How it Works
TOREX
Loading...
XCM524
User Manual
52 pgs1.6 Mb0

TOREX XCM524 User Manual

Download
■
■
■
XCM524 Series
ETR2428-003
600mA Synchronous Step-Down DC/DC Converter + 500mA LDO with Delay Function Voltage Detector
GENERAL DESCRIPTION
The XCM524 series is a multi combination module IC which comprises of a 600mA driver transistor built-in synchronous step–down DC/DC converter and a high speed, high current LDO regulator with voltage detector function. The device is housed in small USP-12B01 package which is ideally suited for space conscious applications. The DC/DC converter and the LDO blocks are isolated in the package so that noise interference from the DC/DC to the LDO regulator is minimal.
The DC/DC converter block with a built-in 0.42ΩP-channel MOS driver transistor and 0.52ΩN-channel MOS switching
transistor, designed to allow the use of ceramic capacitors. The DC/DC enables a high efficiency, stable power supply with an output current of 600mA to be configured using only a coil and two capacitors connected externally. The LDO regulator block is precise, low noise, high ripple rejection, low dropout positive voltage regulators with built-in voltage detector. The LDO is also compatible with low ESR ceramic output capacitors. Good output stability is maintained during load fluctuations due to its excellent transient response. The current limiter's fold back circuit also operates as a short circuit protection for the output current. The voltage detector block of the contains delay circuit. The delay time can be controlled by an external capacitor. The detector monitors the input voltage of the voltage regulator.
■APPLICATIONS
●BD, DVD drives
●HDD drives
●Cameras, Video recorders
●Mobile phones, Smart phones
●Various general-purpose power supplies
TYPICAL APPLICATION CIRCUIT
(TOP VIEW)
FEATURES
<DC/DC Convertor Block>
Input Voltage Range : 2.7V ~ 6.0V
Output Voltage Options : 0.8V ~ 4.0V (±2％)
High Efficiency : 92% (TYP.) Output Current : 600mA (MAX.) Oscillation Frequency : 1.2MHz, 3.0MHz (+15%) Current Limiter Circuit Built-In : Constant Current & Latching Control Methods : PWM PWM/PFM Auto
*Performance depends on external components and wiring on PCB wiring.
<Regulator Block> Maximum Output Current
Dropout Voltage : 200mV@I Operating Voltage Range
Output Voltage Options : 0.9V ~ 5.1V (0.1V increments, ±2％) Detect Voltage Options : 2.0V ~ 5.5V (0.1V increments, ±2％) VR.VD Temperature Stability :±100ppm/℃ (TYP.)
High Ripple Rejection : 65dB (@10kHz) Low ESR Capacitor : Ceramic Capacitor Operating Temperature Range Package : USP-12B01
Environmentally Friendly : EU RoHS Compliant, Pb Free
: 500mA (Limiter 600mA TYP.)
(2.5V≦V
: 2.0V ~ 6.0V
: -40℃ ~ +85℃
≦4.9V)
ROUT
=100mA (TYP.)
ROUT
1/52
■
■
XCM524 Series
PIN CONFIGURATIOIN
*DC/DC Ground pin (No.5 and 8) should be short before using the IC.
* A dissipation pad on the reverse side of the package should be electrically isolated.
*1: Voltage level of the VDR’s dissipation pad should be V *2: Voltage level of the DC/DC’s dissipation pad should be V
Care must be taken for an electrical potential of each dissipation pad so as to enhance mounting strength and heat release when the pad needs to be connected to the circuit.
PIN ASSIGNMENT
PIN No XCM524 FUNCTIONS
1 VDOUT VDR Block: VD Output Voltage
2 VSS VDR Block: Ground
3 Cd VDR Block: Delay Capacitor connection
4 V
5 PGND DC/DC Block: Power Ground
6 Lx DC/DC Block: Switching Connection
7 DCOUT DC/DC Block: Output Voltage
8 AGND DC/DC Block: Analog Ground
9 EN2 DC/DC Block: ON/OFF Control
10 V
11 NC No Connection
12 V
(TOP VIEW)
(BOTTOM VIEW)
SS
DC/DC Block: Power Input
IN2
VDR Block: Power Input
IN1
VDR Block: LDO Output
ROUT
PIN No XCM524 VDR DC/DC
level.
level.
SS
1 V
2 VSS V
3 Cd Cd -
4 V
5 PGND - PGND
6 Lx - Lx
7 DCOUT - VOUT
8 AGND - AGND
9 EN2 - CE
10 V
11 NC - -
12 V
V
DOUT
- VIN
IN2
V
IN1
V
ROUT
DOUT
SS
IN1
ROUT
-
-
-
-
2/52
X
■
PRODUCT CLASSIFICATION
●Ordering Information
XCM524A①②③④⑤-⑥ XCM524B①②③④⑤-⑥
(*1)
DC/DC Block: PWM fixed control
(*1)
DC/DC Block: PWM/PFM automatic switching control
DESIGNATOR DESCRIPTION SYMBOL DESCRIPTION
① Oscillation Frequency and Options － See the chart below
②③ Output Voltage － See the chart below
CM524
Series
④⑤-⑥
(*1)
The XCM524 series is Halogen and Antimony free as well as being fully RoHS compliant.
(*2)
The device orientation is fixed in its embossed tape pocket.
Packages
Taping Type
(*2)
DR-G USP-12B01
●DESIGNATOR①
DC/DC BLOCK VDR BLOCK
①
A 1.2M Not Available Standard Available VIN B 3.0M Not Available Standard Available VIN C 1.2M Available High Speed Available VIN D 3.0M Available High Speed Available VIN
OSCILLATION
FREQUENCY
CL
DISCHARGE
SOFT START
VD DELAY
FUNCTION
VD SENSE PIN
Active Low Detect Active Low Detect Active Low Detect Active Low Detect
●DESIGNATOR②③
②③
DCOUT
V
VDF
ROUT
V
01 1.0 3.3 3.7 02 1.2 3.3 3.7 03 1.5 3.3 3.7 04 1.8 3.3 4.2 05 3.3 1.8 2.8 06 1.8 2.5 2.8
*This series are semi-custom products. For other combinations of output voltages please consult with your Torex sales contact.
VD OUTPUT
LOGIC
3/52
■
■
A
XCM524 Series
BLOCK DIAGRAMS
Step-Down DC/DC
R3
R4
Error Amp.
Vref with Soft Start, CE
UVLO
Phase Compensation
VSHORT
PWM/PFM Selector
UVLO Cmp
PWM Comparator
Current Feedback
Current Limit
Logic
Synch Buffer
Drive
Ramp Wave
Generator
OSC
CE/MODE Control Logic
Lx
CE
V
OUT
R2
R1
V
IN
V
SS
V
OUT
R2
R1
V
IN
V
SS
* A fixed PWM control scheme because that the “CE Control Logic” outputs a low level signal to the “PWM/PFM Selector”.
* An auto PWM/PFM switching control scheme because the “CE Control Logic” outputs a high level signal to the “PWM/PFM Selector”.
*Diodes inside the circuit are an ESD protection diode and a parasitic diode.
