voltage increases  
efficiency.  
2
3
2, 3, 4  
5, 6, 7  
V
This pin is the main power input to the IC.  
IN  
V
SW  
This is the connection to the emitter of the on−chip NPN power transistor  
and serves as the switch output to the inductor. This pin may be  
subjected to negative voltages during switch off−time. A catch diode is  
required to clamp the pin voltage in normal operation. This node can  
stand −1.0 V for less than 50 ns during switch node flyback.  
4
8
BIAS  
The BIAS pin connects to the on−chip power rail and allows the IC to run  
most of its internal circuitry from the regulated output or another low  
voltage supply to improve efficiency. The BIAS pin is left floating if this  
feature is not used.  
(CS51412/CS51414)  
5
This pin provides the synchronization input.  
(CS51411/CS51413)  
10  
10  
SYNC  
5
SHDNB  
The shutdown pin is active low and TTL compatible. The IC goes into  
sleep mode, drawing less than 85 mA when the pin voltage is pulled  
below 1.0 V. This pin should be left floating in normal position.  
(CS51412/CS51414) (CS51412/CS51414)  
4
8
(CS51411/CS51413) (CS51411/CS51413)  
6
7
13  
16  
GND  
Power return connection for the IC.  
V
FB  
The FB pin provides input to the inverting input of the error amplifier. If  
V
FB  
is lower than 0.29 V, the oscillator frequency is divided by four, and  
current limit folds back to about 1 A. These features protect the IC under  
severe overcurrent or short circuit conditions.  
8
17  
V
The V pin provides a connection point to the output of the error  
C
C
amplifier and input to the PWM comparator. Driving of this pin should be  
avoided because on−chip test circuitry becomes active whenever  
current exceeding 0.5 mA is forced into the IC.  
9, 11, 12, 14, 15, 18  
NC  
No Connection  
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2
CS51411, CS51412, CS51413, CS51414  
PRODUCT SELECTION GUIDE  
Part Number  
CS51411E  
Frequency  
260 kHz  
260 kHz  
260 kHz  
260 kHz  
520 kHz  
520 kHz  
520 kHz  
520 kHz  
Temperature Range  
−40°C to 85°C  
0°C to 70°C  
Bias/Sync  
Sync  
Sync  
Bias  
CS51411G  
CS51412E  
−40°C to 85°C  
0°C to 70°C  
CS51412G  
Bias  
CS51413E  
−40°C to 85°C  
0°C to 70°C  
Sync  
Sync  
Bias  
CS51413G  
CS51414E  
−40°C to 85°C  
0°C to 70°C  
CS51414G  
Bias  
1N4148  
D1  
C1  
4.5 V − 16 V  
0.1 mF  
C2  
100 mF  
1
U1  
2
3
V
3.3 V  
BOOST  
IN  
V
SW  
L1  
15 mH  
4
5
Shutdown  
SYNC  
SHDNB  
CS51411/3  
R1  
205  
C3  
D3  
1N5821  
SYNC  
100 mF  
V
C
GND  
V
7
FB  
8
6
R2  
127  
C4  
0.1 mF  
Figure 1. Application Diagram, 4.5 V − 16 V to 3.3 V @ 1.0 A Converter  
MAXIMUM RATINGS  
Rating  
Value  
Unit  
Operating Junction Temperature Range, T  
Lead Temperature Soldering:  
−40 to 150  
230 peak  
−65 to +150  
2.0  
°C  
°C  
°C  
kV  
J
Reflow: (SMD styles only) (Note 1)  
Storage Temperature Range, T  
S
ESD Damage Threshold (Human Body Model)  
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the  
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect  
device reliability.  
1. 60 second maximum above 183°C.  
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3
 
CS51411, CS51412, CS51413, CS51414  
MAXIMUM RATINGS  
Pin Name  
V
Max  
V
MIN  
I
I
SINK  
SOURCE  
V
40 V  
40 V  
40 V  
7.0 V  
7.0 V  
7.0 V  
7.0 V  
7.0 V  
7.0 V  
−0.3 V  
−0.3 V  
N/A  
4.0 A  
100 mA  
10 mA  
1.0 mA  
1.0 mA  
1.0 mA  
50 mA  
1.0 mA  
1.0 mA  
IN  
BOOST  
N/A  
V
SW  
−0.6 V/−1.0 V, t < 50 ns  
−0.3 V  
4.0 A  
V
1.0 mA  
1.0 mA  
1.0 mA  
1.0 mA  
1.0 mA  
50 mA  
C
SHDNB  
SYNC  
BIAS  
−0.3 V  
−0.3 V  
−0.3 V  
V
FB  
−0.3 V  
GND  
−0.3 V  
ELECTRICAL CHARACTERISTICS (−40°C < T < 125°C (CS51411E/2E/3E/4E); −40°C < T < 85°C (CS51411E/2E/3E/4E);  
J
A
0°C < T < 70°C (CS51411G/2G/3G/4G), 4.5 V< V < 40 V; unless otherwise specified.)  
