XC9141/XC9142 Series
ETR04018-003d
Load Disconnection Function, 0.8A Step-up DC/DC Converters
☆Green Operation compatible
■GENERAL DESCRIPTION
XC9141/XC9142 series are synchronous step-up DC/DC converters with a 0.3Ω N-channel driver transistor and a 0.3Ω
synchronous P-channel switching transistor built-in. A highly efficient and stable current can be supplied up to 0.8A by reducing
ON resistance of the built-in transistors.
The series are able to start operation under the condition which has 0.9V input voltage to generate 3.3V output voltage with a
100Ω load resistor, suitable for mobile equipment using only one Alkaline battery or one Nickel metal hydride battery.
The output voltage can be set from 1.8V to 5.5V (±2.0%) in steps of 0.1V. With the built-in oscillator, either 1.2MHz or 3.0MHz can
be selected for suiting to your particular application.
During the devices enter stand-by mode, A, D types prevent the application malfunction by C L Discharge Function which can
quickly discharge the electric charge at the output capacitor (CL). B, E types is able to drive RTC etc. by Bypass Switch Function
to maintain continuity between the input and output. C, F types is able to connect in output voltage OR circuit with other power
supplies by Load Disconnection Function which breaks continuity between the input and output.
■APPLICATIONS
■FEATURES
●Portable equipment
Input Voltage Range
Fixed Output Voltage
Oscillation Frequency
Input Current
Output Current
●Beauty & health equipment
●Wearable devices
●Game & Hobby
●PC Peripherals
●Devices with 1~3 Alkaline,
Control Mode Selection
1~3 Nickel Hydride, 1 Lithium and 1 Li-ion
Load Transient Response
Protection Circuits
Functions
Output Capacitor
Operating Ambient Temperature
Package
Environmentally Friendly
L=4.7μH
Lx
CE
VOUT
VOUT
CL=10μF
CE
VB AT
BAT
CIN =10μF
■TYPICAL PERFORMANCE
CHARACTERISTICS
GND
:XC9141A33C / XC9142A33C
L=4.7μH(LQH5BPN4R7NT0L)
:
CIN=10μF(GRM188R60J106M),CL=10μF(GRM188R60J106M)
:
100
:
90
:
80
:
70
:
60
V BAT =0.9V
:
V BAT =1.2V
50
:
V BAT =1.8V
40
V BAT =2.5V
:
Efficiency : EFFI [%]
■TYPICAL APPLICATION CIRCUIT
: 0.65V ~ 6.0V
: 1.8V ~ 5.5V (0.1V increments)
: 1.2MHz, 3.0MHz
: 0.8A
: 500mA @VOUT=5.0V, VBAT=3.3V
330mA @VOUT=3.3V, VBAT =1.8V
: PWM (XC9141)
PWM/PFM (XC9142)
: 100mV@VOUT=3.3V, VBAT =1.8V,
IOUT=1mA→200mA (tr=5μs)
: Over-current limit
Integral latch method (D,E,F type)
Output short-circuit protection (D,E,F type)
: Soft-start
Load Disconnection (A,C,D,F type)
CL Auto Discharge (A,D type)
Bypass Switch (B,E type)
: Ceramic Capacitor
: -40℃ ~ 85℃
: SOT-25, USP-6C, WLP-6-01
: EU RoHS Compliant, Pb Free
30
20
solid line : XC9141
dotted line : XC9142
10
0
0.1
1
10
100
Output Current : IOUT [mA]
1000
1/32
XC9141/XC9142 Series
■BLOCK DIAGRAM
●A type
Lx
CFB
Load disconnect
Controller
Phase
Compensation
RFB1
FB
PWM/PFM
Controller Logic
RFB2
Vref with
Soft Start
VOUT
PWM
comparator
Error Amp.
RAMP Wave
Generator
CL
Discharge
Buffer
Driver
GND
OSC
CE Controller
Logic
CE
VOUT
Current sense
VDD
VOUT
BAT
VDD MAX
* Diodes inside the circuits are ESD protection diodes and parasitic diodes.
* XC9141 series chooses only PWM control.
●B type
Lx
CFB
Load disconnect
Controller
Phase
Compensation
RFB1
VOUT
PWM
comparator
Error Amp.
FB
PWM/PFM
Controller Logic
RFB2
Vref with
Soft Start
RAMP Wave
Generator
Buffer
Driver
GND
OSC
CE Controller
Logic
CE
VOUT
Current sense
Bypass SW
VOUT
VDD
VDD MAX
BAT
* Diodes inside the circuits are ESD protection diodes and parasitic diodes.