  Ta=25℃
BSOLUTE MAXIMUM RATINGS
PAR AMETER SYMBOL RATINGS UNITS
V
VROUT Current I
VROUT Voltage V
VDOUT Current I
VDOUT Voltage V
VIN2 Current
DCOUT Voltage V
EN2 Voltage V
Power
Dissipation
Voltage V
IN1
Cd Voltage VCd V
Lx Voltage
Lx Current I
USP-12B01 150
USP-12B01
(*2)
(PCB mounted
)
7.0 V
IN1
700
ROUT
V
ROUT
50 mA
DOUT
V
DOUT
V
-0.3 〜 6.5 V
IN2
V
-0.3 〜 V
Lx
-0.3 〜 6.5 V
DCOUT
-0.3 〜 6.5 V
EN2
±1500 mA
Lx
Pd
- 0.3 〜 V
SS
SS
- 0.3 〜 V
SS
800 (Only 1ch operation)
600 (Both 2ch operation)
Junction Temperature Tj 125 ℃
Operating Temperature Range Topr - 40 〜 + 85 ℃
Storage Temperature Range Tstg - 55 〜 + 125 ℃
*1 I
= Less than Pd /（V
ROUT
*2 The power dissipation figure shown is PCB mounted. Please refer to page 50 for details. Please also note that the power dissipation is
for each channel.
IN1-VROUT
）
Step-Down DC/DC
Available with CL Discharge, High Speed Soft-Start
R3
R4
Phase Compensation
Error Amp.
VSHORT
Vref with
PWM/PFM
Soft Start,
Selector
CE
UVLO Cmp
UVLO
(*1)
mA
+ 0.3 V
IN1
PWM Comparator
Current Feedback
Current Limit
Logic
Synch Buffer
Drive
Ramp Wave
Generator
OSC
CE/MODE Control Logic
-0.3 〜 7.0 V
+ 0.3 V
IN1
+ 0.3 ≦ 6.5 V
IN2
CE/
mW
Lx
CE
4/52
X
CM524
Series
■ELECTRICAL CHARACTERISTICS
●XCM524xx 1ch (VDR Block)
Ta =2 5 ℃
PAR A M E T ER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS CIRCUIT
Output Voltage
Maximum Output Current
(0.9 ~ 2.4V)
Maximum Output Current
(2.5 ~ 4.9V)
Load Regulation △V
Dropout Voltage
Supply Current
(FV / FX / FY / FZ series)
Line Regulation
Input Voltage V
Output Voltage
Temperature Characteristics
VOLTAGE REGULATOR
Ripple Rejection Rate PSRR
(*2, 3)
V
(*4)
(V
(△Topr･V
I
ROUT(E)
I
ROUTMAX
I
ROUTMAX
V
V
1mA≦I
ROUT
Higher than V
Vdif1 Vdif2
IDD
△V
IN1･VROUT
△V
/
ROUT
)
2.0 - 6.0 V -
IN1
/
ROUT
)
ROUT
V
V
ROUT(T)
V
ROUT(T)
V
≦0.9V, 2.0V≦V
ROUT(T)
V
ROUT(T)
-40℃≦Topr≦85℃
V
=[V
IN1
ROUT(T)
When V
V
IN1
When V
V
IN1
I
ROUT
=30mA ×0.98 V
ROUT
IN1=VROUT(T)
IN1=VROUT(T)
ROUT(T)
I
ROUT
I
ROUT
IN1=VROUT(T)
≦0.9V, V
+1.0V≦V
I
ROUT
≦1.75V, I
I
ROUT
+2.0V 400 - - mA ①
+2.0V
= 4.0V, V
≦100mA - 15 50 mV ①
ROUT
IN1
=30mA
=100mA
+1.0V
=2.0V
IN1
≦6.0V
IN1
≦6.0V
ROUT
IN1
=10mA
=30mA
=30mA
+1.0]V+0.5Vp-pAC
=2.25V+0.5Vp-pAC
=5.75V+0.5Vp-pAC
ROUT(T)
≧4.75V,
≦1.25V,
ROUT(T)
=50mA, f=10kHz
=6.0V
×1.02 V
ROUT(T)
①
500 - - mA ①
E-1 E-2
mV ① mV ①
- 90 145 μA ②
- 0.01 0.20 % / V ①
- ±100 - ppm /℃ ①
- 65 - dB ③
Current Limiter
(2.4V or less)
Current Limiter
(2.5V or more)
Short-Circuit Current I
Detect Voltage
Hysteresis Range
Supply Current
VOLTAGE DETECTOR
Detect Voltage
(*7, 8)
V
(*8)
V
(*9)
I
Temperature Stability
Delay Resistance R
NOTE:
*1 : Unless otherwise stated, (V
*2 : V
*3 : V
(i.e. the VR output voltage when "V
*4 : Vdif={V
*5 : A voltage equal to 98% of the VR output voltage whenever a stabilized V
*6 : V
*7 : V
*8 : V
*9 : VD output current is sink current at detect.
* The electrical characteristics above are when the other channel is in stop.
：Specified VR output voltage
ROUT(T)
：Effective VR output voltage. Refer to the E-0 chart for values less than V
ROUT(E)
(*6)
1
IN
1：The input voltage when VOUT1, which appears as input voltage is gradually decreased.
IN
：Specified detect voltage value
DF(T)
：Effective detect voltage value.
DF(E)
(*5)
-V
1
}
ROUT
I
V
RLIMl
I
RLIM
RSHORT
DF(E)
HYS
DOUT
△V
(Topr･V
delay
IN1=VROUT(T)
Higher than V
Higher than V
×0.98 V
V
/
DF
)
DF
Delay Resistance =6.0V/Delay Current
+1.0V)
+1.0V" is provided at the VIN pin while maintaining a certain IROUT value).
ROUT(T)
IN1=VROUT(T)
V
IN1=VROUT(T)
V
IN1=VROUT(T)
= 0.5V
DOUT
-40℃≦Topr≦85℃ - ±100 - ppm /℃ ④
V
IN1
+2.0V - 600 - mA ①
+2.0V
= 4.0V, V
ROUT(T)
+2.0V
= 4.0V, V
ROUT(T)
V
= 2.0V 3.0 6.0 -
IN1
V
= 3.0V 4.0 8.0 -
IN1
V
= 4.0V 5.0 10.0 -
IN1
V
= 5.0V 7.0 12.0 -
IN1
V
= 6.0V 10.0 15.0 -
IN1
=6.0V, Cd=0V
IN1
IN1
=6.0V
=6.0V
500 600 - mA ①
- 50 - mA ① ×1.02 V ④
DF(T)
V ×0.02
DF(T)
V
DF(T)
×0.05
V
DF(T)
×0.08
300 500 700 kΩ ⑥
≦1.5V.
DF(T)
ROUT1=IROUT{VROUT(T)+1.0V} is input.