A
IN  
Characteristic  
Test Conditions  
Min  
Typ  
Max  
Unit  
Oscillator  
Operating Frequency  
Operating Frequency  
Frequency Line Regulation  
Maximum Duty Cycle  
CS51411/CS51412  
CS51413/CS51414  
224  
446  
260  
520  
0.05  
90  
296  
594  
0.15  
95  
kHz  
kHz  
%/V  
%
85  
V
FB  
Frequency Foldback Threshold  
0.29  
0.32  
0.36  
V
PWM Comparator  
Slope Compensation Voltage  
CS51411/CS51412, Fix V DV /DT  
ON  
CS51413/CS51414  
8.0  
25  
17  
50  
26  
75  
mV/ms  
mV/ms  
FB,  
C
Minimum Output Pulse Width  
CS51411/CS51412, V to V  
150  
300  
230  
ns  
ns  
FB  
SW  
CS51413/CS51414, V to V  
FB  
SW  
Power Switch  
Current Limit  
V
V
> 0.36 V  
< 0.29 V  
= 1.5 A, V  
1.6  
0.9  
0.4  
2.3  
1.5  
0.7  
120  
3.0  
2.1  
1.0  
160  
A
A
FB  
Foldback Current  
Saturation Voltage  
Current Limit Delay  
FB  
I
= V + 2.5 V  
V
OUT  
BOOST  
IN  
(Note 2)  
ns  
Error Amplifier  
Internal Reference Voltage  
Reference PSRR  
1.244  
1.270  
40  
1.296  
V
dB  
(Note 2)  
FB Input Bias Current  
Output Source Current  
Output Sink Current  
Output High Voltage  
Output Low Voltage  
0.02  
25  
0.1  
35  
35  
1.53  
60  
mA  
V
V
V
V
= 1.270 V, V = 1.0 V  
15  
15  
1.39  
5.0  
mA  
C
FB  
= 1.270 V, V = 2.0 V  
25  
mA  
C
FB  
= 1.0 V  
= 2.0 V  
1.46  
20  
V
FB  
FB  
mV  
kHz  
dB  
Unity Gain Bandwidth  
Open Loop Amplifier Gain  
Amplifier Transconductance  
(Note 2)  
(Note 2)  
(Note 2)  
500  
70  
6.4  
mA/V  
2. Guaranteed by design, not 100% tested in production.  
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4
 
CS51411, CS51412, CS51413, CS51414  
ELECTRICAL CHARACTERISTICS (−40°C < T < 125°C (CS51411E/2E/3E/4E); −40°C < T < 85°C (CS51411E/2E/3E/4E);  
J
A
0°C < T < 70°C (CS51411G/2G/3G/4G), 4.5 V< V < 40 V; unless otherwise specified.)  
A
IN  
Characteristic  
Test Conditions  
Min  
Typ  
Max  
Unit  
Sync  
Sync Frequency Range  
Sync Frequency Range  
Sync Pin Bias Current  
CS51411/CS51412  
CS51413/CS51414  
305  
575  
470  
880  
kHz  
kHz  
V
SYNC  
V
SYNC  
= 0 V  
= 5.0 V  
250  
0.1  
360  
0.2  
460  
mA  
mA  
Sync Threshold Voltage  
1.0  
1.5  
1.9  
V
Shutdown  
Shutdown Threshold Voltage  
Shutdown Pin Bias Current  
1.0  
1.3  
1.6  
35  
V
V
= 0 V  
0.14  
5.00  
mA  
SHDNB  
Thermal Shutdown  
Overtemperature Trip Point  
Thermal Shutdown Hysteresis  
General  
(Note 3)  
(Note 3)  
175  
185  
42  
195  
°C  
°C  
Quiescent Current  
I
= 0 A  
3.0  
8.0  
6.0  
4.0  
20  
15  
6.25  
85  
mA  
mA  
SW  
Shutdown Quiescent Current  
Boost Operating Current  
Minimum Boost Voltage  
Startup Voltage  
V
= 0 V  
SHDNB  
BOOST  
V
− V  
= 2.5 V  
40  
mA/A  
V
SW  
(Note 3)  
2.5  
4.4  
12  
2.2  
3.3  
7.0  
V
Minimum Output Current  
mA  
3. Guaranteed by design, not 100% tested in production.  
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5
 
CS51411, CS51412, CS51413, CS51414  
SHDNB  
SYNC  
V
IN  
5.0 mA  
Shutdown  
Comparator  
2.9 V LDO  
Voltage  
Regulator  
+
Thermal  
Shutdown  
Artificial  
Ramp  
Oscillator  
BIAS  
BOOST  
+
1.3 V  
Output  
Driver  
S
R
Q
V
SW  
+
Current  
Limit  
Comparator  
+
PWM  
Comparator  
I
REF  
1.46 V  
+
V
FB  
I
FOLDBACK  
+
Frequency  
+
GND  
0.32 V  
and Current  
Limit Foldback  
+
1.270 V  
Error  
Amplifier  
V
C
Figure 2. Block Diagram  
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6
CS51411, CS51412, CS51413, CS51414  
APPLICATIONS INFORMATION  
THEORY OF OPERATION  
cycle modulation to occur. Actual oscilloscope waveforms  
taken from the converter show the switch node V  
V2 Control  
,
SWITCH  
the error signal V and the feedback signal V (AC  
component only) are shown in Figure 5.  
C
FB  
The CS5141X family of buck regulators utilizes a V2  
control technique and provides a high level of integration to  
enable high power density design optimization.  
Every pulse width modulated controller configures basic  
control elements such that when connected to the feedback  
signal of a power converter, sufficient loop gain and  
bandwidth is available to regulate the voltage set point  
against line and load variations. The arrangement of these  
elements differentiates a voltage mode, or a current mode  
controller from a V2 device.  
S1  
L1  
V
IN  
V
O
R1  
C1  
Duty Cycle  
D1  
Buck  
Controller  
Slope  
Comp  
Figure 3 illustrates the basic architecture of a V2  
controller.  
Oscillator  
+
FFB  
Error Amplifier  
Latch  
R
S
+
Latch/Drive  
PWM  
R2  
Switch  
+
Z2  
SFB  
V
REF  
+
V
C
V
REF  
PWM  
Comparator  
V
FB  
Z1  
V
O
+
Error  
Amplifier  
2
Clock  
V2 Control Ramp  
V
Control  
Figure 3. V2 Control  
Figure 4. Buck Converter with V2 Control  
In common with V mode or I mode, the feedback signal  
is compared with a reference voltage to develop an error  
signal which is fed to one input of the PWM. The second  
input to the PWM, however, is neither a fixed voltage ramp  
nor the switch current, but rather the feedback signal from  
the output of the converter. This feedback signal provides  
both DC information as well as AC information (the control  
ramp) for the converter to regulate its set point. The control  
architecture is known as V2 since both PWM inputs are  
derived from the converter’s output voltage. This is a little  
misleading because the control ramp is typically generated  
from current information present in the converter.  