* XC9141 series chooses only PWM control.
●C type
Lx
CFB
Load disconnect
Controller
Phase
Compensation
RFB1
Error Amp.
FB
Current sense
CE
VOUT
PWM
comparator
PWM/PFM
Controller Logic
RFB2
Vref with
Soft Start
VOUT
RAMP Wave
Generator
Buffer
Driver
GND
OSC
CE Controller
Logic
VDD
VOUT
VDD MAX
* Diodes inside the circuits are ESD protection diodes and parasitic diodes.
2/32
BAT
XC9141/XC9142
Series
■BLOCK DIAGRAM (Continued)
●D type
Lx
CFB
Phase
Compensation
RFB1
PWM
comparator
Error Amp.
FB
PWM/PFM
Controller Logic
RFB2
Vref with
Soft Start
RAMP Wave
Generator
Load disconnect
Controller
Current sense
Short-circuit protection
Latch Timer
VOUT
CL
Discharge
Buffer
Driver
GND
OSC
CE Controller
Logic
CE
VOUT
VDD
VOUT
BAT
VDD MAX
* Diodes inside the circuits are ESD protection diodes and parasitic diodes.
* XC9141 series chooses only PWM control.
●E type
Lx
CFB
Phase
Compensation
RFB1
PWM
comparator
Error Amp.
FB
PWM/PFM
Controller Logic
RFB2
Vref with
Soft Start
RAMP Wave
Generator
Load disconnect
Controller
Current sense
Short-circuit protect ion
Latch Timer
VOUT
Buffer
Driver
GND
OSC
CE Controller
Logic
CE
VOUT
Bypass SW
VOUT
VDD
VDD MAX
BAT
* Diodes inside the circuits are ESD protection diodes and parasitic diodes.
* XC9141 series chooses only PWM control.
●F type
Lx
CFB
Phase
Compensation
RFB1
Error Amp.
FB
PWM
comparator
PWM/PFM
Controller Logic
RFB2
Vref with
Soft Start
CE
RAMP Wave
Generator
Load disconnect
Controller
Current sense
Short-circuit protect ion
Latch Timer
VOUT
VOUT
Buffer
Driver
GND
OSC
CE Controller
Logic
VDD
VOUT
VDD MAX
BAT
* Diodes inside the circuits are ESD protection diodes and parasitic diodes
3/32
XC9141/XC9142 Series
■PRODUCT CLASSIFICATION
●Ordering Information
XC9141①②③④⑤⑥-⑦ PWM control
DESIGNATOR
ITEM
SYMBOL
DESCRIPTION
A
①
B
Type
D
Refer to Selection Guide
E
Output Voltage
(A,B Type)
Output Voltage
(D,E Type)
②③
④
22 ~ 55
Oscillation Frequency
⑤⑥-⑦(*1)
(*1)
18 ~ 55
Package (Order Unit)
Output voltage options
e.g. 1.8V → ②=1, ③=8
Output voltage options
e.g. 2.5V → ②=2, ③=5
C
1.2MHz
D
3.0MHz
MR-G
SOT-25 (3,000pcs/Reel)
ER-G
USP-6C (3,000pcs/Reel)
0R-G
WLP-6-01(5,000pcs/Reel)
The ”-G” suffix indicates that the products are Halogen and Antimony free as well as being fully EU RoHS compliant.
●Selection guides
TYPE
Purpose
CL
Discharge
Load Disconnection
Yes
A
D
B
E
4/32
Bypass Mode
at CE=”L”
-
Current
Limit
Yes
(without latch)
Yes
(with integral latch)
Yes
(without latch)
Yes
(with integral latch)
Short
Protection
Yes
Yes
Stand-by Options
at CE=”L”
Complete
Output Disconnect
Input-to-Output
Bypass
XC9141/XC9142
Series
■PRODUCT CLASSIFICATION (Continued)
XC9142①②③④⑤⑥-⑦ PWM/PFM automatic switching control
DESIGNATOR
ITEM
SYMBOL
DESCRIPTION
A
B
①
C
Type
D
Refer to Selection Guide
E
F
Output Voltage
(A,B,C Type)
Output Voltage
(D,E,F Type)
②③
(*1)
④
Oscillation Frequency
⑤⑥-⑦(*1)
Package (Order Unit)
18 ~ 55
22 ~ 55
Output voltage options
e.g. 1.8V → ②=1, ③=8
Output voltage options
e.g. 2.5V → ②=2, ③=5
C
1.2MHz
D
3.0MHz
MR-G
SOT-25 (3,000pcs/Reel)
ER-G
USP-6C (3,000pcs/Reel)
0R-G
WLP-6-01(5,000pcs/Reel)
The ”-G” suffix indicates that the products are Halogen and Antimony free as well as being fully EU RoHS compliant.