V ④
mA ⑤
5/52
XCM524 Series
■ELECTRICAL CHARACTERISTICS (Continued)
●Dropout Voltage
SYMBOL E-0 E-1 E-1
 PARAMETER
NOMINAL DETECT VOLTAGE OUTPUT VOLTAGE
 
V
ROUT(T)
V
DF(T)
0.90
1.00 0.970 1.030 1000 1100 1050 1200
1.10 1.070 1.130 900 1000 950 1100
1.20 1.170 1.230 800 900 850 1000
1.30 1.270 1.330 700 800 750 900
1.40 1.370 1.430 600 700 650 800
1.50 1.470 1.530 500 600 550 700
1.60 1.568 1.632 400 500 500 600
1.70 1.666 1.734 300 400 400 500
1.80 1.764 1.836 200 300 300 400
1.90 1.862 1.938 120 150 280 380
2.00 1.960 2.040 80 120 240 350
2.10 2.058 2.142 80 120 240 330
2.20 2.156 2.244 80 120 240 330
2.30 2.254 2.346 80 120 240 310
2.40 2.352 2.448 80 120 240 310
2.50 2.450 2.550 70 100 220 290
2.60 2.548 2.652 70 100 220 290
2.70 2.646 2.754 70 100 220 290
2.80 2.744 2.856 70 100 220 270
2.90 2.842 2.958 70 100 220 270
3.00 2.940 3.060 60 90 200 270
3.10 3.038 3.162 60 90 200 250
3.20 3.136 3.264 60 90 200 250
3.30 3.234 3.366 60 90 200 250
3.40 3.332 3.468 60 90 200 250
3.50 3.430 3.570 60 90 200 250
3.60 3.528 3.672 60 90 200 250
3.70 3.626 3.774 60 90 200 250
3.80 3.724 3.876 60 90 200 250
3.90 3.822 3.978 60 90 200 250
4.00 3.920 4.080 60 80 180 230
4.10 4.018 4.182 60 80 180 230
4.20 4.116 4.284 60 80 180 230
4.30 4.214 4.386 60 80 180 230
4.40 4.312 4.488 60 80 180 230
4.50 4.410 4.590 60 80 180 230
4.60 4.508 4.692 60 80 180 230
4.70 4.606 4.794 60 80 180 230
4.80 4.704 4.896 60 80 180 230
4.90 4.802 4.998 60 80 180 230
5.00 4.900 5.100 50 70 160 210
5.10 4.998 5.202 50 70 160 210
5.20 5.096 5.304
5.30 5.194 5.406
5.40 5.292 5.508
5.50 5.390 5.610
OUTPUT VOLTAGE
DETECT VOLTAGE
(V)
V
/ V
ROUT(E)
MIN. MAX. TYP. MAX. TYP. MAX.
0.870 0.930 1050 1100 1150 1200
Vdif1 Vdif1 Vdif2 Vdif2
DF(E)
DROPOUT VOLTAGE 1 (mV)
(I
=30mA)
OUT
Ta =2 5 ℃ Ta =2 5 ℃
DROPOUT VOLTAGE 2 (mV)
(I
=100mA)
OUT
6/52
X
■ELECTRICAL CHARACTERISTICS (Continued)
CM524
Series
●XCM524xA 2ch (DC/DC Block) V
DCOUT
=1.8V, f
=1.2MHz, Ta=25℃
OSC
PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS
Output Voltage V
Operating Voltage Range V
Maximum Output Current I
UVLO Voltage V
DCOUT
2.7 - 6.0 V
IN2
OUT2MAX
UVLO
Supply Current IDD V
Stand-by Current I
Oscillation Frequency f
PFM Switching Current I
PFM Duty Limit DTY
Maximum Duty Cycle D
Minimum Duty Cycle D
Efficiency
(*2)
EFFI
Lx SW "H" ON Resistance 1 R
Lx SW "H" ON Resistance 2 R
Lx SW "L" ON Resistance 1 R
Lx SW "L" ON Resistance 2 R
Lx SW "H" Leak Current
Lx SW "L" Leak Current
Current Limit
(*5)
I
(*5)
I
(*9)
I
Output Voltage
Temperature
Characteristics
EN "H" Voltage V
EN "L" Voltage V
EN "H" Current I
EN "L" Current I
V
STB
OSC
PFM
LIMIT_PFM
MAX
V
MIN
LXH1
LXH2
LXL1
LXL2
LEAKH
LEAKL
V
LIM
△
V
DCOUT
(V
･△T
DCOUT
ENH
ENL
V
ENH
V
ENL
V
V
V
V
V
V
V
/
opr)
Soft Start Time tSS
Latch Time t
Short Protection
Threshold Voltage
V
LAT
SHORT
Test conditions: Unless otherwise stated, V
When connected to external components, V
When connected to external components, V
V Voltage which Lx pin holding “L” level
=5.0V,I
IN2=VEN2
IN2=VDCOUT(T)
=5.0V,V
=5.0V,V
V
，
EN2=VIN2
IN2=VEN2
IN2
OUT2
+2.0V,V
=0V,
DCOUT
DCOUT=VDCOUT(T)
=0V,V
EN2
=30mA
(*8)
=1.0V
EN2
×1.1V
DCOUT=VDCOUT(T)
(*1, *10)
×1.1V - 0 1.0 μA
When connected to external components, V
IN2=VDCOUT(T)
When connected to external components, V
IN2=VDCOUT(T)
V
EN2=VIN2
IN2=VEN2
IN2=VEN2
When connected to external components, V
EN2=VIN2＝VDCOUT(T)
IN2=VEN2
IN2=VEN2
IN2=VEN2
IN2=VEN2
IN2=VDCOUT
IN2=VDCOUT
IN2=VEN2
I
=30mA
OUT2
-40℃≦Topr≦85℃
V
DCOUT
Voltage changes Lx to “H” level V
DCOUT
Voltage changes Lx to “L” level
IN2=VEN2
=5.0V,V
IN2
+2.0V,V
+2.0V,V
=(C-1) I
=5.0V,V
=5.0V,V
=5.0V,V
=3.6V,V
=5.0V
=3.6V
=5.0V,V
=5.0V,V
=5.0V,V
=1.0V, I
EN2
, I
EN2=VIN2
(*11)
=1mA
OUT2
DCOUT=VDCOUT(T)
DCOUT=VDCOUT(T)
(*7)
+1.2V
DCOUT
DCOUT
(*4)
- 0.45 0.66 Ω
(*4)
- 0.52 0.77 Ω
EN2
EN2
DCOUT=VDCOUT(T)
, I
=0V,ILX=100mA
=0V,ILX=100mA
=0V,L
=0V - 0.01 1.0 μA
X
=0V,L
=5.0V - 0.01 1.0 μA
X
=0V, Applied voltage to V
=0V, Applied voltage to V
=5.0V,V
EN2
=0V - 0.1 - 0.1 μA
DCOUT
=0V,V
=0V - 0.1 - 0.1 μA
DCOUT
=100mA
OUT1
(*11)
=1mA
OUT2
200 %
×0.9V 100 - - %
×1.1V - - 0 %
=100mA
OUT2
(*3)
- 0.35 0.55 Ω
(*3)
- 0.42 0.67 Ω
×0.9V 900 1050 1350 mA
EN2,
(*10)
EN2 (*10)
When connected to external components, V
=0V→V
EN2
V
IN2=VEN2
=5.0V, V Short Lx at 1Ω resistance Sweeping
V
IN2,IOUT1
, V
DCOUT
=1mA
DCOUT
IN2=VEN2
=0.8×V
(*6)
=5.0V,
DCOUT(T)
Short Lx at 1Ω resistance, DCOUT voltage which Lx becomes “ Lx=L ” within 1ms
=5.0V V
IN2
DCOUT(T)
= Setting voltage
(XCM524AA) - 22 50
(XCM524BA)
1.764 1.800 1.836 V ⑦
600 - - mA
1.00 1.40 1.78 V
- 15 33
1020 1200 1380 kHz
120 160 200 mA
- 92 - %
- ±100 - ppm/℃
0.65 - 6.0 V
V
- 0.25 V
SS
0.5 1.0 2.5 ms
1.0 - 20.0 ms
0.675 0.900 1.125 V
NOTE: *1: Including hysteresis width of operating voltage.
*2: EFFI = { ( output voltage×output current ) /( input voltage×input current) }×100 *3: ON resistance (Ω)= (V
- Lx pin measurement voltage) /100mA
IN2
*4: Design value
*5: When temperature is high, a current of approximately 10μA (maximum) may leak.
*6:
Time until it short-circuits DCOUT with GND via 1Ωof resistor from an operational state and is set to Lx=0V from current limit pulse generating.
