AN8015SH Single-channel step-down, step-up, or inverting use DC-DC converter control IC Voltage Regulators

AN8015SH Single-channel step-down, step-up, or inverting use DC-DC converter control IC Voltage Regulators
Voltage Regulators
AN8015SH
Single-channel step-down, step-up, or inverting use
DC-DC converter control IC
Unit: mm
10
5
6
0.2±0.1
1
+0.1
0.15–0.05
0.5±0.2
4.3±0.30
6.3±0.30
0.625±0.10
1.5±0.2
0.1±0.1
0.625±0.10
0.5
The AN8015SH is a single-channel DC-DC converter control IC using the PWM method.
This IC can provide any one output type from among
step-down, step-up and inverting output.
Its operating supply voltage range is wide and its
consumption current is small. In addition, since it uses
the 10-pin surface mounting type package with 0.5 mm
pitch, it is suitable for highly efficient miniature potable
power supply, especially for a negative output power supply.
3.0±0.30
■ Overview
■ Features
• Wide operating supply voltage range (3.6 V to 34 V)
SSOP010-P-0225
• Small consumption current (1.8 mA typical)
• Converter control in a wide output frequency range is
Note) The package of this product will be changed
possible (2 kHz to 500 kHz).
to lead-free type (SSOP010-P-0225A). See the
• Built-in timer latch short-circuit protection circuit
new package dimensions section later of this
(charge current 1.1 µA typical)
datasheet.
• Incorporating the under-voltage lock-out (U.V.L.O.) circuit
• Incorporating a high precision reference voltage circuit
(2.46 V (allowance: ± 3%))
• Output block is open-collector (darlington) type.
• High absolute maximum rating of output current (100 mA)
• Maximum duty ratio is fixed and has small sample-to-sample variations (90% ± 5%).
■ Applications
IN+
IN−
FB
Error amp.
I
5
Out
1.11 V
VREF
S.C.P. comp.
9
10
2
0.5 V
Triangular
wave OSC
1.2 V
PWM
comparator
0.37 V
Reference
supply 2.46 V
(allowance : ± 3%)
8
RT
CT
VREF
1
6
■ Block Diagram
7
VCC
• LCD displays, digital still cameras, and PDAs
S R
Latch
1.83 V
R
O
U.V.L.O.
4
GND
S.C.P.
3
Clamp
Publication date: April 2003
SDH00005CEB
1
AN8015SH
■ Pin Descriptions
Pin No.
Symbol
Description
1
CT
Pin for connecting oscillator timing capacitor
2
RT
Pin for connecting oscillator timing resistor
3
S.C.P.
Pin for connecting the time constant setting capacitor for short-circuit protection
4
GND
Grounding pin
5
Out
Open collector type output pin
6
VCC
Power supply voltage application pin
7
VREF
Reference voltage output pin
8
IN+
Error amplifier noninverted input pin
9
IN−
Error amplifier inverted input pin
10
FB
Output pin of error amplifier
■ Absolute Maximum Ratings
Parameter
Symbol
Rating
Unit
Supply voltage
VCC
35
V
IN− terminal allowable application voltage
VIN−
− 0.3 to VREF
V
IN+ terminal allowable application voltage
VIN+
− 0.3 to VREF
V
Output terminal allowable application voltage
VOUT
35
V
Collector output current
IOUT
100
mA
PD
154
mW
Topr
−30 to +85
°C
Tstg
−55 to +150
°C
Power dissipation
*
Operating ambient temperature
Storage temperature
*
*
Note) *: Expect for the power dissipation, operating ambient temperature and storage temperature, all ratings are for Ta = 25°C.
■ Recommended Operating Range
Parameter
Symbol
Range
Unit
VIN
− 0.1 to 0.8
V
Collector output voltage
VOUT
34 (maximum)
V
Collector output current
IOUT
50 (maximum)
mA
Timing capacitance
CT
100 to 27 000
pF
Timing resistance
RT
5.6 to 15
kΩ
Oscillation frequency
fOUT
2 to 500
kHz
Reference voltage output current
IRE
−3 to 0
mA
CSCP
1 000 (minimum)
pF
Error amplifier input voltage
Soft start short-circuit protection time
constant setting capacitance
2
SDH00005CEB
AN8015SH
■ Electrical Characteristics at VCC = 12 V, RT = 15 Ω, CT = 200 pF, Ta = 25°C
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
2.386
2.46
2.534
V
Reference voltage block
Reference voltage
VREF
IREF = −1 mA
Input regulation with input fluctuation
Line
VCC = 3.6 V to 34 V, IREF = −1 mA