●Selection guides
TYPE
Purpose
CL
Discharge
Load Disconnection
Yes
A
D
B
E
C
F
Bypass Mode
at CE=”L”
-
VOUT OR
Connection
-
Current
Limit
Yes
(without latch)
Yes
(with integral latch)
Yes
(without latch)
Yes
(with integral latch)
Yes
(without latch)
Yes
(with integral latch)
Short
Protection
Yes
Yes
Yes
Stand-by Options
at CE=”L”
Complete
Output Disconnect
Input-to-Output
Bypass
Complete
Output Disconnect
5/32
XC9141/XC9142 Series
■PIN CONFIGURATION
Lx
VOUT
5
4
1
CE
2
3
GND
BAT
VOUT 6
1 BAT
GND 4
Lx 5
2 GND
Lx 5
2 GND
VOUT 6
1 BAT
3 CE
GND 4
WLP-6-01
(BOTTOM VIEW)
USP-6C
(BOTTOM VIEW)
SOT-25
(TOP VIEW)
3 CE
*The dissipation pad for the USP-6C package should be solder-plated in recommended mount pattern and
metal masking so as to enhance mounting strength and heat release. If the pad needs to be connected to other
pins, it should be connected to the GND (No.2, 4) pin.
■PIN ASSIGNMENT
SOT-25
PIN NUMBER
USP-6C
WLP-6-01
1
2
3
4
5
-
3
2
1
6
5
4
3
2
1
6
5
4
PIN NAME
FUNCTIONS
CE
GND
BAT
VOUT
Lx
GND
Chip Enable
Ground
Power Input
Output Voltage
Switching
Ground
■FUNCTION CHART
PIN NAME
SIGNAL
STATUS
L
Stand-by
H
Active
CE
* Do not leave the CE pin open.
■ABSOLUTE MAXIMUM RATINGS
Ta=25℃
PARAMETER
SYMBOL
RATINGS
UNITS
BAT Pin Voltage
VBAT
-0.3 ~ 7.0
V
Lx Pin Voltage
VLx
-0.3 ~ 7.0
V
VOUT Pin Voltage
VOUT
-0.3 ~ 7.0
V
CE Pin Voltage
VCE
-0.3 ~ 7.0
V
600 (40mm x 40mm
SOT-25
Power
Dissipation
USP-6C
760 (JESD51-7 基板) (*1)
Pd
1000 (40mm x 40mm 標準基板) (*1)
mW
1250 (JESD51-7 基板) (*1)
700 (40mm x 40mm 標準基板) (*1)
WLP-6-01
Operating Ambient Temperature
Topr
-40 ~ 85
℃
Storage Temperature
Tstg
-55 ~ 125
℃
* GND are standard voltage for all of the voltage.
(*1)
標準基板) (*1)
This power dissipation figure shown is PCB mounted and is for reference only.
Please refer to PACKAGING INFORMATION for the mounting condition.
6/32
XC9141/XC9142
Series
■ELECTRICAL CHARACTERISTICS
Ta=25℃
PARAMETER
SYMBOL
Input Voltage
VBAT
CONDITIONS
Voltage to start oscillation while
MIN.
TYP.
MAX.