*7: V
DCOUT(T)
+1.2V<2.7V, V
=2.7V.
IN2
*8: When the difference between the input and the output is small, some cycles may be skipped completely before current maximizes.
If current is further pulled from this state, output voltage will decrease because of P-ch driver ON resistance.
*9: Current limit denotes the level of detection at peak of coil current.
*10: "H"＝V
*11: XCM524A series exclude I
- 1.2V, "L"＝+ 0.1V 〜 - 0.1V
IN2〜VIN2
PFM
and DTY
because those are only for the PFM control’s functions.
LIMIT_PFM
* The electrical characteristics above are when the other channel is in stop.
μA
CIRCUIT
⑦ ⑦
⑨
⑧
⑧ ⑦
⑦ ⑦
⑨ ⑨
⑦ ⑩
⑩
−
− ⑪ ⑪ ⑫
⑦
⑨
⑨ ⑪
⑪ ⑦
⑬
⑬
7/52
XCM524 Series
■ELECTRICAL CHARACTERISTICS (Continued)
●XCM524xB 2ch (DC/DC BLOCK) V
DCOUT
=1.8V, f
=3.0MHz, Ta=25℃
OSC
PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS
Output Voltage V
Operating Voltage Range V
Maximum Output Current I
UVLO Voltage V
DCOUT
2.7 - 6.0 V
IN2
OUT2MAX
UVLO
Supply Current IDD V
Stand-by Current I
Oscillation Frequency f
PFM Switching Current I
PFM Duty Limit DTY
Maximum Duty Cycle D
Minimum Duty Cycle D
Efficiency
(*2)
EFFI
Lx SW "H" ON Resistance 1 R
Lx SW "H" ON Resistance 2 R
Lx SW "L" ON Resistance 1 R
Lx SW "L" ON Resistance 2 R
Lx SW "H" Leak Current
Lx SW "L" Leak Current
Current Limit
(*5)
I
(*5)
I
(*9)
I
Output Voltage
Temperature Characteristics
EN "H" Voltage V
EN "L" Voltage V
EN "H" Current I
EN "L" Current I
(V
△
DCOUT
LEAKH
LEAKL
V
STB
OSC
PFM
LIMIT_PFM
MAX
MIN
LXH1
LXH2
LXL1
LXL2
LIM
DCOUT
・△
ENH
ENL
ENH
ENL
V
V
V
V
V
V
V
V
V
V
/
topr)
V
V
Soft Start Time tSS
Latch Time t
Short Protection
Threshold Voltage
V
SHORT
LAT
Test conditions: Unless otherwise stated, V
When connected to external components, V
When connected to external components, V
V
IN2=VEN2
= V
IN2
EN2=VIN2
=5.0V,I
DCOUT(T)
V
DCOUT
，
OUT2
+2.0V,V
=0V,
=30mA
=1.0V
EN1
(*8)
Voltage which Lx pin holding “L” level
IN2=VEN2
=5.0V,V
IN2
=5.0V,V
EN2
DCOUT=VDCOUT(T)
=0V,V
DCOUT=VDCOUT(T)
×1.1V
×1.1V - 0 1.0 μA
When connected to external components, V
IN2=VDCOUT(T)
+2.0V,V
EN2
=1.0V, I
OUT2
=100mA
When connected to external components, V
IN2=VDCOUT(T)
V
EN2=VIN2
IN2=VEN2
IN2=VEN2
When connected to external components, V
EN2=VIN2＝VDCOUT(T)
IN2=VEN2
IN2=VEN2
IN2=VEN1
IN2=VEN1
IN2=VDCOUT
IN2=VDCOUT
IN2=VEN2
I
=30mA
OUT2
-40℃≦Topr≦85℃
V
DCOUT
Voltage changes Lx to “H” level V
DCOUT
Voltage changes Lx to “L” level
IN2=VEN2
=5.0V, V
IN2
+2.0V,V
=(C-1) I
=5.0V,V
=5.0V,V
=5.0V,V
=3.6V,V
=5.0V
=3.6V
=5.0V,V
=5.0V,V
=5.0V,V
OUT2
DCOUT=VDCOUT(T)
DCOUT=VDCOUT(T)
+1.2V
DCOUT
DCOUT
(*4)
- 0.45 0.66 Ω
(*4)
- 0.52 0.77 Ω
EN2
EN2
DCOUT=VDCOUT(T)
, I
EN2=VIN2
(*11)
=1mA
(*7)
, I
=0V,ILX=100mA
=0V,ILX=100mA
=0V,L
=0V - 0.01 1.0 μA
X
=0V,L
=5.0V - 0.01 1.0 μA
X
=0V, Applied voltage to V
=0V, Applied voltage to V
=5.0V, V
EN2
=0V - 0.1 - 0.1 μA
DCOUT
=0V, V
=0V - 0.1 - 0.1 μA
DCOUT
=1mA
OUT2
200 300 %
×0.9V 100 - - %
×1.1V - - 0 %
=100mA
OUT2
×0.9V 900 1050 1350 mA
,
EN2
(*10)
,
EN2
(*10)
When connected to external components, V
=0V→V
EN2
V
IN2=VEN2
=5.0V,V Short Lx at 1Ω resistance Sweeping V
IN2,IOUT2
DCOUT
=1mA
DCOUT
, V
IN2=VEN2
=0.8×V
(*6)
=5.0V,
DCOUT(T)
Short Lx at 1Ω resistance, DCOUT voltage which Lx becomes “ Lx=L ” within 1ms
=5.0V V
IN2
DCOUT(T)
= Setting voltage
(*1, *10)
(XCM524AB) - 46 65
(XCM524BB)
(*11)
(*3)
- 0.35 0.55 Ω
(*3)
- 0.42 0.67 Ω
1.764 1.800 1.836 V ⑦
600 - - mA
1.00 1.40 1.78 V
- 21 35
2550 3000 3450 kHz
170 220 270 mA
- 86 - %
- ±100 - ppm/℃
0.65 - 6.0 V
V
- 0.25 V
SS
0.5 0.9 2.5 ms
1.0 - 20.0 ms
0.675 0.900 1.125 V
NOTE: *1: Including hysteresis width of operating voltage.
*2: EFFI = { ( output voltage×output current ) /( input voltage×input current) }×100 *3: ON resistance (Ω)= (V
- Lx pin measurement voltage) /100mA
IN2
*4: Design value
*5: When temperature is high, a current of approximately 10μA (maximum) may leak.
*6:
Time until it short-circuits DCOUT with GND via 1Ωof resistor from an operational state and is set to Lx=0V from current limit pulse generating.
*7: V
DCOUT(T)
+1.2V<2.7V, V
=2.7V.
IN2
*8: When the difference between the input and the output is small, some cycles may be skipped completely before current maximizes.
If current is further pulled from this state, output voltage will decrease because of P-ch driver ON resistance.
*9: Current limit denotes the level of detection at peak of coil current.
*10: "H"＝V *11: XCM524A series exclude I
- 1.2V, "L"＝+ 0.1V 〜 - 0.1V
IN2〜VIN2
and DTY
PFM
because those are only for the PFM control’s functions.
LIMIT_PFM
* The electrical characteristics above are when the other channel is in stop.