5
20
mV
Input regulation with input fluctuation 2
Line2
VCC = 3.6 V to 20 V


10
mV
Load regulation
Load
IREF = − 0.1 mA to −1 mA

2
10
mV
Output voltage temperature
characteristics 1
VTC1
Ta = −30°C to +25°C

± 0.5

%
Output voltage temperature
characteristics 2
VTC2
Ta = 25°C to 85°C

± 0.5

%
IRS

−20

mA
Circuit operation start voltage
VUON
2.8
3.1
3.4
V
Hysteresis width
VHYS
100
200
300
mV
VIO
−6

6
mV
IB
−500
−25

nA
Common-mode input voltage range
VICR
− 0.1

0.8
V
High-level output voltage
VEH

V
Low-level output voltage
VEL
Output sink current
ISINK
Reference short-circuit current
U.V.L.O. block
Error amplifier block
Input offset voltage
Input bias current
Output source current
Open-loop gain
Common-mode ripple rejection ratio
VREF − 0.3 VREF − 0.1

0.1
0.3
V
VFB = 0.8 V

8

mA
ISOURCE VFB = 0.8 V

−120

µA
AV

70

dB
CMRR

50

dB
Output block
Oscillation frequency
fOUT
RT = 15 kΩ, CT = 200 pF
175
195
215
kHz
Maximum duty ratio
Dumax
RT = 15 kΩ, CT = 200 pF
85
90
95
%
Output saturation voltage
VOL
IO = 50 mA, RT = 15 kΩ

0.9
1.2
V
Output leak current
ILEAK
VCC = 34 V,
when output transistor is off


10
µA
RT terminal voltage
VRT

0.5

V

500

kHz
Maximum oscillation frequency
fOUT(max) RT = 5.6 kΩ, CT = 150 pF
Frequency supply voltage
characteristics
fdV
fOUT = 200 kHz,
VCC = 3.6 V to 34 V

±2

%
Frequency temperature characteristics 1
fdT1
fOUT = 200 kHz,
Ta = −30°C to +25°C

±3

%
Frequency temperature characteristics 2
fdT2
fOUT = 200 kHz,
Ta = 25°C to 85°C

±3

%
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AN8015SH
■ Electrical Characteristics at VCC = 12 V, RT = 15 Ω, CT = 200 pF, Ta = 25°C (continued)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Short-circuit protection circuit block
Input threshold voltage
VTHPC
1.73
1.83
1.93
V
Input standby voltage
VSTBY
1.15
1.25
1.35
V
Input latch voltage
VIN

30
120
mV
Charge current
ICHG
Comparator threshold voltage
VTHL
VSCP = 0 V
−1.32
−1.1 − 0.88
µA

1.83

V
Whole device
Total consumption current
ICC
RT = 15 kΩ

1.8
2.8
mA
Total consumption current 2
ICC2
RT = 5.6 kΩ, CT = 150 pF

2.5

mA
■ Terminal Equivalent Circuits
Pin No.
1
Equivalent circuit
VREF
To PWM input
IO
OSC
comp.
1
210
2
VREF
100 Ω
Description
I/O
CT:
The terminal used for connecting a timing capacitor to set oscillation frequency.
Use a capacitance value within the range of 100 pF
to 27 000 pF.
Use a oscillation frequency in the range of 2 kHz
to 500 kHz.
O
RT:
The terminal used for connecting a timing resistor
to set oscillation frequency.
Use a resistance value within the range of 5.6 kΩ
to 15 kΩ . The terminal voltage is 0.5 V typ.
I
S.C.P.:
The terminal used for connecting a capacitor to set
the time constant of soft start and timer latch shortcircuit protection circuit.
Use a capacitance value in the range of more than
1 000 pF.
The charge current is about 1.1 mA at RT = 15 kΩ
VRT
1
ICHG =
×
[A]
RT
30
O
GND:
Grounding terminal

