ENA2019 D

Ordering number : ENA2019
LV8747TA
Bi-CMOS LSI
PWM Constant-Current Control Stepping Motor
Driver and Switching Regulator Controller
http://onsemi.com
Overview
The LV8747TA is a PWM constant-current control stepping motor driver and switching regulator controller IC.
Features
• Two circuits of PWM constant-current control stepping motor driver incorporated
• Control of the stepping motor to W1-2 phase excitation possible
• Output-stage push-pull composition enabling high-speed operation
• Two circuits of switching regulator controller incorporated
• Thermal shutdown circuit incorporated
• Timer latch type short-circuit protection circuit incorporated • Motor driver control power incorporated
• Output short-circuit protection circuit incorporated
• Chopping frequency selectable
• High-precision reference voltage circuit incorporated
• Upper and lower regenerative diodes incorporated
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Symbol
Supply voltage
VM max
Driver output peak current 1
MDIO peak1
Conditions
OUT1/OUT2 tw ≤ 10ms, duty 20%
Ratings
Unit
38
V
1.75
A
A
Driver output continuous current 1
MDIO max1
OUT1/OUT2
1.5
Driver output peak current 2
MDIO peak2
OUT3/OUT4 tw ≤ 10ms, duty 20%
0.8
A
Driver output continuous current 2
MDIO max2
OUT3/OUT4
0.5
A
Regulator output current
SWIO max
OUT5/OUT6 tw ≤ 1μs
500
mA
Allowable power dissipation 1
Pd max1
Independent IC
0.4
W
Allowable power dissipation 2
Pd max2
Our recommended four-layer substrate *1, *2
Operating temperature
Storage temperature
4.85
W
Topr
-20 to +85
°C
Tstg
-55 to +150
°C
*1 Specified circuit board : 100×100×1.6mm3 : 4-layer glass epoxy printed circuit board
*2 For mounting to the backside by soldering, see the precautions.
Caution 1) Absolute maximum ratings represent the value which cannot be exceeded for any length of time.
Caution 2) Even when the device is used within the range of absolute maximum ratings, as a result of continuous usage under high temperature, high current,
high voltage, or drastic temperature change, the reliability of the IC may be degraded. Please contact us for the further details.
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating
Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.
Semiconductor Components Industries, LLC, 2013
June, 2013
41112 SY 20120131-S00006 No.A2019-1/20
LV8747TA
Allowable Operating Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
Supply voltage
VM
10 to 35
V
Logic input voltage
VIN
0 to 5
V
VREF input voltage
VREF
0 to 3
V
Regulator output voltage
VO
Regulator output current
IO
VM-5 to VM
0 to 200
Error amplifier input voltage
VOA
Timing capacity
CT
Timing resistance
RT
Triangular wave oscillation
FOSC
V
mA
0 to 3
V
100 to 15000
pF
5 to 50
kΩ
10 to 800
kHz
frequency
Electrical Characteristics at Ta = 25°C, VM = 24V, VREF = 1.5V
Parameter
Symbol
Ratings
Conditions
min
typ
Unit
max
General
VM current drain
IM
PS = “H”, no load
6
Thermal shutdown temperature
TSD
Design guarantee
180
Thermal hysteresis width
ΔTSD
Design guarantee
REG5 output voltage
Vreg5
Ireg5 = -1mA
VGH
VM = 24V
8
mA
°C
°C
40
4.5
5.0
5.5
V
28.0
28.7
29.8
V
50
100
ms
90
120
150
kHz
Motor Drivers [Charge pump block]
Boost voltage
Rise time
tONG
VG = 10μF
Oscillation frequency