CIRCUIT
⑦ ⑦
⑨
μA ⑧
⑧ ⑦
⑦ ⑦
⑧ ⑧
⑦ ⑩
⑩
−
− ⑪ ⑪ ⑫
⑦
⑨
⑨ ⑪
⑪ ⑦
⑬
⑬
8/52
X
■ELECTRICAL CHARACTERISTICS (Continued)
CM524
Series
●XCM524xC 2ch (DC/DC BLOCK) V
DCOUT
=1.8V, f
=1.2MHz, Ta=25℃
OSC
PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS
Output Voltage V
Operating Voltage Range V
Maximum Output Current I
UVLO Voltage V
DCOUT
2.7 - 6.0 V
IN2
OUT2MAX
UVLO
Supply Current IDD
Stand-by Current I
Oscillation Frequency f
PFM Switching Current I
PFM Duty Limit DTY
Maximum Duty Cycle D
Minimum Duty Cycle D
V
STB
OSC
PFM
LIMIT_PFM
V
MAX
V
MIN
Efficiency EFFI
Lx SW "H" ON Resistance 1 R
Lx SW "H" ON Resistance 2 R
Lx SW "L" ON Resistance 1 R
Lx SW "L" ON Resistance 2 R
Lx SW "H" Leak Current
Current Limit
(*5)
I
(*9)
I
Output Voltage
Temperature Characteristics
EN "H" Voltage V
EN "L" Voltage V
EN "H" Current I
EN "L" Current I
LXH1
LXH2
LXL1
LXL2
LEAKH
LIM
△
V
DCOUT
(V
・△
DCOUT
ENH
ENL
ENH
ENL
V
V
V
V
V
V
/
topr)
V
V
Soft Start Time tSS
Latch Time t
Short Protection
Threshold Voltage
CL Discharge R
V
SHORT
LAT
DCHG
V
Test conditions: Unless otherwise stated, V
When connected to external components, V
When connected to external components, V
V
=5.0V,I
IN2=VEN2
IN2=VDCOUT(T)
EN2=VIN2
V
，
OUT1
+2.0V,V
DCOUT
=30mA
EN2
=0V,
=1.0V
(*8)
Voltage which Lx pin holding “L” level
V
IN2=VEN2
=5.0V,V
IN2
=5.0V,V
EN2
DCOUT=VDCOUT
=0V,V
×1.1V
(T)
DCOUT=VDCOUT(T)
×1.1V - 0 1.0 μA
When connected to external components, V
IN2=VDCOUT(T)
+2.0V,V
EN2
=1.0V, I
OUT2
=100mA
When connected to external components, V
IN2=VDCOUT(T)
V
EN2=VIN2
IN2=VEN2
IN2=VEN2
When connected to external components, V
EN2=VIN2＝VDCOUT(T)
IN2=VEN2
IN2=VEN2
IN2=VEN2
IN2=VEN2
IN1=VDCOUT
IN2=VEN2
I
=30mA
OUT2
-40℃≦Topr≦85℃
V
DCOUT
Voltage changes Lx to “H” level V
DCOUT
Voltage changes Lx to “L” level
IN2=VEN2
=5.0V,V
IN2
+2.0V,V
=(C-1)I
=5.0V, V
=5.0V, V
=5.0V,V
=3.6V,V
=5.0V
=3.6V
=5.0V,V
=5.0V,V
=1mA
OUT2
DCOUT=VDCOUT(T)
DCOUT=VDCOUT(T)
+1.2V
DCOUT
DCOUT
(*4)
- 0.45 0.66 Ω
(*4)
- 0.52 0.77 Ω
EN1
DCOUT=VDCOUT(T)
, I
EN2=VIN2
(*11)
(*7)
, I
=0V,ILX=100mA
=0V,ILX=100mA
=0V,L
=0V - 0.01 1.0 μA
X
=0V, Applied voltage to V
=0V, Applied voltage to V
=5.0V,V
EN2
=0V - 0.1 - 0.1 μA
DCOUT
=0V,V
=0V - 0.1 - 0.1 μA
DCOUT
=1mA
OUT2
- 200 %
×0.9V 100 - - %
×1.1V - - 0 %
=100mA
OUT2
×0.9V 900 1050 1350 mA
EN2,
(*10)
EN2,
(*10)
When connected to external components, V
=0V→V
EN2
V
IN2=VEN2
Short Lx at 1Ω resistance Sweeping V
, I
IN2
=5.0V,V
DCOUT
OUT2
DCOUT
, V
=1mA
=0.8×V
IN2=VEN2
DCOUT(T)
(*6)
=5.0V,
Short Lx at 1Ω resistance, DCOUT voltage which Lx becomes “ Lx=L ” within 1ms
=5.0V,LX=5.0V,V
IN2
=5.0V V
IN2
DCOUT(T)
=0V,V
EN2
DCOUT
= Setting voltage
=open
(*1, *10)
(XCM524AC) - 22 50
(XCM524BC) - 15 33
(*11)
(*3)
- 0.35 0.55 Ω
(*3)
- 0.42 0.67 Ω
1.764 1.800 1.836 V
600 - - mA
1.00 1.40 1.78 V
1020 1200 1380 kHz
120 160 200 mA
- 92 - %
- ±100 - ppm/℃
0.65 - 6.0 V
V
SS
- 0.25 V
- 0.25 0.40 ms
1.0 - 20 ms
0.675 0.900 1.150 V
200 300 450 Ω
NOTE: *1: Including hysteresis width of operating voltage.
*2: EFFI = { ( output voltage×output current ) /( input voltage×input current) }×100 *3: ON resistance (Ω)= (V
- Lx pin measurement voltage) /100mA
IN2
*4: Design value
*5: When temperature is high, a current of approximately 10μA (maximum) may leak.
*6:
Time until it short-circuits DCOUT with GND via 1Ωof resistor from an operational state and is set to Lx=0V from current limit pulse generating.
*7: V
DCOUT(T)
+1.2V<2.7V, V
=2.7V.
IN2
*8: When the difference between the input and the output is small, some cycles may be skipped completely before current maximizes.
If current is further pulled from this state, output voltage will decrease because of P-ch driver ON resistance.
*9: Current limit denotes the level of detection at peak of coil current.
*10: "H"＝V
*11: XCM524A series exclude I
- 1.2V, "L"＝+ 0.1V 〜 - 0.1V
IN2〜VIN2
PFM
and DTY
because those are only for the PFM control’s functions.
LIMIT_PFM
* The electrical characteristics above are when the other channel is in stop.