V
SWITCH  
V
C
V
FB  
The feedback signal from the buck converter shown in  
Figure 4 is processed in one of two ways before being routed  
to the inputs of the PWM comparator. The Fast Feedback  
path (FFB) adds slope compensation to the feedback signal  
before passing it to one input of the PWM. The Slow  
Feedback path (SFB) compares the original feedback signal  
against a DC reference. The error signal generated at the  
output of the error amplifier VC is filtered by a low  
frequency pole before being routed to the second input of the  
PWM. Each switch cycle is initiated (S1 on), when the  
output latch is set by the oscillator. Each switch cycle  
terminates (S1 off), when the FFB signal (AC plus output  
DC) exceeds SFB (error DC), and the output latch is reset.  
In the event of a load transient, the FFB signal changes  
faster, in relation to the filtered SFB signal, causing duty  
Figure 5.  
In the event of a load transient, the FFB signal changes  
faster, in relation to the filtered SFB signal, causing duty  
cycle modulation to occur. By this means the converter’s  
transient response time is independent of the error amplifier  
bandwidth. The error amplifier is used here to ensure  
excellent DC accuracy.  
In order for the controller to operate optimally, a stable  
ramp is required at the feedback pin.  
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7
 
CS51411, CS51412, CS51413, CS51414  
Control Ramp Generation  
V
IN  
In original V2 designs, the control ramp VCR was  
generated from the converter’s output ripple. Using a current  
derived ramp provides the same benefits as current mode,  
namely input feed forward, single pole output filter  
compensation and fast feedback following output load  
transients. Typically a tantalum or organic polymer  
capacitor is selected having a sufficiently large ESR  
component, relative to its capacitive and ESL ripple  
contributions, to ensure the control ramp was sensing  
inductor current and its amplitude was sufficient to maintain  
loop stability. This technique is illustrated in Figure 6.  
V
OUT  
C
R
V
FB  
Figure 7. Control Ramp Generated from DCR  
Inductor Sensing  
V
IN  
V
OUT  
L
C
C
esr  
V
FB  
Figure 6. Control Ramp Generated from Output  
Advances in multilayer ceramic capacitor technology are  
such that MLCC’s can provide a cost effective filter solution  
for low voltage (< 12 V), high frequency converters  
(>200 kHz). For example, a 10 mF MLCC 16 V in a  
805 SMT package has an ESR of 2 mW and an ESL of  
100 nH. Using several MLCC’s in parallel, connected to  
power and ground planes on a PCB with multiple vias, can  
provide a “near perfect” capacitor. Using this technique,  
output switching ripple below 10 mV can be readily  
obtained since parasitic ESR and ESL ripple contributions  
are nil. In this case, the control ramp is generated elsewhere  
in the circuit.  
Ramp generation using dcr inductor current sensing,  
where the L/DCR time constant of the output inductor is  
matched with the CR time constant of the integrating  
network, is shown in Figure 7. The converter’s transient  
response following a 1 A step load is shown in Figure 8. This  
transient response is indicative of a closed loop in excess of  
10 kHz having good gain and phase margin in the frequency  
domain. Also note the amplitude of output switching ripple  
provided by just two 10 mF MLCC’s.  
Figure 8.  
Ramp generation using a voltage feed forward technique  
is illustrated in Figure 9.  
V
IN  
V
OUT  
C
R
C
Z
f
f
V
FB  
Figure 9. Control Ramp from Voltage Feed Forward  
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CS51411, CS51412, CS51413, CS51414  
Some representative efficiency data is shown in Figure 10.  
100  
80  
60  
40  
20  
0
Vin = 5.5 V, Vout= 3.3 V  
Vin = 7.5 V, Vout = 5.0 V  
Vin = 15V, Vout = 12 V  
Figure 11. A CS51411 Buck Regulator is Synced by an  
External 350 kHz Pulse Signal  
0
500  
1000  
1500  
I
, OUTPUT CURRENT (mA)  
OUT  
Figure 10. Efficiency versus Output Current  
Power Switch and Current Limit  
The collector of the built−in NPN power switch is  
connected to the V pin, and the emitter to the V pin.  
More detailed information is available in the ON  
Semiconductor application note AND8276/D on V2 and the  
CS5141x demonstration board number.  
IN  
SW  
When the switch turns on, the V voltage is equal to the  
SW  
V
the V  
minus switch Saturation Voltage. In the buck regulator,  
IN  
Error Amplifier  
voltage swings to one diode drop below ground  
SW  
The CS5141X has a transconductance error amplifier,  
whose noninverting input is connected to an Internal  
Reference Voltage generated from the on−chip regulator. The  
inverting input connects to the V pin. The output of the  
error amplifier is made available at the V pin. A typical  
frequency compensation requires only a 0.1 mF capacitor  
connected between the V pin and ground, as shown in  
Figure 1. This capacitor and error amplifier’s output  
resistance (approximately 8.0 MW) create a low frequency  
pole to limit the bandwidth. Since V2 control does not require  
when the power switch turns off, and the inductor current is  
commutated to the catch diode. Due to the presence of high  
pulsed current, the traces connecting the V pin, inductor  
and diode should be kept as short as possible to minimize the  
noise and radiation. For the same reason, the input capacitor  
should be placed close to the V pin and the anode of the  
SW  
FB  
C
IN  
C
diode.  
The saturation voltage of the power switch is dependent  
on the switching current, as shown in Figure 12.  
a
high bandwidth error amplifier, the frequency  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
compensation is greatly simplified.  
The V pin is clamped below Output High Voltage. This  
C
allows the regulator to recover quickly from overcurrent or  
short circuit conditions.  
Oscillator and Sync Feature (CS51411 and CS51413 only)  
The on−chip oscillator is trimmed at the factory and requires  
no external components for frequency control. The high  
switching frequency allows smaller external components to be  
used, resulting in a board area and cost savings. The tight  
frequency tolerance simplifies magnetic components election.  
The switching frequency is reduced to 25% of the nominal  
0.1  
0
value when the V pin voltage is below Frequency Foldback  
FB  
0
0.5  
1.0  
1.5  
Threshold. In short circuit or overload conditions, this reduces  
the power dissipation of the IC and external components.  