OSC PWM
S.C.P.
2 RT (VRT ≈ 0.5 V)
3
VREF
ICHG
CT
S.C.P.
1.83 V
3
4
PWM
Latch
S
Q
R
4
4
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AN8015SH
■ Terminal Equivalent Circuits (continued)
Pin No.
Equivalent circuit
5
VREF
5
6
VCC
Out:
Open-collector type (darlington) output terminal.
The absolute maximum rating of output current is
100 mA
Use with a steady-state output current under 50
mA.
O

VREF:
The output terminal for the reference voltage (2.46
VREF overcurrent detection V)
Use with a load current −3 mA or under.
This terminal is incorporating the short-circuit
protection circuit, and the short-circuit current is
Bias to other block
about −20 mA. Use the VREF for the reference
7
input setting of the error amplifier.
O
IN+:
The noninverted input terminal of the error amplifier.
For common-mode input, use in the range of − 0.1
V to +0.8 V.
I
IN−:
The inverted input terminal of the error amplifier.
For common-mode input, use in the range of − 0.1
V to +0.8 V.
I
FB:
The output terminal of the error amplifier.
The source current is about −120 µA, and the sink
current is about 8 mA.
Correct the frequency characteristics of the gain
and the phase by connecting a resistor and a capacitor between this terminal and IN− terminal.
O
8
VREF
9
9
10
I/O
VCC:
The terminal for applying supply voltage.
Use with a operating supply voltage within the
range of 3.6 V to 34 V.
6
7
Description
8
VREF
120 µA
CT
8 mA
10
PWM
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AN8015SH
■ Application Notes
[1] Main characteristics
Reference voltage temperature characteristics
Maximum duty ratio temperature characteristics
91.0
2.50
VCC = 12 V
CT = 200 pF
RT = 15 kΩ
Maximum duty ratio Dumax (%)
Reference voltage VREF (V)
VCC = 12 V
IREF = −1 mA
2.49
2.48
2.47
2.46
2.45
−40
−20
0
20
40
60
80
90.5
90.0
89.5
89.0
−40
100
40
60
100
80
Timing capacitance  Oscillation frequency
1M
VCC = 12 V
CT = 200 pF
RT = 15 kΩ
195
190
185
−20
0
20
40
60
80
100k
RT = 10 kΩ
RT = 15 kΩ
10k
1k
100
100
Ambient temperature Ta (°C)
90
RT = 15 kΩ
80
100k
100 000
10 000
Oscillation frequency  Triangular wave maximum
amplitude voltage
Triangular wave maximum amplitude voltage (V)
VCC = 12 V
Ta = 25°C
RT = 5.6 kΩ
70
10k
1 000
Timing capacitance CT (pF)
Maximum duty ratio  Oscillation frequency
100
VCC = 12 V
Ta = 25°C
RT = 5.6 kΩ
Oscillation frequency fOUT (Hz)
Oscillation frequency fOUT (kHz)
20
Oscillation frequency temperature characteristics
180
−40
Maximum duty ratio Dumax (%)
0
Ambient temperature Ta (°C)
200
1M
1.4
1.2
1.0
0.8
VCC = 12 V
RT = 15 kΩ
Ta = 25°C
0.6
0.4
0.2
0
10k
100k
Oscillation frequency fOUT (Hz)
Oscillation frequency fOUT (Hz)
6
−20
Ambient temperature Ta (°C)
SDH00005CEB
1M
AN8015SH
■ Application Notes (continued)
[1] Main characteristics (continued)
Supply voltage  Reference voltage
Supply voltage  Total consumption current
3.0
3.0
Ta = 25°C
IREF = −1 mA
Total consumption current ICC (mA)
Ta = 25°C
Reference voltage VREF (V)
2.5
2.0
1.5
1.0
0.5
2.5
RT = 5.6 kΩ
2.0
RT = 15 kΩ
1.5
1.0
0.5
0
0
2
1
3
0
5
4
0
5
4
Reference voltage line regulation
Total consumption current line regulation
3.0
Ta = 25°C
IREF = −1 mA
Ta = 25°C
Total consumption current ICC (mA)
Reference voltage VREF (V)
3
Supply voltage VCC (V)
2.52
2.50
2.48
2.46
2.44
2.5
RT = 5.6 kΩ
2.0
RT = 15 kΩ
2.42
0
5
10
15
20
25
30
1.5
35
0
5
10
15
20
25
30
35
Supply voltage VCC (V)
Supply voltage VCC (V)
Timing resistance  Total consumption current
Timing resistance  Output saturation voltage
0.85
2.5
VCC = 12 V
Ta = 25°C
IO = 50 mA
VCC = 12 V
Ta = 25°C
Output saturation voltage VOL (V)
Total consumption current ICC (mA)
2
1
Supply voltage VCC (V)
2.0
1.5
0.84
0.83
0.82
0.81
0.80
1.0
4
8
12
16
4
20
8
12
16
20
Timing resistance RT (kΩ)
Timing resistance RT (kΩ)
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AN8015SH
■ Application Notes (continued)
[2] Timing chart
3.1 V typ.
Lock-out release
Supply voltage (VCC)
3.6 V
VREF rise time
tr (VREF) ≥ 10 [µs]
Reference voltage (VREF)
2.46 V
Error amplifier output (FB)
Power supply
on
1.83 V
