CXSD6279B电压模式和同步PWM控制器驱动双N通道mosfet控制监视和保护功能受控电源带欠压和过流保护的输出

CXSD6279B提供输出负载变化的良好调节。内部0.8V温度-补偿参考电压的设计满足
低输出电压应用。它包括一个200kHz的自由运行三角波振荡器，可从70kHz调整到800kHz。上电复位（POR）电路监控VCC、EN和OCSET启动或关闭集成电路的输入电压。过电流保护（OCP）使用上部的电压降监测输出电流MOSFET的RDS（开），消除了对电流传感电阻的需要。欠压保护（UVP）监测FB引脚的电压短路保护

目录

1.产品概述                       2.产品特点
3.应用范围                       4.下载产品资料PDF文档 
5.产品封装图                     6.电路原理图                   
7.功能概述                        8.相关产品

一,产品概述(General Description)      

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                The CXSD6279B is a voltage mode and synchronous PWM controller
which drives dual N-Channel MOSFETs. It inte-grates the control, monitoring,
and protection functions into a single package, provides one controlled power
outputs with under-voltage and over-current protection.CXSD6279B provides
excellent regulation for output load variation. An internal 0.8V temperature-
compensated reference voltage is designed to meet the requirement of
low output voltage applications. It includes a 200kHz free-running
triangle-wave oscillator that is adjustable from 70kHz to 800kHz.
        The power-on-reset (POR) circuit monitors the VCC, EN,and OCSET
input voltage to start-up or shutdown the IC.The over-current protection (OCP)
monitors the output current by using the voltage drop across the upper
MOSFET’s RDS(ON), eliminating the need for a current sens-ing resistor.
The under-voltage protection (UVP) moni-tors the voltage of the FB pin for
short-circuit protection.The over-current protection trip cycle the soft-start
func-tion until the fault events be removed. Under-voltage pro-tection will
shutdown the IC directly.
二.产品特点(Features)

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1.)Simple Single-Loop Control Design
   Voltage-Mode PWM Control
2.)Fast Transient Response
    Full 0–100% Duty Ratio
3.)Excellent Output Voltage Regulation
   0.8V Internal Reference
    ± 1% Over Line Voltage and Temperature
4.)Over Current Fault Monitor
   Uses Upper MOSFETs RDS (ON)
5.)Converter Can Source and Sink Current
6.)Small Converter Size
    200kHz Free-Running Oscillator
   Programmable from 70kHz to 800kHz
7.)14-Lead SOIC Package
8.)Lead Free and Green Devices Available (RoHS Compliant)
三,应用范围 (Applications)

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Graphic Cards
DDR Memory Power Supply
DDR Memory Termination Voltage
Low-Voltage Distributed Power Supplies
四.下载产品资料PDF文档 

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需要详细的PDF规格书请扫一扫微信联系我们，还可以获得免费样品以及技术支持！

 

五,产品封装图 (Package)

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RT (Pin1)
This pin can adjust the switching frequency. Connect a resistor from the RT to the GND for increasing the switch-
OCSET (Pin2)
This pin serves two functions: a shutdown control and the setting of over current-limit threshold. Pulling this pin
below 1.27V will shutdown the controller, forcing the UGATE and LGATE signals to be at 0V.
A resistor (Rocset) connected between this pin and the drain of the high side MOSFET will determine the over 

current limit. An internal 200μA current source will flow through this resistor, creating a voltage drop, which 

will be com-pared with the voltage across the high side MOSFET.
SS (Pin3)
Connect a capacitor from the pin to the GND to set the soft-start interval of the converter. An internal 10μA 

current source charges this capacitor to 5.8V. The SS voltage clamps the error amplifier output, and Figure1

 shows the soft-start interval. At t1, the SS voltage reaches the valley of the oscillator’s triangle wave. The

PWM comparator starts to generate a PWM signal to control logic, and the
COMP (Pin4)
This pin is the output of the error amplifier. Add an exter-nal resistor and capacitor network to provide the

 loop com- pensation for the PW M converter (see Application Information).
FB (Pin5)
FB pin is the inverter input of the error amplifier and it receives the feedback voltage from an external 

resis-tive divider across the output (V OUT). The output voltage is determined by:
EN (Pin6)
Pull the pin higher than 2V to enable the device, and pull the pin lower than 0.8V to shutdown the 

device. In shutdown, the SS is discharged and the UGATE and LGATE pins are held low. The EN pin 

is the open-collector, and it will not be floating. 
GND (Pin7)
Signal ground for the IC. 
PHASE (Pin8)
This pin is connected to the source of the high-side MOSFET and is used to monitor the voltage drop

 across the high-side MOSFET for over-current protection. 
UGATE (Pin9)
Connect the pin to external MOSFET, and provides the gate drive for the upper MOSFET.