UNITS
CIRCUIT
-
-
6.0
V
①
V
⑤
Output Voltage
VOUT
Operation Start Voltage
VST1
RL=1kΩ
-
-
0.90
V
①
Operation Hold Voltage
VHLD
RL=1kΩ
-
0.65
-
V
①
fOSC=1.2MHz
-
17.0
30.0
μA
③
fOSC=3.0MHz
-
26.0
40.0
fOSC=1.2MHz
-
1.500
mA
③
fOSC=3.0MHz
-
3.000
VBAT= VOUT(T)×0.5
fOSC=1.2MHz
1.02
1.20
1.38
IOUT=100mA
MHz
①
fOSC=3.0MHz
2.40
3.00
3.60
VBAT=1.2V,
fOSC=1.2MHz
85
93
98
VOUT= VOUT(T)-0.2V
%
⑤
fOSC=3.0MHz
88
93
98
-
-
0
%
⑤
-
165
230
mA
①
-
86(*3)
-
Quiescent Current
(XC9142)
Supply Current
Oscillation Frequency
Maximum Duty Cycle
Minimum Duty Cycle
PFM Switching Current
Efficiency
(XC9142)
Efficiency
Iq
IDD
fOSC
DMAX
DMIN
IPFM
EFFI
EFFI
VOUT=VOUT(T) ×1.03→VOUT(T) ×0.97
VOUT=VBAT= VOUT(T)+0.5V
VOUT=VBAT= VOUT(T)-0.2V
VOUT=VBAT= VOUT(T)+0.5V
VBAT=1.5V,
RL is selected with VOUT(T), Refer to Table 1.
VBAT= VOUT(T)×0.6,
RL is selected with VOUT(T), Refer to Table 1.
VBAT= VOUT(T)×0.6, IOUT= 100mA
A,B,D,E
Stand-by Current
ISTB
VBAT=VLx=6.0V,VCE=0.0V
(*1)
Type
C,F Type
Lx SW "Pch" ON
Resistance
Lx SW "Nch" ON
Resistance
Lx SW”H” Leakage
Current
Lx SW”L” Leakage
Current (XC9142C/F)
Current Limit
Integral Latch Time
(D,E,F Type)
Latch Release Voltage
(D,E,F Type)
RLXP
VBAT=VLx= 6.0V, IOUT=200mA
RLXN
ILXLH
VBAT=6.0V, VCE=0.0V,
VLx=6.0V(*1)
Type
90(*3)
-
-
0.0
1.0
-
1.0
2.4
-
0.3(*2)
-
Ω
④
-
0.3(*3)
-
Ω
①
-
0.0
1.0
μA
⑦
μA
⑧
⑦
⑧
C,F Type
-
0.0
1.0
μA
②
A
⑥
fOSC=1.2MHz
45
300
725
μs
⑥
fOSC=3.0MHz
25
100
365
μs
⑥
0.9
1.2
1.5
V
①
-
VBAT(*3)
-
V
①
VBAT=0.0V,VCE=0.0V,VLx=0.0V,VOUT=6.0V
ILIM
VBAT= VOUT(T)-0.2V, RLx=1Ω
tLAT
①
-
A,B,D,E
ILXLL
VBAT= VOUT(T)-0.2V, RLx=1Ω,
①
%
Time from current limit start
to stop Lx oscillation
After the integral latch was operated,
VLAT_R
RL is selected with VOUT(T), Refer to Table 1
VBAT=VOUT(T)-0.2V→0.9V
Short-circuit Protection
Threshold Voltage
VSHORT
VBAT=VOUT(T)-0.2V, RL=0Ω
(D,E,F Type)
7/32
XC9141/XC9142 Series
■ELECTRICAL CHARACTERISTICS (Continued)
PARAMETER
SYMBOL
CONDITIONS
MIN.
TYP.
MAX.
0.6
1.0
2.5
UNITS
CIRCUIT
ms
⑤
VBAT= VOUT(T)×0.6,
VOUT=VOUT(T)× 0.9,
Soft-Start Time
tSS
fOSC=1.2MHz
After "H" is fed to CE,
the time by when clocks are
fOSC=3.0MHz
0.2
0.5
1.0
generated at Lx pin.
CL Discharge Resistance
(A,D Type)
Bypass SW Resistance
(B,E Type)
RDCHG
VBAT= 3.3V,VOUT=3.3V,VCE=0.0V
100
180
400
Ω
②
RBSW
VBAT= 3.3V,VOUT=0.0V,VCE=0.0V
100
180
400
Ω
②
0.80
-
6.00
V
⑤
GND
-
0.20
V
⑤
VOUT= VOUT(T)-0.15V, Applied voltage to VCE,
CE ”H” Voltage
VCEH
CE ”L” Voltage
VCEL
CE ”H” Current
ICEH
VBAT=6.0V,VOUT=6.0V, VLx=6.0V, VCE=6.0V
-0.1
-
0.1
μA
②
CE ”L” Current
ICEL
VBAT=6.0V,VOUT=6.0V, VLx=6.0V, VCE=0.0V
-0.1
-
0.1
μA
②
Voltage changes Lx to be generated.
VOUT= VOUT(T)-0.15V, Applied voltage to VCE,
Voltage changes Lx to“H” level.