Triangular wave (CT) Dead-time voltage (VDT)
1.20 V
1.11 V
0.37 V
High
S.C.P. terminal voltage
Output transistor collector waveform
(Out)
Low
Soft start operation
Maximum duty 90%
Figure 1. PWM comparator operation waveform
Reference voltage (VREF)
2.46 V
Short-circuit protection input threshold level
Comparator threshold level
1.83 V
S.C.P. terminal voltage
Dead-time voltage (VDT)
1.20 V
1.11 V
Error amplifier output (FB)
0.37 V
Triangular
wave (CT)
0.03 V
High
Output transistor
collector waveform (Out)
Low
Short-circuit protection
comparator output
tPE
High
Low
Figure 2. Short-circuit protection operation waveform
8
SDH00005CEB
AN8015SH
■ Application Notes (continued)
[3] Function descriptions
1. Reference voltage block
This block is composed of the band gap circuit, and outputs the temperature compensated 2.46 V reference
voltage to the VREF terminal (pin 7). The reference voltage is stabilized when the supply voltage is 3.6 V or higher,
and used as the operating power supply for the IC inside. It is possible to take out a load current of up to −3 mA .
Also, an overcurrent protection circuit is built in for the load, thereby protecting the IC from destruction when
VREF terminal is short circuited.
2. Triangular wave oscillation block
The triangular wave which swings from the highest wave of approximately 1.4 V to the lowest wave of
approximately 0.37 V will be generated by connecting a timing capacitor and a resistor to the CT terminal (pin 1) and
RT terminal (pin 2) respectively. The oscillation frequency can be freely decided by the value of CT and RT
connected externally.
The triangular wave is connected with the inverted input of PWM comparator of the IC inside.
3. Error amplifier block
This block detects the output voltage of DC-DC converter by the pnp transistor input type error amplifier, and
inputs the amplified signal to the PWM comparator.
The common-mode input voltage range is − 0.1 V to 0.8 V, and is a voltage obtained by dividing the reference
voltage with resistors.
Also, it is possible to perform the gain setting and the phase compensation arbitrarily by inserting the feedback
resistor and capacitor between the error amplifier output terminal (pin 10) and the inverted input terminal (pin 9).
The output voltage VOUT, if positive, is obtained by connecting the resistor-divided reference voltage to the
noninverted input terminal as shown in figure 3. 1), and the output voltage VOUT, if negative, is obtained by
connecting to the inverted input terminal as shown in figure 3. 2). The output voltages in each of these cases are
given in the following equations.
VOUT = VIN+ ×
R1 + R2
R2
VIN+ = VREF ×
R4
R3 + R4
R3
R2
R4
VREF 7
IN+ 8
R3 + R4
+ VREF
R3
R2
R1 + R2
VREF 7
PWM comparator
Error amp. input
R1
R3
R2
R4
IN− 9
RNF
IN+ 8
PWM comparator
Error amp. input
IN− 9
RNF
VOUT
CNF
FB 10
R1
VIN− = VREF ×
FB 10
VOUT
VOUT = − (VREF − VIN−) ×
CNF
1) If output is positive
2) If output is negative
Figure 3. Connection method of error amplifier
4. Timer latch short-circuit protection circuit
This circuit protects the external main switching devices, flywheel diodes, and choke coils, etc. from
destruction or deterioration if overload or short-circuit of power supply output lasts for a certain time.
The timer latch short-circuit protection circuit detects the output level of the error amplifier. When the output
voltage of DC-DC converter drops and the output level of error amplifiers exceeds 1.85 V, the low-level output is
given and the timer circuit is actuated to start the charge of the external protection enable capacitor.
If the output of the error amplifier does not return to a normal voltage range by the time when the voltage of
this capacitor reaches 1.83 V, it sets the latch circuit, cuts off the output drive transistor, and sets the dead-time at
100%.
SDH00005CEB
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AN8015SH
■ Application Notes (continued)
[3] Function descriptions (continued)
5. Low input voltage malfunction prevention circuit (U.V.L.O.)