μA
CIRCUIT
⑦ ⑦ ⑦
⑨
⑧
⑧ ⑦
⑦ ⑦
⑨ ⑨
⑦ ⑩
⑩
−
− ⑮ ⑫
⑦
⑨
⑨ ⑪
⑪ ⑦
⑬
⑬
⑭
9/52
XCM524 Series
■ELECTRICAL CHARACTERISTICS (Continued)
●XCM524xD 2ch (DC/DC BLOCK) V
DCOUT
=1.8V, f
=3.0MHz, Ta=25℃
OSC
PARAMETER SYMBOL CONDITIONS MIN. TYP. MAX. UNITS
Output Voltage V
Operating Voltage Range V
Maximum Output Current I
UVLO Voltage V
DCOUT
2.7 - 6.0 V
IN2
OUT2MAX
UVLO
Supply Current IDD
Stand-by Current I
Oscillation Frequency f
PFM Switching Current I
PFM Duty Limit DTY
Maximum Duty Cycle D
Minimum Duty Cycle D
V
STB
OSC
PFM
LIMIT_PFM
V
MAX
V
MIN
Efficiency EFFI
Lx SW "H" ON Resistance 1 R
Lx SW "H" ON Resistance 2 R
Lx SW "L" ON Resistance 1 R
Lx SW "L" ON Resistance 2 R
Lx SW "H" Leak Current
Current Limit
(*5)
ILeakH V
(*9)
I
Output Voltage
Temperature Characteristics
EN "H" Voltage V
EN "L" Voltage V
EN "H" Current I
EN "L" Current I
LXH1
LXH2
LXL1
LXL2
V
LIM
△
V
DCOUT
(V
・△topr)
DCOUT
ENH
ENL
V
ENH
V
ENL
V
V
V
V
/
Soft Start Time tSS
Latch Time t
Short Protection
Threshold Voltage
CL Discharge R
V
LAT
SHORT
DCHG
V
Test conditions: Unless otherwise stated, V
When connected to external components, V
When connected to external components, V
V Voltage which Lx pin holding “L” level
V
=5.0V,I
IN2=VEN2
IN2=VDCOUT(T)
=5.0V,V
=5.0V,V
V
，
EN2=VIN2
IN2=VEN2
IN2
OUT2
+2.0V,V
=0V,
DCOUT
DCOUT=VDCOUT
=0V,V
EN2
=30mA
(*8)
=1.0V
EN2
×1.1V
(T)
DCOUT=VDCOUT(T)
(*1, *10)
(XCM524AD) - 46 65
(XCM524BD) - 21 35
×1.1V - 0 1.0 μA
When connected to external components, V
IN2=VDCOUT(T)
When connected to external components, V
IN2=VDCOUT(T)
V
EN2=VIN2
IN2=VEN2
IN2=VEN2
When connected to external components, V
EN2=VIN2＝VDCOUT(T)
IN2=VEN2
IN2=VEN2
IN2=VEN2
IN2=VEN2
IN2=VDCOUT
IN2=VEN2
I
=30mA
OUT2
-40℃≦Topr≦85℃
V
DCOUT
Voltage changes Lx to “H” level V
DCOUT
Voltage changes Lx to “L” level
IN2=VEN2
=5.0V,V
IN2
+2.0V,V
+2.0V,V
=(C-1)I
=5.0V, V
=5.0V, V
=5.0V,V
=3.6V,V
=5.0V
=3.6V
=5.0V,V
=5.0V,V
=1.0V, I
EN2
, I
EN2=VIN2
(*11)
=1mA
OUT2
DCOUT=VDCOUT(T)
DCOUT=VDCOUT(T)
(*7)
+1.2V
DCOUT
DCOUT
(*4)
- 0.45 0.66 Ω
(*4)
- 0.52 0.77 Ω
EN2
DCOUT=VDCOUT(T)
, I
=0V,ILX=100mA
=0V,ILX=100mA
=0V,L
=0V - 0.01 1.0 μA
X
=0V, Applied voltage to V
=0V, Applied voltage to V
=5.0V,V
EN2
=0V - 0.1 - 0.1 μA
DCOUT
=0V,V
=0V - 0.1 - 0.1 μA
DCOUT
=100mA
OUT2
(*11)
=1mA
OUT2
- 200 300 %
×0.9V 100 - - %
×1.1V - - 0 %
=100mA
OUT2
(*3)
- 0.35 0.55 Ω
(*3)
- 0.42 0.67 Ω
×0.9V 900 1050 1350 mA
EN2,
(*10)
EN2, (*10)
When connected to external components, V
=0V→V
EN2
V
IN2=VEN2
Short Lx at 1Ω resistance Sweeping V
, I
IN2
=5.0V,V
DCOUT
OUT2
DCOUT
, V
=1mA
=0.8×V
IN2=VEN2
DCOUT(T)
(*6)
=5.0V,
Short Lx at 1Ω resistance, DCOUT voltage which Lx becomes “ Lx=L ” within 1ms
=5.0V,LX=5.0V,V
IN2
=5.0V V
IN2
DCOUT(T)
=0V,V
EN2
DCOUT
= Setting voltage
=open
1.764 1.800 1.836 V
600 - - mA
1.00 1.40 1.78 V
2550 3000 3450 kHz
170 220 270 mA
- 86 - %
- ±100 - ppm/℃
0.65 - 6.0 V
V
- 0.25 V
SS
- 0.32 0.50 ms
1.0 - 20 ms
0.675 0.900 1.150 V
200 300 450 Ω
NOTE: *1: Including hysteresis width of operating voltage.
*2: EFFI = { ( output voltage×output current ) /( input voltage×input current) }×100 *3: ON resistance (Ω)= (V
- Lx pin measurement voltage) /100mA
IN2
*4: Design value
*5: When temperature is high, a current of approximately 10μA (maximum) may leak.
*6:
Time until it short-circuits DCOUT with GND via 1Ωof resistor from an operational state and is set to Lx=0V from current limit pulse generating.
*7: V
DCOUT(T)
+1.2V<2.7V, V
=2.7V.
IN2
*8: When the difference between the input and the output is small, some cycles may be skipped completely before current maximizes.
If current is further pulled from this state, output voltage will decrease because of P-ch driver ON resistance.
*9: Current limit denotes the level of detection at peak of coil current.
*10: "H"＝V
*11: XCM524A series exclude I
- 1.2V, "L"＝+ 0.1V 〜 - 0.1V
IN2〜VIN2
PFM
and DTY
because those are only for the PFM control’s functions.
LIMIT_PFM
* The electrical characteristics above are when the other channel is in stop.
CIRCUIT
⑦ ⑦ ⑦
⑨
μA ⑧
⑧ ⑦
⑦ ⑦
⑨ ⑨
⑦ ⑩
⑩
−
− ⑮ ⑫
⑦
⑨
⑨ ⑪
⑪ ⑦
⑬
⑬
⑭
10/52
X
■ELECTRICAL CHARACTERISTICS (Continued)
●PFM Switching Current (I
1.2MHz (mA)
SETTING VOLTAGE MIN. TYP. MAX.
V
≦1.2Ｖ
DCOUT(T)
1.2V＜V
1.8V≦V
DCOUT(T)
DCOUT(T)
≦1.75Ｖ
3.0MHz (mA)
SETTING VOLTAGE MIN. TYP. MAX.
V
≦1.2Ｖ
DCOUT(T)
1.2V＜V
1.8V≦V
DCOUT(T)
DCOUT(T)
≦1.75Ｖ
●Measuring Maximum I
f
1.2MHz 3.0MHz
OSC
(C-1) V
DCOUT(T)
+0.5V V
Minimum operating voltage is 2.7V
Although when V
DCOUT(T)
=1.2V, f
●Soft-Start Time Chart (XCM524xC/ XCM524xD Series Only)
PRODUCT SERIES f
XCM524AC
XCM524BC
XCM524xD
) by Oscillation Frequency and Output Voltage
PFM
140 180 240
130 170 220
120 160 200
190 260 350
180 240 300
170 220 270
Limit, V
PFM
DCOUT(T)
OSC
Volta ge
IN2
+1.0V
=1.2MHz, (C-1)=1.7V the (C-1) becomes 2.7V because of the minimum operating voltage 2.7V.
OUTPUT VOLTAGE MIN. TYP. MAX.