Fcp
CHOP = 20kΩ
Output block (OUT1/OUT2)
RonU1
IO = -1.5A, source side
0.5
0.8
Ω
RonD2
IO = 1.5A, sink side
0.5
0.8
Ω
Output leak current
IOleak1
VO = 35V
50
μA
Diode forward voltage
VD1
ID = -1.5A
1.0
1.3
V
RonU2
IO = -500mA, source side
1.5
1.8
Ω
1.1
1.4
Ω
50
μA
1.0
1.3
V
3
8
15
μA
30
50
70
μA
Output on resistance
Output block (OUT3/OUT4)
Output on resistance
RonD2
IO = 500mA, sink side
Output leak current
IOleak2
VO = 35V
Diode forward voltage
VD2
ID = -500mA
Logic input block
Logic pin input current
IINL
VIN = 0.8V
IINH
VIN = 5V
Logic high-level input voltage
VINH
Logic low-level input voltage
VINL
2.0
V
0.8
V
Current control block
μA
VREF input current
IREF
VREF = 1.5V
-0.5
Chopping frequency
Fchop
CHOP = 20kΩ
45
62.5
75
Threshold voltage of current setting
VHH
VREF = 1.5V, I0 = H, I1 = H
0.291
0.300
0.309
V
comparator
VLH
VREF = 1.5V, I0 = L, I1 = H
0.191
0.200
0.209
V
VHL
VREF = 1.5V, I0 = H, I1 = L
0.093
0.100
0.107
V
15
20
25
μA
0.8
1.0
1.2
V
2.475
2.500
2.525
V
kHz
Output short-circuit protection circuit
Charge current
IOCP
Threshold voltage
VthOCP
VOCP = 0V
Switching regulator Controller [Reference voltage block]
REG25 output voltage
Vreg25
Ireg25 = -1mA
Input stability
VDLI
VM = 10 to 35V
10
mV
Load stability
VDLO
Ireg25 = 0 to -3mA
10
mV
VregVM5
VregVM5 = 1mA
Internal regulator block
REGVM5 output voltage
VM-6.0
VM-5.0
V
Continued on next page.
No.A2019-2/20
LV8747TA
Continued from preceding page.
Parameter
Symbol
Ratings
Conditions
min
typ
Unit
max
Triangular wave oscillator block
Oscillation frequency
FOSC
RT = 20kΩ, CT = 620pF
Frequency fluctuation
FDV
VM = 10 to 35V
Current setting pin voltage
VRT
RT = 20kΩ
VthFB
FB5, FB6
72
80
88
kHz
1
5
%
0.91
0.98
1.05
V
1.40
1.55
1.70
V
100
mV
1.6
2.5
3.4
μA
1.65
1.8
1.95
V
100
mV
Protective circuit block
Threshold voltage of comparator
Standby voltage
VstSCP
ISCP = 40μA
Source current
ISCP
VSCP = 0V
Threshold voltage
VthSCP
Latch voltage
VltSCP
ISCP = 40μA
Source current
ISOFT
VSOFT = 0V
Latch voltage
VltSOFT
ISOFT = 40μA
Soft start circuit block
1.3
1.6
1.9
μA
100
mV
Low-input malfunction preventive circuit block
Threshold voltage
VUT
8.3
8.7
9.1
V
Hysteresis voltage
VHIS
240
340
440
mV
Error amplifier block
Input offset voltage
ViO
6
mV
Input offset current
I iO
30
nA
100
nA
Input bias current
Iib
OPEN open gain
AV
Common-phase input voltage range
VCM
Common phase removal ratio
CMRR
Max output voltage
VOH
Min output voltage
VOL
Output sink current
Isi
FB = 2.5V
Output source current
Iso
FB = 2.5V
VT100
85
VM = 10 to 35V
dB
3.0
80
4.5
V
dB
5.0
V
0.2
0.5
V
300
600
1000
μA
45
75
105
μA
Duty cycle = 100%
0.95
1.01
1.07
V
0.49
0.52
0.55
V
1
μA
PWM comparator block
Input threshold voltage
(Fosc = 10kHz)
VT0
Duty cycle = 0%
Input bias current
IBDT
DT6 = 0.4V
MAX duty cycle 1
Don1
5ch
Internally fixed
94
%
Don2
5ch
Internally fixed
92
%
Don3
6ch
VREG25 divided by 17kΩ and 8kΩ
56
(Fosc = 80kHz)
MAX duty cycle 2
(Fosc = 160kHz)
MAX duty cycle 3
(Fosc = 10kHz)
65
74
%
10
12
Ω
6
8
Ω
5
μA
Output block
Output ON resistance
Leak current
RonU3
IO = -200mA, source side
RonD3
IO = 200mA, sink side
ILEAK
VO = 35V
No.A2019-3/20
LV8747TA
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
I14
I04
PS
VREF34
OCP
OCPM
OUT5
OUT6
REGVM5
GND
NON5