VOUT(T) = Target voltage
Test Conditions: unless otherwise stated, VBAT=1.5V, Vce=3.3V, Lx: OPEN, RLx=56Ω
(*1)
XC9141A/D,XC9142A/D,XC9142C/F type: VOUT=0V,
XC9141B/E,XC9142B/E type: VOUT=OPEN
(*2)
Design value for the XC9142C/F type.
(*3)
Designed value
Table 1. External Components RL Table
VOUT(T)
RL
UNITS:V
UNITS:Ω
1.8≦VOUT(T)
< Circuit No.④ >
V
VOUT
Lx
VOUT
Lx
A
A
BAT
BAT
CE
GND
< Circuit No.⑤ >
< Circuit No.⑥ >
Wave Form Measure Point
Wave Form Measure Point
Wave Form Measure Point
VOUT
Lx
VOUT
Lx
RLx=1Ω
RLx=56Ω
BAT
BAT
CE
GND
< Circuit No.⑧ >
VOUT
Lx
IST B
A
ILXLH
CE
GND
< Circuit No.⑦ >
A
BAT
CE
VOUT
Lx
IST B
A
GND
10/32
IOUT
CE
GND
ILXLH
A
BAT
CE
GND
XC9141/XC9142
Series
■TYPICAL APPLICATION CIRCUIT
L
VBA T
VOUT
VOUT
Lx
BAT
CE
CE
GN D
CL
CIN
【Typical Examples】fOSC=1.2MHz
L
CL(*1)
MANUFACTURER
PRODUCT NUMBER
VALUE
murata
LQH5BPN4R7NT0L
4.7μH
TDK
LTF5022T-4R7N2R0-LC
4.7μH
Coilcraft
XFL4020-472MEC
4.7μH
murata
GRM188R60J106ME84
10μF/6.3V(*2)
murata
GRM188D71A106MA73
10μF/10V(*2)
MANUFACTURER
PRODUCT NUMBER
VALUE
TDK
LTF5022T-2R2N3R2-LC
2.2μH
Coilcraft
XFL4020-222MEC
2.2μH
murata
GRM188R60J106ME84
10μF/6.3V(*2)
murata
GRM188D71A106MA73
10μF/10V(*2)
【Typical Examples】fOSC=3.0MHz
L
CL(*1)
【Typical Examples】fOSC=1.2MHz, fOSC=3.0MHz
CIN(*1)
MANUFACTURER
PRODUCT NUMBER
VALUE
murata
GRM188R60J106ME84
10μF/6.3V
murata
GRM188D71A106MA73
10μF/10V
(*1)
Select components appropriate to the usage conditions (ambient temperature, input & output voltage).
While selecting a part, please concern about capacitance reduction and voltage durability.
(*2)
In the case of fosc=1.2MHz: If VOUT(T)≧3.5V and the load current rises above 200mA, use two or more in a parallel connection.
In the case of fosc=3.0MHz: If VBAT≧2V, VOUT(T)≧3.5V and the load current rises above 200mA, use two or more in a parallel connection.
For the actual load capacitance, use a ceramic capacitor that ensures a capacitance equivalent to or greater than the GRM188R60J106ME84
(Murata).
If using tantalum or low ESR electrolytic capacitors please be aware that ripple voltage will be higher due to the larger ESR (Equivalent Series
Resistance) values of those types of capacitors. Please also note that the IC’s operation may become unstable with such capacitors so that
we recommend to test on the board before usage.
If using electrolytic capacitor for the CL, please connect a ceramic capacitor in parallel.
11/32
XC9141/XC9142 Series
■OPERATIONAL EXPLANATION
The XC9141/XC9142 series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator, phase compensation
circuit, N-channel driver transistor, P-channel synchronous rectification switching transistor and current limiter circuit.
Lx
CFB
Load disconnect
Controller
Phase
Compensation
RFB1
Error Amp.
FB
RFB2
CE
VOUT
PWM
comparator
PWM/PFM
Controller Logic
Vref with
Soft Start
VOUT
Current sense
RAMP Wave
Generator
CL
Discharge
Buffer
Driver
GND
OSC
CE Controller
Logic
VDD
Bypass SW
VOUT
VDD MAX
BAT
BLOCK DIAGRAM
The error amplifier compares the internal reference voltage with the resistors RFB1 and RFB2. Phase compensation is performed on the resulting
error amplifier output, to input a signal to the PWM comparator to determine the turn-on time of the N-channel driver transistor 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 N-channel driver transistor’s turn-on 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.