OSC
1.2MHz
1.2MHz
1.2MHz
1.2MHz
1.2MHz
1.2MHz
3.0MHz
3.0MHz
0.8V≦V
1.5V≦V
1.8V≦V
2.5V≦V
0.8V≦V
2.5V≦V
0.8V≦V
1.8V≦V
DCOUT(T)
DCOUT(T)
DCOUT(T)
DCOUT(T)
DCOUT(T)
DCOUT(T)
DCOUT(T)
DCOUT(T)
<1.5V
<1.8V
<2.5V
≦4.0V
<2.5V
≦4.0V
<1.8V
≦4.0V
-
-
-
-
-
-
-
-
250μs 400μs 320μs 500μs 250μs 400μs 320μs 500μs 250μs 400μs 320μs 500μs 250μs 400μs 320μs 500μs
CM524
Series
■TYPICAL APPLICATION CIRCUIT
Rpull-up
V
IN CIN2
VROUTVDOUT
CL1
CIN1
EN2
VDCOUT
NC
VIN1
EN2
AGND
12
11
103
9
8
7
CL2
1
VDOUT VROUT
2
VSS
Cd
4
5
6
Cd
VIN2
PGND
Lx
DCOUT
L
●DC/DC BLOCKf
C
: 1μF (Ceramic)
IN1
C
L1
: 1μF (Ceramic)
=3.0MHz
OSC
L : 1.5μH (NR3015 TAIIYO YUDEN)
: 4.7μF (Ceramic)
C
IN2
: 10μF (Ceramic)
C
L2
●DC/DC BLOCKf
C
: 1μF (Ceramic)
IN1
: 1μF (Ceramic)
C
L1
=1.2MHz
OSC
L : 4.7μH (NR4018 TAIIYO YUDEN)
: 4.7μF (Ceramic)
C
IN2
C
L2
: 10μF (Ceramic)
11/52
■
XCM524 Series
OPERATIONAL EXPLANATION
●Voltage Regulator BLOCK
The voltage divided by resistors R1 & R2 is compared with the internal reference voltage by the error amplifier. The P-channel MOSFET which is connected to the V at the V
●Detector Function with the XC524 Series
The series' detector function monitors the voltage divided by resistors R3 & R4, which are connected to the VR V
IN1 pin or the VSEN pin, as well as monitoring the voltage of the internal reference voltage source via the comparator. The
VDSEN pin has options. A 'High' or 'Low' signal level can be output from the VD below the detect voltage. The VD output logic has options. As VD
of about 220kΩis needed to achieve a voltage output.
Because of hysteresis at the detector function, output at the VD above the release voltage (105% of the detect voltage). By connecting the Cd pin to a capacitor, the XCM524 series can apply a delay time to VDOUT voltage when releasing voltage.
The delay time can be calculated from the internal resistance, Rdelay (500kΩ fixed) and the value of Cd as per the following
equation.
pin is controlled & stabilized by a system of negative feedback.
ROUT
Delay Time = Cd x Rdelay x 0.7 …(1)
Delay Time
Rdelay standard : 300 ~ 700kΩ TYP : 500kΩ
Cd DELAY TIME (TYP.)
0.01μF
0.022μF
0.047μF
0.1μF
0.22μF
0.47μF 1μF
<Low ESR Capacitor> With the XCM524 series, a stable output voltage is achievable even if used with low ESR capacitors, as a phase
compensation circuit is built-in. The output capacitor (CL1) should be connected as close to V stable phase compensation. Also, please connect an input capacitor (C
Output Capacitor Chart
* The release delay time values above are calculated by using the formula (1).
*1: The release delay time is influenced by the delay capacitance Cd.
V
0.9 ~1.2V 1.3 ~ 1.7V 1.8 ~ 5.1V
ROUT
pin is then driven by the subsequent output signal. The output voltage
ROUT
OUT pin or the
OUT pin when the VD pin voltage level goes
OUT is an open-drain N-channel output, a pull-up resistor
OUT pin will invert when the detect voltage level increases
DELAY TIME (MIN.～MAX.)
3.5 ms 2.1 ~ 4.9 ms
7.7 ms 4.62 ~ 10.8 ms
16.5 ms 9.87 ~ 23.0 ms
35 ms 21.0 ~ 49.0 ms
77 ms 46.2 ~ 108.0 ms
165 ms 98.7 ~ 230.0 ms
350 ms 210.0 ~ 490.0 ms
pin and VSS pin to obtain
ROUT
IN1) of 1.0μF between the VIN1 pin and the VSS pin.
CL1
<Current Limit, Short-Circuit Protection> The XCM524 series’ fold-back circuit operates as an output current limiter and a short protection of the output pin. When the
load current reaches the current limit level, the fixed current limiter circuit operates and output voltage drops. When the output pin is shorted to the V

SS
≧4.7μF ≧2.2μF ≧1.0μF
level, current flows about 50mA.
12/52
X
CM524
Series
■OPERATIONAL EXPLANATION (Continued)
●DC/DC BLOCK
The DC/DC block of the XCM524 series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator, phase compensation circuit, output voltage adjustment resistors, P-channel MOSFET driver transistor, N-channel MOSFET switch transistor for the synchronous switch, current limiter circuit, UVLO circuit and others. (See the block diagram
above.) The series ICs compare, using the error amplifier, the voltage of the internal voltage reference source with the feedback voltage from the DCOUT pin through split resistors, R1 and R2. Phase compensation is performed on the resulting error amplifier output, to input a signal to the PWM comparator to determine the turn-on time during PWM operation. The PWM comparator compares, in terms of voltage level, the signal from the error amplifier with the ramp wave from the ramp wave circuit, and delivers the resulting output to the buffer driver circuit to cause the Lx pin to output a switching duty cycle. This process is continuously performed to ensure stable output voltage. The current feedback circuit monitors the P-channel MOS driver transistor current for each switching operation, and modulates the error amplifier output signal to provide multiple feedback signals. This enables a stable feedback loop even when a low ESR capacitor such as a ceramic capacitor is used ensuring stable output voltage.
<Reference Voltage Source> The reference voltage source provides the reference voltage to ensure stable output voltage of the DC/DC converter.
<Ramp Wave Circuit> The ramp wave circuit determines switching frequency. The frequency is fixed internally and can be selected from 1.2MHz or
3.0MHz. Clock pulses generated in this circuit are used to produce ramp waveforms needed for PWM operation, and to synchronize all the internal circuits.
<Error Amplifier> The error amplifier is designed to monitor output voltage. The amplifier compares the reference voltage with the feedback voltage divided by the internal split resistors, R1 and R2. When a voltage is lower than the reference voltage is fed back, the output voltage of the error amplifier increases. The gain and frequency characteristics of the error amplifier output are fixed internally to deliver an optimized signal to the mixer.
<Current Limit> The current limiter circuit of the XCM524series monitors the current flowing through the P-channel MOS driver transistor connected to the Lx pin, and features a combination of the current limit mode and the operation suspension mode.
①When the driver current is greater than a specific level, the current limit function operates to turn off the pulses from the Lx pin
at any given timing.
②When the driver transistor is turned off, the limiter circuit is then released from the current limit detection state. ③At the next pulse, the driver transistor is turned on. However, the transistor is immediately turned off in the case of an over
current state.
④When the over current state is eliminated, the IC resumes its normal operation. The IC waits for the over current state to end by repeating the steps ①through ③. If an over current state continues for a
few ms and the above three steps are repeatedly performed, the IC performs the function of latching the OFF state of the P-channel driver transistor, and goes into operation suspension mode. Once the IC is in suspension mode, operations can be resumed by either turning the IC off via the CE/MODE pin, or by restoring power to the V not mean a complete shutdown, but a state in which pulse output is suspended; therefore, the internal circuitry remains in operation. The current limit of the XCM524 series can be set at 1050mA at typical. Besides, care must be taken when laying out the PC Board, in order to prevent miss-operation of the current limit mode. Depending on the state of the PC Board, latch time may become longer and latch operation may not work. In order to avoid the effect of noise, the board should be laid out so that input capacitors are placed as close to the IC as possible.