This circuit protects the system from destruction or deterioration due to control malfunction when the supply
voltage is low in the transient state of power on/off.
The low input voltage malfunction prevention circuit detects the internal reference voltage which changes
according to the supply voltage level. Until the supply voltage reaches 3.1 V during its rise time, it cuts off the
output drive transistor, sets the dead-time at 100% and holds the S.C.P. terminal (pin 3) to low level. During the
fall time of the power supply voltage, it has hysteresis width of 200 mV and operates 2.9 V or less.
6. PWM comparator block
The PWM comparator controls the on-period of the output pulse according to the input voltage. It turns on the
output transistor during the period when the triangular wave of CT terminal (pin 1) of noninverted input is lower
than any one of the following voltages : the voltage of the error amplifier output (pin 10) of the inverted input,
S.C.P. terminal (pin 3), and the voltage for dead-time which is fixed inside the IC.
The S.C.P. terminal voltage is kept at 1.25 V in the state in which DC-DC converter output is stabilized.
However, when the power supply is turned on, the soft start is activated, which gradually extends on-period
according to the time constant determined by the capacitance of externally attached capacitor and the charge
current. The maximum duty ratio is fixed at approximately 90% by the voltage for dead-time.
7. Output block
The output drive transistor is of open-collector type output connected in darlington circuit of emitter common
GND. The breakdown voltage of collector output terminal (pin 5) is 34 V and it is possible to obtain up to 100 mA
output current.
[4] Triangular wave oscillation circuit
1. Oscillation frequency setting method
The waveform of triangular wave oscillation is obtained by charging and discharging of the constant current
IO from the external timing capacitor CT which is connected to CT terminal (pin 1). The constant current is set by
the externally attached timing resistor RT .
The peak value of the wave VCTH and the trough
VCTH = 1.4 V typ.
value of the wave VCTL are fixed at approximately 1.4 V
typical and 0.37 V typical respectively.
The oscillation frequency fOSC is obtained by the
following formula;
VCTL = 0.37 V typ.
1
IO
t
t
1
2
fOSC =
=
t1 + t 2
2 × CT × (VCTH − VCHL)
Charging Discharging
VRT
0.5
whereas IO = 2 ×
=2×
RT
RT
T
because
VCTH − VCTL = 0.83 V
Figure 4. Triangular wave oscillation waveform
1
fOSC =
1.66 × CT × RT
The output frequency fOUT is equal to fOSC since it is PWM-controlled.
10
SDH00005CEB
AN8015SH
■ Application Notes (continued)
Oscillation frequency fOUT (Hz)
[4] Triangular wave oscillation circuit (continued)
2. Usage notes
This IC uses the constant current given by the timing resistor RT as the bias current of the triangular oscillation
block and the PWM comparator for consumption current reduction. The total consumption current is approximately 1.8 mA (typical) when RT is 15 kΩ, and it increases to approximately 2.5 mA (typical) when RT is 5.6 kΩ.
In order to obtain the steady-state output current of 100 mA at the open collector output, it is necessary to set RT
value to 15 kΩ or smaller.
It is possible to use the circuit in the recom1M
mended operating range of 2 kHz to 500 kHz of the
oscillation frequency. However, the timing resistor
500 k
RT versus the oscillation frequency should be set
Recommended operating
within the recommended range shown in figure 5.
condition
100 k
Also, refer to the "Applications Notes, [1] Main
characteristics, Timing capacitance  Oscillation
frequency" for setting the timing capacitance.
10 k
For a high frequency use, the overshoot and undershoot amounts increase due to operation delay
of the triangular oscillation comparator, and the
maximum duty ratio drops. This effect can be alle1k
viated by speeding up through the reduction of the
10 k
5 k 5.6 k
15 k
resistor RT and increase in the circuit current.
Timing resistance RT (Ω)
Note that this IC can not be used as an IC for