An external clock signal can sync CS51411/CS51414 to a  
higher frequency. The rising edge of the sync pulse turns on the  
power switch to start a new switching cycle, as shown in  
Figure 11. There is approximately 0.5 ms delay between the  
SWITCHING CURRENT (A)  
Figure 12. The Saturation Voltage of the Power Switch  
Increases with the Conducting Current  
Members of the CS5141X family contain pulse−by−pulse  
current limiting to protect the power switch and external  
components. When the peak of the switching current reaches  
the Current Limit, the power switch turns off after the  
Current Limit Delay. The switch will not turn on until the  
next switching cycle. The current limit threshold is  
rising edge of the sync pulse and rising edge of the V pin  
SW  
voltage. The sync threshold is TTL logic compatible, and duty  
cycle of the sync pulses can vary from 10% to 90%. The  
frequency foldback feature is disabled during the sync mode.  
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CS51411, CS51412, CS51413, CS51414  
independent of switching duty cycle. The maximum load  
As shown in Figure 14, the BOOST pin current includes a  
constant 7.0 mA predriver current and base current  
proportional to switch conducting current. A detailed  
discussion of this current is conducted in Thermal  
Consideration section. A 0.1 mF capacitor is usually adequate  
for maintaining the Boost pin voltage during the on time.  
current, given by the following formula under continuous  
conduction mode, is less than the Current Limit due to the  
ripple current.  
V (V * V )  
IN  
O
O
I
+ I *  
LIM  
O(MAX)  
2(L)(V )(f )  
IN  
s
where:  
f = switching frequency,  
BIAS Pin (CS51412 and CS51414 Only)  
S
The BIAS pin allows a secondary power supply to bias the  
control circuitry of the IC. The BIAS pin voltage should be  
between 3.3 V and 6.0 V. If the BIAS pin voltage falls below  
that range, use a diode to prevent current drain from the  
BIAS pin. Powering the IC with a voltage lower than the  
regulator’s input voltage reduces the IC power dissipation  
and improves energy transfer efficiency.  
I
= current limit threshold,  
LIM  
V = output voltage,  
O
V
IN  
= input voltage,  
L = inductor value.  
When the regulator runs undercurrent limit, the  
subharmonic oscillation may cause low frequency  
oscillation, as shown in Figure 13. Similar to current mode  
control, this oscillation occurs at the duty cycle greater than  
50% and can be alleviated by using a larger inductor value.  
The current limit threshold is reduced to Foldback Current  
when the FB pin falls below Foldback Threshold. This  
feature protects the IC and external components under the  
power up or overload conditions.  
30  
25  
20  
15  
10  
5
0
0
0.5  
1.0  
1.5  
SWITCHING CURRENT (A)  
Figure 14. The Boost Pin Current Includes 7.0 mA  
Predriver Current and Base Current when the Switch  
is Turned On. The Beta Decline of the Power Switch  
Further Increases the Base Current at High  
Switching Current  
Shutdown  
The internal power switch will not turn on until the V pin  
IN  
Figure 13. The Regulator in Current Limit  
rises above the Startup Voltage. This ensures no switching  
until adequate supply voltage is provided to the IC.  
The IC enters a sleep mode when the SHDNB pin is pulled  
below Shutdown Threshold Voltage. In the sleep mode, the  
power switch keeps open and the supply current reduces to  
Shutdown Quiescent Current. This pin has internal pull−up  
current. So when this pin is not used, leave the SHDNB pin  
open.  
BOOST Pin  
The BOOST pin provides base driving current for the  
power switch. A voltage higher than V provides required  
IN  
headroom to turn on the power switch. This in turn reduces  
IC power dissipation and improves overall system  
efficiency. The BOOST pin can be connected to an external  
boost−strapping circuit which typically uses a 0.1 mF capacitor  
and a 1N914 or 1N4148 diode, as shown in Figure 1. When the  
power switch is turned on, the voltage on the BOOST pin is  
equal to  
Startup  
During power up, the regulator tends to quickly charge up  
the output capacitors to reach voltage regulation. This gives  
rise to an excessive in−rush current which can be detrimental  
V
+ V ) V * V  
IN F  
BOOST  
O
2
to the inductor, IC and catch diode. In V control, the  
where:  
V = diode forward voltage.  
The anode of the diode can be connected to any DC voltage  
other than the regulated output voltage. However, the  
maximum voltage on the BOOST pin shall not exceed 40 V.  
compensation capacitor provides Soft−Start with no need  
for extra pin or circuitry. During the power up, the Output  
Source Current of the error amplifier charges the  
F
compensation capacitor which forces V pin and thus output  
C
voltage ramp up gradually.  
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CS51411, CS51412, CS51413, CS51414  
The Soft−Start duration can be calculated by  
diode current. The short circuit waveforms are captured in  
Figure 16, and the benefit of the foldback frequency and  
current limit is self−evident.  
V
  C  
C
I
COMP  
T
+
SS  
SOURCE  
where:  
V = V pin steady−state voltage, which is approximately  
C
C
equal to error amplifier’s reference voltage.  
C
COMP  
= Compensation capacitor connected to the V pin  
C
I
= Output Source Current of the error amplifier.  
SOURCE  
Using a 0.1 mF C , the calculation shows a T over  
COMP SS  
5.0 ms which is adequate to avoid any current stresses.  
Figure 15 shows the gradual rise of the V , V and envelope  
C
O
of the V during power up. There is no voltage overshoot  
SW  
after the output voltage reaches the regulation. If the supply  
voltage rises slower than the V pin, output voltage may  
C
overshoot.  
Figure 16. In Short Circuit, the Foldback Current and  
Foldback Frequency Limit the Switching Current to  
Protect the IC, Inductor and Catch Diode  
Thermal Considerations  
A calculation of the power dissipation of the IC is always  
necessary prior to the adoption of the regulator. The current  
drawn by the IC includes quiescent current, predriver  
current, and power switch base current. The quiescent  
current drives the low power circuits in the IC, which  
include comparators, error amplifier and other logic blocks.  