Limit＜#ms
Limit<数ms
Limit＞#ms
Limit>数ms
ILx
V
DCOUT
Lx
VEN2
VIN2
pin. The suspension mode does
IN2
Current Limit LEVEL
0mA
VSS
Restart
13/52
XCM524 Series
■OPERATIONAL EXPLANATION (Continued)
<Short-Circuit Protection>
The short-circuit protection circuit monitors the internal R1 and R2 divider voltage from the DCOUT pin. In case where output is accidentally shorted to the Ground and when the FB point voltage decreases less than half of the reference voltage (Vref) and a current more than the I turn off and to latch the P-channel MOS driver transistor. In latch state, the operation can be resumed by either turning the IC off and on via the EN2 pin, or by restoring power supply to the V
When sharp load transient happens, a voltage drop at the DCOUT pin is propagated to FB point through C circuit protection may operate in the voltage higher than 1/2 V
<UVLO Circuit>
When the V
IN2 pin voltage becomes 1.4V or lower, the P-channel output driver transistor is forced OFF to prevent false pulse
output caused by unstable operation of the internal circuitry. When the V operation takes place. By releasing the UVLO function, the IC performs the soft start function to initiate output startup operation. The soft start function operates even when the VIN pin voltage falls momentarily below the UVLO operating voltage. The UVLO circuit does not cause a complete shutdown of the IC, but causes pulse output to be suspended; therefore, the internal circuitry remains in operation.
<PFM Switch Current> In the PFM control operation, until coil current reaches to a specified level (I case, on-time (t
t
= L×I
ON
PFM
) that the P-ch MOSFET is kept on can be given by the following formula.
ON
/(V
IN2-VDCOUT
) →I
PFM
①
<PFM duty Limit> In the PFM control operation, the PFM duty limit (DTY duty increases (e.g. the condition that the step-down ratio is small), it’s possible for P-ch MOSFET to be turned off even when coil current doesn’t reach to I
PFM
. →I
                                         
PFM
①
14/52
flows to the driver transistor, the short-circuit protection quickly operates to
LIM
pin.
IN2
voltage.
OUT
pin voltage becomes 1.8V or higher, switching
IN2
) , the IC keeps the P-ch MOSFET on. In this
PFM
) is set to 200% (TYP.). Therefore, under the condition that the
PFM Duty Limit
I
② I
PFM
PFM
LIMIT_PFM
②
, as a result, short
FB
X
CM524
Series
■OPERATIONAL EXPLANATION (Continued)
High Speed Discharge>
<C
L
XCM524 series can quickly discharge the electric charge at the output capacitor (CL2) when a low signal to the CE pin which enables a whole IC circuit put into OFF state, is inputted via the N-channel MOS switch located between the L pin. When the IC is disabled, electric charge at the output capacitor (C malfunction. Discharge time of the output capacitor (C
) is set by the CL auto-discharge resistance (R) and the output capacitor
L
) is quickly discharged so that it may avoid application
L
(CL). By setting time constant of a CL auto-discharge resistance value [R] and an output capacitor value (CL2) as
τ(τ=C x R), discharge time of the output voltage after discharge via the N channel transistor is calculated by the following
formula.
-t /
V = V
DCOUT(T)
τ
×e
or t = τLn ( V
DCOUT(T)
/V)
V : Output voltage after discharge, V
: Output voltage after discharge
DCOUT(T)
t: Discharge time
τ: C×R C = Capacitance of Output capacitor（C
auto-discharge resistance
R = C
L
）
L2
pin and the VSS
X
100
） e u
l a
V e
v
i
t a
l e
R （
e g a
t
l o
V t
u p
t u
O
90
e
80
u
l a
V
70
e g
60
a
t
l o
50
V g
n
i
40
t
t e
30
S =
20
0 0 1
10
0
0 102030405060708090100
CL=10uF
CL=20uF
CL=50uF
■NOTE ON USE
When the DC/DC converter and the VR are connected as V
DCOUT=VIN1
1. When larger value is used in DC/DC output capacitor CL2, the larger value is also used in C noted that when C
capacitance of the VR is getting large, an inrush current increases at VR start-up, DC/DC short circuit
L2
protection starts to operate, as a result, the IC may happen to stop.
DCOUT(1V/div)
IIN2(500mA/div)
VROUT(1V/div)
short-circuit protection to start
短絡保護動作
EN2(5V/div)
50us/div
* VR inrush current I
start, as a result, the IC may happen to stop.
The left waver forms are taken at C
contrast to the recommended 1.0μF).
, the following points should be noted.
makes DC/DC short-circuit protection to
IN1
as in proportional. Please be
L1
=10μ, CL2=10μF(in
L1
15/52
XCM524 Series
■NOTE ON USE (Continued)
<VDR BLOCK>
1. Please use this IC within the stated absolute maximum ratings. The IC is liable to malfunction should the ratings be exceeded.
2. Where wiring impedance is high, operations may become unstable due to noise and/or phase lag depending on output current. Especially, V
3. Please wire the input capacitor (C
Care shall be taken for capacitor selection to ensure stability of phase compensation from the point of ESR influence.
<DC/DC BLOCK>
1. The XCM524 series is designed for use with ceramic output capacitors. If, however, the potential difference is too large between the input voltage and the output voltage, a ceramic capacitor may fail to absorb the resulting high switching energy and oscillation could occur on the output. If the input-output potential difference is large, connect an electrolytic capacitor in parallel to compensate for insufficient capacitance.
2. Spike noise and ripple voltage arise in a switching regulator as with a DC/DC converter. These are greatly influenced by
external component selection, such as the coil inductance, capacitance values, and board layout of external components. Once the design has been completed, verification with actual components should be done.
3. As a result of input-output voltage and load conditions, oscillation frequency goes to 1/2, 1/3, and continues, then a ripple
may increase.
4. When input-output voltage differential is large and light load conditions, a small duty cycle comes out. After that, 0%duty
cycle may continue in several periods.
5. When input-output voltage differential is small and heavy load conditions, a large duty cycle comes out and may
continues100% duty cycle in several periods.
6. With the IC, the peak current of the coil is controlled by the current limit circuit. Since the peak current increases when
dropout voltage or load current is high, current limit starts operation, and this can lead to instability. When peak current becomes high, please adjust the coil inductance value and fully check the circuit operation. In addition, please calculate the peak current according to the following formula:
Ipk =(V
L：Coil Inductance Value
f
7. When the peak current which exceeds limit current flows within the specified time, the built-in P-channel MOS driver transistor turns off. During the time until it detects limit current and before the P-channel built-in transistor can be turned off, the current for limit current flows; therefore, care must be taken when selecting the rating for the external components such as a coil.
8. Depending on the state of the PC Board, latch time may become longer and latch operation may not work. In order to avoid
the effect of noise, the board should be laid out so that input capacitors are placed as close to the IC as possible.
9. Use of the IC at voltages below the recommended voltage range may lead to instability.
10. This IC should be used within the stated absolute maximum ratings in order to prevent damage to the device.
11. When the IC is used in high temperature, output voltage may increase up to input voltage level at no load because of the
leak current of the P-channel MOS driver transistor.
IN2-VDCOUT
：Oscillation Frequency
OSC
and VSS wiring should be taken into consideration for reinforcement.
IN1
) and the output capacitor (CL1) as close to the IC as possible.
IN1
)×OnDuty/(2×L×f
OSC
) + I
OUT2
16/52
Loading...
+ 36 hidden pages
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use