BOOT (Pin 10)
This pin provides the supply voltage to the high side MOSFET driver. For driving logic level N-channel 

MOSEFT,a bootstrap circuit can be used to create a suitable driver’s supply. 
PGND (Pin11)
Power ground for the gate diver. Connect the lower MOSFET source to this pin. 
LGATE (Pin 12)

Connect the pin to the external MOSFET, and provides the gate drive signal for the lower MOSFET.
PVCC (Pin13)
This pin provides a supply voltage for the lower gate drive, connect it to the VCC pin in common use. 
VCC (Pin14)
This pin provides a supply voltage for the device. When the VCC is above the rising threshold 10.4V, 

the device is turned on; conversely, when the VCC is below the falling threshold, the device is turned off.
六.电路原理图

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七,功能概述

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Output Capacitor Selection
The selection of COUT is determined by the required effec-tive series resistance (ESR) and voltage rating

 rather than the actual capacitance requirement. Therefore, select highperformance low ESR capacitors 

that are intended for switching regulator applications. In some applications,multiple capacitors have to

 be paralled to achieve the desired ESR value. If tantalum capacitors are used, makesure they are surge

 tested by the manufactures. If in doubt,consult the capacitors manufacturer.
 Input Capacitor Selection
The input capacitor is chosen based on the voltage rating and the RMS current rating. For reliable 

operation, select the capacitor voltage rating to be at least 1.3 times higher than the maximum input

 voltage. The maximum RMS current rating requirement is approximately IOUT/2 , where IOUT is the 

load current. During power up, the input capaci-tors have to handle large amount of surge current.

 If tanta-lum capacitors are used, make sure they are surge tested by the manufactures. If in doubt, 

consult the capacitors manufacturer.For high frequency decoupling, a ceramic capacitor be-tween

 0.1μF to 1μF can be connected between the VCC and the ground pin.
Inductor Selection
The inductance of the inductor is determined by the out-put voltage requirement. The larger the 

inductance, the lower the inductor’s current ripple. This will translate into lower output ripple voltage.

 The ripple current and ripple voltage can be approximated by:
where Fs is the switching frequency of the regulator.There is a tradeoff exists between the inductor’s

 ripple current and the regulator load transient response time. A smaller inductor will give the regulator 

a faster load tran-sient response at the expense of higher ripple current and vice versa. The maximum

 ripple current occurs at the maximum input voltage. A good starting point is to choose the ripple 

current to be approximately 30% of the maxi-mum output current.Once the inductance value has 

been chosen, select an inductor that is capable of carrying the required peak cur-rent without going 

into saturation. In some types of inductors, especially core that is make of ferrite, the ripple
current will increase abruptly when it saturates. This will result in a larger output ripple voltage.
Compensation
The output LC filter introduces a double pole, which con-tributes with –40dB/decade gain slope and 

180 degrees phase shift in the control loop. A compensation network between the COMP pin and the 

ground should be added. The simplest loop compensation network is shown in
Figure 5.
The output LC filter consists of the output inductor and output capacitors. The transfer function of

 the LC filter is given by:
八,相关产品                     更多同类产品...... 