Therefore, this current is independent of the switching  
current and generates power equal to  
Figure 15. The Power Up Transition of CS5141X  
Regulator  
W
+ V   I  
IN  
Q
Q
where:  
I = quiescent current.  
Short Circuit  
Q
When the V  
pin voltage drops below Foldback  
FB  
The predriver current is used to turn on/off the power  
switch and is approximately equal to 12 mA in worst case.  
During steady state operation, the IC draws this current from  
the Boost pin when the power switch is on and then receives  
Threshold, the regulator reduces the peak current limit by  
40% and switching frequency to 1/4 of the nominal  
frequency. These features are designed to protect the IC and  
external components during overload or short circuit  
conditions. In those conditions, peak switching current is  
clamped to the current limit threshold. The reduced  
switching frequency significantly increases the ripple  
current, and thus lowers the DC current. The short circuit can  
cause the minimum duty cycle to be limited by Minimum  
Output Pulse Width. The foldback frequency reduces the  
minimum duty cycle by extending the switching cycle. This  
protects the IC from overheating, and also limits the power  
that can be transferred to the output. The current limit  
foldback effectively reduces the current stress on the  
inductor and diode. When the output is shorted, the DC  
current of the inductor and diode can approach the current  
limit threshold. Therefore, reducing the current limit by 40%  
can result in an equal percentage drop of the inductor and  
it from the V pin when the switch is off. The predriver  
IN  
current always returns to the V pin. Since the predriver  
SW  
current goes out to the regulator’s output even when the  
power switch is turned off, a minimum load is required to  
prevent overvoltage in light load conditions. If the Boost pin  
voltage is equal to V + V when the switch is on, the power  
IN  
O
dissipation due to predriver current can be calculated by  
2
V
V
O
W
+ 12 mA   (V * V  
IN  
)
O
)
DRV  
IN  
The base current of a bipolar transistor is equal to collector  
current divided by beta of the device. Beta of 60 is used here  
to estimate the base current. The Boost pin provides the base  
current when the transistor needs to be on.  
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11  
 
CS51411, CS51412, CS51413, CS51414  
The power dissipated by the IC due to this current is  
Internal bias to the IC can be supplied via the V pin or the  
in  
BIAS pin. When the BIAS pin is low, the logic turns P2 on  
and current is routed to the internal bias circuitry from the  
2
V
V
I
S
60  
O
W
+
 
BASE  
IN  
V
in  
pin. Conversely, when the BIAS pin is high, the logic  
where:  
I = DC switching current.  
turns P1 on and current is routed to the internal bias circuitry  
from the BIAS pin.  
S
When the power switch turns on, the saturation voltage  
and conduction current contribute to the power loss of a  
non−ideal switch. The power loss can be quantified as  
Here is an example of the power savings:  
The input voltage range for V is 4.5 V to 40 V. The input  
in  
voltage range for BIAS is 3.3 V to 6 V. The quiescent current  
specification is 3 mA (min), 4 mA (typ), and 6.25 mA (max).  
Using a typical battery voltage of 14 V and the typical  
quiescent current number of 4 mA, the power would be:  
V
O
W
+
  I   V  
S SAT  
SAT  
V
IN  
where:  
P + V   I + 14   4e−3 + 56 mW  
V
SAT  
= saturation voltage of the power switch which is  
shown in Figure 12.  
We’ll assume the BIAS pin is connected to an external  
regulator at 5 V instead of the output voltage. The BIAS pin  
would normally be connected to the output voltage, but  
adding an added switching regulator efficiency number here  
would cloud this example. Now the internal BIAS circuitry  
is being powered via 5 V. The resulting on chip power being  
dissipated is:  
The switching loss occurs when the switch experiences  
both high current and voltage during each switch transition.  
This regulator has a 30 ns turn−off time and associated  
power loss is equal to  
I
S
  V  
2
IN  
W
+
  30 ns   f  
S
S
P + V   I + 5   4e−3 + 21 mW  
The turn−on time is much shorter and thus turn−on loss is  
not considered here.  
The power savings is 35 mW.  
Now, to demonstrate more notable savings using the  
maximum battery input voltage of 40 V, the maximum  
quiescent current of 6.25 mA, and the lowest allowed BIAS  
voltage for proper operation of 3.3 V;  
The total power dissipated by the IC is sum of all the above  
W
+ W ) W  
) W  
) W  
) W  
SAT S  
IC  
Q
DRV  
BASE  
The IC junction temperature can be calculated from the  
ambient temperature, IC power dissipation and thermal  
resistance of the package. The equation is shown as follows,  
Powered from V :  
in  
P + 40   6.25e−3 + 250 mW  
T + W   R  
J IC  
) T  
A
qJA  
Powered from the BIAS pin:  
The maximum IC junction temperature shall not exceed  
125°C to guarantee proper operation and avoid any damages  
to the IC.  
P + 3.3   6.25e−3 + 21 mW  
The power savings is 229 mW.  
Minimum Load Requirement  
Using the BIAS Pin  
As pointed out in the previous section, a minimum load is  
required for this regulator due to the predriver current  
The efficiency savings in using the BIAS pin is most  
notable at low load and high input voltage as will be  
explained below.  
Figure17 will help to understand the increase in efficiency  
when the BIAS pin is used. The circuitry shown is not the  
actual implementation, but is useful in the explanation.  
feeding the output. Placing a resistor equal to V divided by  
O
12 mA should prevent any voltage overshoot at light load  
conditions. Alternatively, the feedback resistors can be  
valued properly to consume 12 mA current.  
COMPONENT SELECTION  
Internal  
P1  
P2  
BIAS  
BIAS  
Input Capacitor  
In a buck converter, the input capacitor witnesses pulsed  
current with an amplitude equal to the load current. This  
pulsed current and the ESR of the input capacitors determine  
the V ripple voltage, which is shown in Figure 18. For V  
IN  
IN  
V
in  
ripple, low ESR is a critical requirement for the input  
capacitor selection. The pulsed input current possesses a  
significant AC component, which is absorbed by the input  
capacitors.  