The reference voltage forms a reference that is used to stabilize the output voltage of the IC.
After “H” level is fed to CE pin, the reference voltage connected to the error amp increases linearly during the soft start interval. This allows the
voltage divided by the internal RFB1 and RFB2 resistors and the reference voltage to be controlled in a balanced manner, and the output voltage
rises in proportion to the rise in the reference voltage. This operation prevents rush input current and enables the output voltage to rise smoothly.
The ramp wave circuit determines switching frequency. The frequency is fixed internally at 1.2MHz/3.0MHz. The Clock generated is used to
produce ramp waveforms needed for PWM operation, and to synchronize all the internal circuits.
The error amplifier is designed to monitor output voltage. The amplifier compares the reference voltage with the feedback voltage divided by the
internal resistors (RFB1 and RFB2). When the FB is lower than the reference voltage, output voltage of the error amplifier increases. The gain and
frequency characteristics of the error amplifier are optimized internally.
VDD MAX circuit compares the input voltage and the output voltage then it will select the higher one as the power supply for the IC.
The IC enters chip disable state by applying low level voltage to the CE pin. At this time, the N-channel and P-channel synchronous switching
transistors are turned OFF. With XC9142C type, the load disconnection function activates even during shutdown, and because the input voltage
VBAT and output voltage VOUT are compared to optimally control the orientation of the parasitic diode of the P-channel synchronous switching
transistor, a parallel connection with other power supplies is possible.
With the XC9141 series and XC9142A/B types, the orientation of the parasitic diode of the P-channel synchronous switching transistor is fixed
at anode: VOUT and cathode: Lx during shutdown to break conduction from the input side to the output side by the parasitic diode of the P-channel
synchronous switching transistor.
When PFM operates, the N-channel driver transistor turns on at the timing of the signal sent from the PWM comparator. The N-channel driver
transistor remains on until the current in the coil reaches a constant current (IPFM).
The PWM/PFM control circuit compares the signal sent from the PWM comparator to the time it takes the current in the coil to reach a constant
current (IPFM), and outputs the pulse that results in a longer on-time of the N-channel driver transistor. This enables smooth switching between
PWM and PFM.
The XC9141 series directly outputs the signal that is sent from the PWM comparator.
12/32
XC9141/XC9142
Series
■OPERATIONAL EXPLANATION (Continued)
The maximum current limit function of XC9141A/B types and XC9142A/B/C types constantly monitors the current flowing in the N-channel driver
transistor connected to the Lx pin, and if the current in the N-channel driver transistor exceeds the current limit, the function turns off the N-channel
driver transistor. (Please refer to Fig. ILIM①)
① If the current flowing in the N-channel driver transistor exceeds the current limit value (equivalent to the peak coil current), the N-channel
driver transistor turns off, and remains off during the clock interval.
② At the next clock, the N-channel driver transistor turns on.
If overcurrent continues, ① and ② are repeated.
Note that the current in the internal N-channel driver transistor is not the same as the output current IOUT.
VOUT(T)
VBAT
VOUT
ILIM
ILx
RL
CE
①②
①②
Fig. ILIM ①
13/32
XC9141/XC9142 Series
■OPERATIONAL EXPLANATION (Continued)
The maximum current limit function of XC9141D/E and XC9142D/E/F types monitors the current that flows in the N-channel driver transistor
connected to the Lx pin, and consists of both maximum current limiting and a latch function. (Please refer to Fig.ILIM②)
Short-circuit protection is a latch-stop function that activates when the output voltage drops below the short-circuit protection threshold voltage
in the overcurrent state. (Please refer to Fig.ILIM③)
①
If the current flowing in the N-channel driver transistor exceeds the current limit value (equivalent to the peak coil current), the N-channel
driver transistor turns off, and remains off during the clock interval. In addition, an integral latch timer starts the count.
②
The N-channel driver transistor turns on at the next pulse. If in the overcurrent state at this time, the N-channel driver transistor turns off as
in (1). The integral latch timer continues the count.
③
If the count of the integral latch timer continues for 300μs typ.(@fosc=1.2MHz), a function that latches the N-channel driver transistor and Pchannel synchronous switching transistor to the off state activates.
④
If no longer in the overcurrent state at the next pulse, normal operation resumes. The integral latch timer stops the count.
Limit=300μs typ.
(@fosc=1.2MHz)
Limit