Figure 5. Timing resistance recommended condition
slave when the several ICs are operated in parallel
synchronous mode.
[5] Time constant setting method for short-circuit protection circuit with joint-use of soft start/timer latch type
The constructional block diagram of protection latch circuit is shown in figure 6. The comparator for short-circuit
protection compares the output of error amplifier VFB with the reference voltage of 1.85 V at all the time.
When the load conditions of DC-DC converter output is stabilized, there is no fluctuation of error amplifier
output and the short-circuit protection comparator also keeps the balance. At this moment, the output transistor Q1 is
in the conductive state and the S.C.P. terminal is hold to approximately 1.25 V through the clamp circuit.
When the load conditions suddenly change, and high-level signal (1.85 V or higher) is input from the error
amplifier to the noninverted input of the short-circuit protection comparator, the short-circuit protection comparator
outputs the low-level signal. Since this signal cuts off the output transistor Q1, the S.C.P. terminal voltage VPE is
released, and the externally connected capacitor CS starts charging according to the following equation:
tPE
VPE = VSTBY + ICHG ×
[V]
CS
1.83 V = 1.25 V + ICHG ×
CS = ICHG ×
tPE
CS
tPE
[F]
0.58
ICHG is the constant current determined by the oscillation timing resistor RT and its dispersion and fluctuation with
temperature are small. ICHO is expressed in the following equation:
ICHG =
VRT
1
×
[A]
RT
30
VRT is approximately 0.5 V and ICHO becomes approximately 1.1 µA when RT = 15 kΩ.
SDH00005CEB
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AN8015SH
■ Application Notes (continued)
[5] Time constant setting method for short-circuit protection circuit with joint-use of soft start/timer latch type
(continued)
When the external capacitor CS has been charged up to approximately 1.83 V, it sets the latch circuit, cuts off the
output drive transistor by enabling the low input voltage malfunction prevention circuit, and sets the dead-time at
100%.
The low input voltage malfunction prevention circuit is once enabled, the S.C.P. terminal voltage is discharged to
approximately 30 mV but the latch circuit is not reset unless the power is turned off.
The S.C.P. terminal voltage is inputted to the PWM comparator, and the soft start is actuated when the power turns
on. However, since at the beginning of power on, the error amplifier output is high level, and VPE of S.C.P. terminal
voltage is released and charging begins; the external capacitor should be set so that the output voltage of DC-DC
convertor starts to rise before the latching circuit is set. The charging equation is as same as the above. The soft start
time tSS until the input standby voltage VSTBY becomes 1.25 V is given in the following equations:
1.25 V = 0.03 V + ICHG ×
tSS = 1.22 ×
IN+
ICHG
VREF
ICHG
Error amp.
Clamp
circuit
1.25 V
S R
Latch
S.C.P. comp.
Q2
Q1
9
10
PWM comparator input
[s]
1.83 V
S.C.P.
3
IN−
FB
8
CS
tSS
CS
CS
Figure 6. Short-circuit protection circuit
12
SDH00005CEB
R
U.V.L.O.
Output cut-off
AN8015SH
■ Application Circuit Examples
1. Chopper method step-down type
VCC
120 kΩ
0.1 µF
1 000 pF
8.2 kΩ
4.5 kΩ
Out 5
6 VCC
7 VREF
0.1 µF
VO
5V
SBD
GND 4
8 IN+
15 kΩ
S.C.P. 3
RT 2
CT 1
10 FB
9 IN−
3.6 kΩ
200 pF
25.5 kΩ
2. Chopper method inverting type
130 kΩ
120 kΩ
6 VCC
Out 5
0.1 µF
7 VREF
8 IN+
S.C.P. 3
9 IN−
10 FB
RT 2
15 kΩ
VO
−24 V
8.2
kΩ
GND 4
9.1
kΩ
1 000 pF
CT 1
SBD
0.1 µF
3.6 kΩ
200 pF
VCC
SDH00005CEB
13
AN8015SH
■ Application Circuit Examples (continued)
3. On/off circuit example
1) Method to cut VCC line
VCC
Standby current ≈ 0 µA
Out 5
SBD
6 VCC
ICC
Out 5
7 VREF
GND 4
IN+
8
S.C.P. 3
IN−
9
RT
2
FB
VO
C8
C7
10
On/off
C8
VCC
Consumption current
when output off ≈ 1.8 mA
1
SBD
6 VCC
7 VREF
2) Method to cut S.C.P. line
CT
Q1
ICC
GND 4
IN+
8
S.C.P.
3
IN−
9
2
RT
10
CT
1
FB
C7
VO
Q2
On/off
4. Using method
Since the on/off circuit is not incorporated in this IC, it is required to add on/off circuit externally to provide a