Figure 17.  
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12  
 
CS51411, CS51412, CS51413, CS51414  
The RMS current of the input capacitor can be calculated  
using:  
Selecting the capacitor type is determined by each  
design’s constraint and emphasis. The aluminum  
electrolytic capacitors are widely available at lowest cost.  
Their ESR and Equivalent Series Inductor (ESL) are  
relatively high. Multiple capacitors are usually paralleled to  
achieve lower ESR. In addition, electrolytic capacitors  
usually need to be paralleled with a ceramic capacitor for  
filtering high frequency noises. The OS−CON are solid  
aluminum electrolytic capacitors, and therefore has a much  
lower ESR. Recently, the price of the OS−CON capacitors  
has dropped significantly so that it is now feasible to use  
them for some low cost designs. Electrolytic capacitors are  
physically large, and not used in applications where the size,  
and especially height is the major concern.  
Ǹ
D(1 * D)  
O
I
+ I  
RMS  
where:  
D = switching duty cycle which is equal to V /V .  
O
IN  
I = load current.  
O
Ceramic capacitors are now available in values over 10 mF.  
Since the ceramic capacitor has low ESR and ESL, a single  
ceramic capacitor can be adequate for both low frequency  
and high frequency noises. The disadvantage of ceramic  
capacitors are their high cost. Solid tantalum capacitors can  
have low ESR and small size. However, the reliability of the  
tantalum capacitor is always a concern in the application  
where the capacitor may experience surge current.  
Output Capacitor  
In a buck converter, the requirements on the output  
capacitor are not as critical as those on the input capacitor.  
The current to the output capacitor comes from the inductor  
and thus is triangular. In most applications, this makes the  
RMS ripple current not an issue in selecting output  
capacitors.  
The output ripple voltage is the sum of a triangular wave  
caused by ripple current flowing through ESR, and a square  
wave due to ESL. Capacitive reactance is assumed to be  
small compared to ESR and ESL. The peak−to−peak ripple  
current of the inductor is:  
Figure 18. Input Voltage Ripple in a Buck Converter  
To calculate the RMS current, multiply the load current  
with the constant given by Figure 19 at each duty cycle. It is  
a common practice to select the input capacitor with an RMS  
current rating more than half the maximum load current. If  
multiple capacitors are paralleled, the RMS current for each  
capacitor should be the total current divided by the number  
of capacitors.  
0.6  
0.5  
V (V * V )  
IN  
O
O
I
+
P * P  
(V )(L)(f )  
IN  
S
0.4  
V , the output ripple due to the ESR, is equal  
RIPPLE(ESR)  
to the product of I  
and ESR. The voltage developed  
P−P  
0.3  
0.2  
across the ESL is proportional to the di/dt of the output  
capacitor. It is realized that the di/dt of the output capacitor  
is the same as the di/dt of the inductor current. Therefore,  
when the switch turns on, the di/dt is equal to (V − V )/L,  
IN  
O
0.1  
0
and it becomes V /L when the switch turns off. The total  
O
ripple voltage induced by ESL can then be derived from  
0
0.2  
0.4  
0.6  
0.8  
1.0  
V
IN  
* V  
L
V
L
V
IN  
L
O
IN  
DUTY CYCLE  
V
+ ESL(  
) ) ESL(  
) + ESL(  
)
RIPPLE(ESL)  
Figure 19. Input Capacitor RMS Current can be  
Calculated by Multiplying Y Value with Maximum Load  
Current at any Duty Cycle  
The total output ripple is the sum of the V  
and  
RIPPLE(ESR)  
V
.
RIPPLE(ESR)  
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Figure 20. The Output Voltage Ripple Using Two 10 mF  
Figure 22. The Output Voltage Ripple Using  
Ceramic Capacitors in Parallel  
One 100 mF OS−CON  
Figure 21. The Output Voltage Ripple Using One 100 mF  
Figure 23. The Output Voltage Ripple Using  
POSCAP Capacitor  
One 100 mF Tantalum Capacitor  
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CS51411, CS51412, CS51413, CS51414  
Figure 20 to Figure 23 show the output ripple of a 5.0 V  
The worse case of the diode average current occurs during  
maximum load current and maximum input voltage. For the  
diode to survive the short circuit condition, the current rating  
of the diode should be equal to the Foldback Current Limit.  
See Table 1 for Schottky diodes from ON Semiconductor  
which are suggested for CS5141X regulator.  
to 3.3 V/500 mA regulator using 22 mH inductor and various  
capacitor types. At the switching frequency, the low ESR  
and ESL make the ceramic capacitors behave capacitively  
as shown in Figure 20. Additional paralleled ceramic  
capacitors will further reduce the ripple voltage, but  
inevitably increase the cost. “POSCAP”, manufactured by  
SANYO, is a solid electrolytic capacitor. The anode is  
sintered tantalum and the cathode is a highly conductive  
polymerized organic semiconductor. TPC series, featuring  
low ESR and low profile, is used in the measurement of  
Figure 21. It is shown that POSCAP presents a good balance  
of capacitance and ESR, compared with a ceramic capacitor.  
In this application, the low ESR generates less than 5.0 mV  
of ripple and the ESL is almost unnoticeable. The ESL of the  
through−hole OS−CON capacitor give rise to the inductive  
impedance. It is evident from Figure 22 which shows the  
step rise of the output ripple on the switch turn−on and large  
spike on the switch turn−off. The ESL prevents the output  
capacitor from quickly charging up the parasitic capacitor of  
the inductor when the switch node is pulled below ground  
through the catch diode conduction. This results in the spike  
associated with the falling edge of the switch node. The D  
package tantalum capacitor used in Figure 23 has the same  
footprint as the POSCAP, but doubles the height. The ESR  
of the tantalum capacitor is apparently higher than the  
POSCAP. The electrolytic and tantalum capacitors provide  
a low−cost solution with compromised performance. The  
reliability of the tantalum capacitor is not a serious concern  
for output filtering because the output capacitor is usually  
free of surge current and voltage.  