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Switching Regulator >   Buck Controller
Part_No	Package	Archi tectu	Phase	No.of PWM Output	Output  Current (A)	Input Voltage (V)		Reference Voltage (V)	Bias  Voltage (V)	Quiescent Current (uA)
						min	max
CXSD6273	SOP-14 QSOP-16 QFN4x4-16	VM	1	1	30	2.9	13.2	0.9	12	8000
CXSD6274	SOP-8	VM	1	1	20	2.9	13.2	0.8	12	5000
CXSD6274C	SOP-8	VM	1	1	20	2.9	13.2	0.8	12	5000
CXSD6275	QFN4x4-24	VM	2	1	60	3.1	13.2	0.6	12	5000
CXSD6276	SOP-8	VM	1	1	20	2.2	13.2	0.8	5~12	2100
CXSD6276A	SOP-8	VM	1	1	20	2.2	13.2	0.8	5~12	2100
CXSD6277/A/B	SOP8|TSSOP8	VM	1	1	5	5	13.2	1.25|0.8	5~12	3000
CXSD6278	SOP-8	VM	1	1	10	3.3	5.5	0.8	5	2100
CXSD6279B	SOP-14	VM	1	1	10	5	13.2	0.8	12	2000
CXSD6280	TSSOP-24 |QFN5x5-32	VM	1	2	20	5	13.2	0.6	5~12	4000
CXSD6281N	SOP14 QSOP16 QFN-16	VM	1	1	30	2.9	13.2	0.9	12	4000
CXSD6282	SOP-14	VM	1	1	30	2.2	13.2	0.6	12	5000
CXSD6282A	SOP-14	VM	1	1	30	2.2	13.2	0.6	12	5000
CXSD6283	SOP-14	VM	1	1	25	2.2	13.2	0.8	12	5000
CXSD6284/A	LQFP7x7 48 TQFN7x7-48	VM	1	6	0.015	1.4	6.5	-	5	1800
CXSD6285	TSSOP-24P	VM	1	2	20	2.97	5.5	0.8	5~12	5000
CXSD6286	SOP-14	VM	1	1	10	5	13.2	0.8	12	3000
CXSD6287	SOP-8-P|DIP-8	VM	1	1	30	2.9	13.2	1.2	12	3000
CXSD6288	SSOP28 QFN4x4-24	VM	1	2	20	5	24	0.9	5	1200
CXSD6289	SOP-20	VM	1	2	20	2.2	13.2	0.6	5~12	4000
CXSD6290	SOP8|DFN3x3-10	VM	1	2	-	-	-	-	5~12	550
CXSD6291HC	DIP8|SOP-8	VM	1	1	1	1.2	9	24	5	9 ~ 24
CXSD6292	SSOP16 QFN4x4-16 TQFN3x3-16	VM	1	1	25	3	25	0.6	5	1700
CXSD6293	TDFN3x3-10	COT	1	1	25	3	25	0.5	5	350
CXSD6294	QFN4x4-24	CM	2	1	40	4.5	13.2	0.6	5~12	4000
CXSD6295	SOP8P TDFN3x3-10	VM	1	1	20	3	13.2	0.8	5~12	2500
CXSD6296A|B|C|D	SOP8P	VM	1	1	25	3	13.2	0.6|0.8	5~12	1200
CXSD6297	TDFN3x3-10	VM	1	1	25	4	13.2	0.8	5~12	2000
CXSD6298	TDFN3x3-10	COT	1	1	25	4.5	25	0.6	5~12	80
CXSD6299|A	SOP-8P	VM	1	1	25	4.5	13.2	0.8	5~12	16000
CXSD62100	TQFN3x3-10	VM	1	1	25	4.5	13.2	0.6	5~12	2500
CXSD62101|L	TDFN3x3-10	COT	1	1	30	3	25	0.8	5~12	2000
CXSD62102	TQFN3x3-16	COT	1	1	30	1.8	28	0.6	5	600
CXSD62102A	TQFN 3x3 16	COT	1	1	30	1.8	28	0.6	5	600
CXSD62103	QFN4x4-24	VM	2	1	50	4.5	13.2	0.6	5~12	5000
CXSD62104	TQFN4x4-24	COT	1	2	15	6	25	2	N	550
CXSD62105	TQFN4x4-24	COT	1	2	15	6	25	2	N	550
CXSD62106|A	TQFN4x4-4 TQFN3x3-20	COT	1	2	20	3	28	0.75	5	800
CXSD62107	TQFN3x3-16	COT	1	1	20	1.8	28	0.75	5	400
CXSD62108	QFN3.5x3.5-14 TQFN3x3-16	COT	1	1	20	1.8	28	0.75	5	400
CXSD62109	TQFN3x3-16	COT	1	2	20	1.8	28	0.75	5	400
CXSD62110	QFN3x3-20 TQFN3x3-16	COT	1	2	20	3	28	1.8|1.5|0.5	5	740
CXSD62111	TQFN4x4-24 |QFN3x3-20	CM	1	2	15	5	28	0.5	N	3000
CXSD62112	TDFN3x3-10	COT	1	1	20	1.8	28	0.5	5	250
CXSD62113|C	TQFN3x3-20	COT	1	2	15	6	25	2	N	550
CXSD62113E	TQFN 3x3 20	COT	2	2	11	6	25	2	N	550
CXSD62114	TQFN3x3-20	COT	2	2	11	5.5	25	2	N	280
CXSD62115	QFN4x4-24	VM	2	1	60	3.1	13.2	0.85	12	5000
CXSD62116A|B|C	SOP-8P	VM	1	1	20	2.9	13.2	0.8	12	16000
CXSD62117	SOP-20	VM	2	2	30	10	13.2	1	12	5000
CXSD62118	TDFN3x3-10	COT	1	1	25	1.8	28	0.7	5	250
CXSD62119	TQFN3x3-20	COT	2	1	40	1.8	25	REFIN Setting	5	700
CXSD62120	QFN 3x3 20 TQFN 3x3 16	COT	1	2	20	3	28	1.8|1.5 1.35|1.2 0.5	5	800
CXSD62121A	TQFN3x3 20	COT	1	2	15	3	28	0.75	5	220
CXSD62121B	TQFN3x3 20	COT	1	2	15	3	28	0.75	5	220
CXSD62121	TQFN3x3-20	COT	1	2	20	3	28	0.75	5	180