standby function.
When the switch (Q1) is inserted between the VCC line and the Vcc pin of the IC (pin 6) as shown in 3. 1), the standby
current is suppressed to 0. When the output is turned off by decreasing the S.C.P. terminal voltage below the lower
limit of the triangular wave (0.37 V typical) as shown in 3. 2), the consumption current does not decrease because the
IC is operating.
5. Usage notes
The rise time of the VCC becomes sharp especially in the case of 3. 1). At that time, there is a case that the internal
latch circuit of the IC is set so that the circuit fails to start. Adjust C7 or C8 so that the rise time for VREF pin (pin 7)
becomes 10 ms or longer.
14
SDH00005CEB
AN8015SH
■ New Package Dimensions (Unit: mm)
• SSOP010-P-0225A (Lead-free package)
3.00±0.20
10
6
+0.10
0.15-0.05
4.30±0.20
6.30±0.30
(1.00)
0° to 10°
0.50±0.20
0.20+0.10
-0.05
Seating plane
1.50±0.20
5
0.50
0.10±0.10
1
(0.50)
SDH00005CEB
Seating plane
15
Request for your special attention and precautions in using the technical information
and semiconductors described in this material
(1) An export permit needs to be obtained from the competent authorities of the Japanese Government
if any of the products or technologies described in this material and controlled under the "Foreign
Exchange and Foreign Trade Law" is to be exported or taken out of Japan.
(2) The technical information described in this material is limited to showing representative characteristics and applied circuits examples of the products. It neither warrants non-infringement of intellectual property right or any other rights owned by our company or a third party, nor grants any license.
(3) We are not liable for the infringement of rights owned by a third party arising out of the use of the
product or technologies as described in this material.
(4) The products described in this material are intended to be used for standard applications or general
electronic equipment (such as office equipment, communications equipment, measuring instruments and household appliances).
Consult our sales staff in advance for information on the following applications:
• Special applications (such as for airplanes, aerospace, automobiles, traffic control equipment,
combustion equipment, life support systems and safety devices) in which exceptional quality and
reliability are required, or if the failure or malfunction of the products may directly jeopardize life or
harm the human body.
• Any applications other than the standard applications intended.
(5) The products and product specifications described in this material are subject to change without
notice for modification and/or improvement. At the final stage of your design, purchasing, or use of
the products, therefore, ask for the most up-to-date Product Standards in advance to make sure that
the latest specifications satisfy your requirements.
(6) When designing your equipment, comply with the guaranteed values, in particular those of maximum rating, the range of operating power supply voltage, and heat radiation characteristics. Otherwise, we will not be liable for any defect which may arise later in your equipment.
Even when the products are used within the guaranteed values, take into the consideration of
incidence of break down and failure mode, possible to occur to semiconductor products. Measures
on the systems such as redundant design, arresting the spread of fire or preventing glitch are
recommended in order to prevent physical injury, fire, social damages, for example, by using the
products.
(7) When using products for which damp-proof packing is required, observe the conditions (including
shelf life and amount of time let standing of unsealed items) agreed upon when specification sheets
are individually exchanged.
(8) This material may be not reprinted or reproduced whether wholly or partially, without the prior written
permission of Matsushita Electric Industrial Co., Ltd.
2002 JUL
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