Inductor Selection  
When choosing inductors, one might have to consider  
maximum load current, core and copper losses, component  
height, output ripple, EMI, saturation and cost. Lower  
inductor values are chosen to reduce the physical size of the  
inductor. Higher value cuts down the ripple current, core  
losses and allows more output current. For most  
applications, the inductor value falls in the range between  
2.2 mH and 22 mH. The saturation current ratings of the  
inductor shall not exceed the I  
, calculated according to  
L(PK)  
V (V * V )  
O
IN  
O
)
I
+ I  
)
L(PK)  
O
2(f )(L)(V  
S
IN  
The DC current through the inductor is equal to the load  
current. The worse case occurs during maximum load  
current. Check the vendor’s spec to adjust the inductor value  
undercurrent loading. Inductors can lose over 50% of  
inductance when it nears saturation.  
The core materials have a significant effect on inductor  
performance. The ferrite core has benefits of small physical  
size, and very low power dissipation. But be careful not to  
operate these inductors too far beyond their maximum  
ratings for peak current, as this will saturate the core.  
Powered Iron cores are low cost and have a more gradual  
saturation curve. The cores with an open magnetic path, such  
as rod or barrel, tend to generate high magnetic field  
radiation. However, they are usually cheap and small. The  
cores providing a close magnetic loop, such as pot−core and  
toroid, generate low electro−magnetic interference (EMI).  
There are many magnetic component vendors providing  
standard product lines suitable for CS5141X. Table 2 lists  
three vendors, their products and contact information.  
Diode Selection  
The diode in the buck converter provides the inductor  
current path when the power switch turns off. The peak  
reverse voltage is equal to the maximum input voltage. The  
peak conducting current is clamped by the current limit of  
the IC. The average current can be calculated from:  
I (V * V )  
IN  
O
O
I
+
D(AVG)  
V
IN  
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15  
CS51411, CS51412, CS51413, CS51414  
Table 1.  
Part Number  
V
(V)  
I
(A)  
V
(F)  
(V) @ I  
AVERAGE  
Package  
Axial Lead  
Axial Lead  
Axial Lead  
SOD−123  
SOD−123  
SOD−123  
SMB  
BREAKDOWN  
AVERAGE  
1N5817  
1N5818  
20  
1.0  
0.45  
0.55  
0.6  
30  
40  
20  
30  
40  
20  
30  
40  
1.0  
1.0  
0.5  
0.5  
0.5  
1.0  
1.0  
1.0  
1N5819  
MBR0520  
MBR0530  
MBR0540  
MBRS120  
MBRS130  
MBRS140  
0.385  
0.43  
0.53  
0.55  
0.395  
0.6  
SMB  
SMB  
Table 2.  
Vendor  
Product Family  
UNI−Pac1/2: SMT, barrel  
Web Site  
Telephone  
Coiltronics  
www.coiltronics.com  
(516) 241−7876  
THIN−PAC: SMT, toroid, low profile  
CTX: Leaded, toroid  
Coilcraft  
Pulse  
DO1608: SMT, barrel  
DS/DT 1608: SMT, barrel, magnetically shielded  
DO3316: SMT, barrel  
DS/DT 3316: SMT, barrel, magnetically shielded  
DO3308: SMT, barrel, low profile  
www.coilcraft.com  
(800) 322−2645  
(619) 674−8100  
www.pulseeng.com  
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16  
CS51411, CS51412, CS51413, CS51414  
R2  
373  
U1  
7
V
5.0 V − 12 V input  
C1  
C5  
0.1 mF  
D2  
L1  
2
4
FB  
V
IN  
1N4148  
1
3
BOOST  
22 mF  
SHDNB  
CS51411/3  
V
SW  
5
15 mH  
R3  
SYNC  
V
C
GND  
6
127  
D1  
MBR0520  
C6  
22 m  
8
C2  
0.1 mF  
−5.0 V output  
C3  
C4  
0.01 mF  
R1  
50 k  
0.1 mF  
Figure 24. Additional Application Diagram, 5.0 V − 12 V to −5.0 V/400 mA Inverting Converter  
1N4148  
D2  
1N4148  
D1  
12 V  
C1  
0.1 mF  
C1  
100 mF  
U1  
2
1
4
3
V
BIAS  
BOOST  
5.0 V  
IN  
V
SW  
L1  
15 mH  
5
Shutdown  
SHDNB  
CS51412/4  
R1  
373  
C3  
100 mF  
D3  
1N5821  
V
V
7
GND  
C
FB  
8
6
R2  
127  
C4  
0.1 mF  
Figure 25. Additional Application Diagram, 12 V to 5.0 V/1.0 A Buck Converter using the BIAS Pin  
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17  
CS51411, CS51412, CS51413, CS51414  
ORDERING INFORMATION  
Device  
Operating Temperature Range  
Package  
SOIC−8  
Shipping  
CS51411ED8  
98 Units/Rail  
98 Units/Rail  
CS51411ED8G  
CS51411EDR8  
CS51411EDR8G  
CS51411EMNR2G  
CS51412ED8  
SOIC−8 (Pb−Free)  
SOIC−8  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
CS51412ED8G  
CS51412EDR8  
CS51412EDR8G  
CS51412EMNR2G  
CS51413ED8  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
−40°C < T < 85°C  
A
CS51413ED8G  
CS51413EDR8  
CS51413EDR8G  
CS51413EMNR2G  
CS51414ED8  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
CS51414ED8G  
CS51414EDR8  
CS51414EDR8G  
CS51414EMNR2G  
CS51411GD8  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
CS51411GD8G  
CS51411GDR8  
CS51411GDR8G  
CS51411GMNR2G  
CS51412GD8  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
CS51412GD8G  
CS51412GDR8  
CS51412GDR8G  
CS51412GMNR2G  
CS51413GD8  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
0°C < T < 70°C  
A
CS51413GD8G  
CS51413GDR8  
CS51413GDR8G  
CS51413GMNR2G  
CS51414GD8  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
98 Units/Rail  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
SOIC−8  
CS51414GD8G  
CS51414GDR8  
CS51414GDR8G  
CS51414GMNR2G  
SOIC−8 (Pb−Free)  
SOIC−8  
98 Units/Rail  
2500 Tape & Reel  
2500 Tape & Reel  
2500 Tape & Reel  
SOIC−8 (Pb−Free)  
DFN18 (Pb−Free)  
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging  
Specifications Brochure, BRD8011/D.  
http://onsemi.com  
18  
CS51411, CS51412, CS51413, CS51414  
PACKAGE DIMENSIONS  
SOIC−8 NB  
CASE 751−07  
ISSUE AH  
NOTES:  
1. DIMENSIONING AND TOLERANCING PER  
ANSI Y14.5M, 1982.  
2. CONTROLLING DIMENSION: MILLIMETER.  
3. DIMENSION A AND B DO NOT INCLUDE  
MOLD PROTRUSION.  
−X−  
A
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)  
PER SIDE.  
8
5
4
5. DIMENSION D DOES NOT INCLUDE DAMBAR  
PROTRUSION. ALLOWABLE DAMBAR  
PROTRUSION SHALL BE 0.127 (0.005) TOTAL  
IN EXCESS OF THE D DIMENSION AT  
MAXIMUM MATERIAL CONDITION.  
6. 751−01 THRU 751−06 ARE OBSOLETE. NEW  
STANDARD IS 751−07.  
S
M
M
B
0.25 (0.010)  
Y
1
K
−Y−  
G
MILLIMETERS  
DIM MIN MAX  
INCHES  
MIN  
MAX  
0.197  
0.157  
0.069  
0.020  
A
B
C
D
G
H
J
K
M
N
S
4.80  
3.80  
1.35  
0.33  
5.00 0.189  
4.00 0.150  
1.75 0.053  
0.51 0.013  
C
N X 45  
_
SEATING  
PLANE  
−Z−  
1.27 BSC  
0.050 BSC  
0.10 (0.004)  
0.10  
0.19  
0.40  
0
0.25 0.004  
0.25 0.007  
1.27 0.016  
0.010  
0.010  
0.050  
8
0.020  
0.244  
M
J
H
D
8
0
_
_
_
_
0.25  
5.80  
0.50 0.010  
6.20 0.228  
M
S
S
X
0.25 (0.010)  
Z
Y
SOLDERING FOOTPRINT*  
1.52  
0.060  
7.0  
4.0  
0.275  
0.155  
0.6  
0.024  
1.270  
0.050  
mm  
inches  
ǒ
Ǔ
SCALE 6:1  
*For additional information on our Pb−Free strategy and soldering  
details, please download the ON Semiconductor Soldering and  
Mounting Techniques Reference Manual, SOLDERRM/D.  
PACKAGE THERMAL DATA  
Parameter  
SOIC−8  
45  
Unit  
°C/W  
°C/W  
R
Typical  
Typical  
q
q
JC  
JA  
R
165  
http://onsemi.com  
19  
CS51411, CS51412, CS51413, CS51414  
PACKAGE DIMENSIONS  
DFN18  
CASE 505−01  
ISSUE C  
NOTES:  
A
1. DIMENSIONS AND TOLERANCING PER  
D
ASME Y14.5M, 1994.  
B
2. DIMENSIONS IN MILLIMETERS.  
3. DIMENSION b APPLIES TO PLATED  
TERMINAL AND IS MEASURED BETWEEN  
0.25 AND 0.30 MM FROM TERMINAL  
4. COPLANARITY APPLIES TO THE EXPOSED  
PAD AS WELL AS THE TERMINALS.  
PIN 1 LOCATION  
2X  
E
MILLIMETERS  
DIM MIN  
MAX  
1.00  
0.05  
0.15  
C
A
A1  
A3  
b
0.80  
0.00  
0.20 REF  
2X  
0.18  
0.30  
0.15  
C
TOP VIEW  
SIDE VIEW  
D
6.00 BSC  
D2  
E
3.98  
5.00 BSC  
4.28  
(A3)  
0.10  
0.08  
C
C
E2  
e
2.98  
0.50 BSC  
3.28  
A
18X  
K
L
0.20  
0.45  
−−−  
0.65  
A1  
C
SEATING  
PLANE  
SOLDERING FOOTPRINT*  
D2  
e
5.30  
18X  
0.75  
18X L  
1
1
9
0.30  
PITCH  
E2  
18X K  
4.19  
18  
10  
18X b  
18X  
0.30  
0.10 C A  
B
BOTTOM VIEW  
0.05  
C
NOTE 3  
3.24  
DIMENSIONS: MILLIMETERS  
*For additional information on our Pb−Free strategy and soldering  
details, please download the ON Semiconductor Soldering and  
Mounting Techniques Reference Manual, SOLDERRM/D.  
PACKAGE THERMAL DATA  
Parameter  
DFN18  
Unit  
R
Typical  
35  
°C/W  
q
JA  
2
V
is a trademark of Switch Power, Inc.  
ON Semiconductor and  
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice  
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability  
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.  
“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All  
operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights  
nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications  
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should  
Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,  
and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death  
associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal  
Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.  
PUBLICATION ORDERING INFORMATION  
LITERATURE FULFILLMENT:  
N. American Technical Support: 800−282−9855 Toll Free  
USA/Canada  
Europe, Middle East and Africa Technical Support:  
Phone: 421 33 790 2910  
Japan Customer Focus Center  
Phone: 81−3−5773−3850  
ON Semiconductor Website: www.onsemi.com  
Order Literature: http://www.onsemi.com/orderlit  
Literature Distribution Center for ON Semiconductor  
P.O. Box 5163, Denver, Colorado 80217 USA  
Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada  
Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada  
Email: orderlit@onsemi.com  
For additional information, please contact your local  
Sales Representative  
CS51411/D  

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