INV5
FB5
NON6
INV6
FB6
Pin Assignment
1 GND
DT6 48
2 PHA4
RT 47
3 OUT4B
CT 46
4 RNF4
REG25 45
5 OUT4A
REG5 44
6 VM34
SCP 43
LV8747TA
7 OUT3B
8 RNF3
9 OUT3A
SOFT 42
VMSW 41
VREF12 40
10 PGND3
CHOP 39
11 I03
CP1 38
Top View
12 I13
CP2 37
OUT2A
VM12
VM12
OUT1B
OUT1B
RNF1
RNF1
OUT1A
OUT1A
PGND1
16 PHA2
OUT2A
I11 34
RNF2
15 I12
RNF2
I01 35
OUT2B
14 I02
OUT2B
VG 36
PGND2
13 PHA3
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
PHA1 33
Package Dimensions
unit : mm (typ)
3422
TOP VIEW
SIDE VIEW
BOTTOM VIEW
9.0
Exposed Die-Pad
0.5
7.0
(4.0)
9.0
7.0
(4.0)
64
1 2
0.4
0.18
0.125
0.1
1.2 MAX
(1.0)
(0.5)
SIDE VIEW
SANYO : TQFP64L(7X7)
No.A2019-4/20
LV8747TA
Pd max – Ta
Allowable power dissipation, Pd max – W
6.0
4.85
*1 With Exposed Die-Pad substrate
*2 Without Exposed Die-Pad
Four-layer substrate *1
4.0
Four-layer substrate *2
2.52
2.40
2.0
1.25
0
– 20
0
20
40
60
80
100
Ambient temperature, Ta – °C
Substrate Specifications (Substrate recommended for operation of LV8747TA)
Size
: 100mm × 100mm × 1.6mm (four-layer substrate [2S2P])
Material
: Glass epoxy
Copper wiring density : L1 = 85% / L4 = 90%
L1 : Copper wiring pattern diagram
L4 : Copper wiring pattern diagram
Cautions
1) The data for the case with the Exposed Die-Pad substrate mounted shows the values when 80% or more of the
Exposed Die-Pad is wet.
2) For the set design, employ the derating design with sufficient margin.
Stresses to be derated include the voltage, current, junction temperature, power loss, and mechanical stresses such as
vibration, impact, and tension.
Accordingly, the design must ensure these stresses to be as low or small as possible.
The guideline for ordinary derating is shown below :
(1)Maximum value 80% or less for the voltage rating
(2)Maximum value 80% or less for the current rating
(3)Maximum value 80% or less for the temperature rating
3) After the set design, be sure to verify the design with the actual product.
Confirm the solder joint state and verify also the reliability of solder joint for the Exposed Die-Pad, etc.
Any void or deterioration, if observed in the solder joint of these parts, causes deteriorated thermal conduction,
possibly resulting in thermal destruction of IC.
No.A2019-5/20
GND
GND
VREF12
PGND3
PGND2
PGND1
CHOP
Oscillation
circuit
LVS
TSD
+
-
5V
Charge
pump
VG
Output preamplifier stage
I10 I11
Current
selection
DAC
OUT1B VM12
PHA1
+
Output control
logic
RNF1 OUT1A
Output preamplifier stage
PS
PHA2 I02 I12
+
Output preamplifier stage
Current
selection
DAC
OUT2B
Output control
logic
OUT2A
RNF2
VREF34
+
-
RNF3
Output preamplifier stage
I03 I13
Current
selection
DAC
OUT3B
PHA3
+
Output control
logic
OUT3A
Output preamplifier stage
OCP
OUT4B
OCPM
+
RNF4
Current
selection
DAC
OUT6 OUT5
REGVM5
VM-5V
Internal
reference
voltage
VM
PHA4 I04 I14
Output control
logic
OUT4A
Over-current
protection
circuit
VM34
Output preamplifier stage
Output preamplifier stage
CP1 CP2
VMSW
CT
DT6
Triangular
wave
oscillator
RT
Short-circuit
protection
circuit
+
-
+
-
Internal ;
reference
voltage
+
+
+
+
-
+
+
-
Constant current
2.5V
reference
voltage
REG25
VMSW
SCP
SOFT
FB6
INV6
NON6
NON5
INV5
FB5
5V REG5
+
-
LV8747TA
Block Diagram
No.A2019-6/20
Output preamplifier stage
LV8747TA
Pin Functions
Pin No
Pin
Description
VM12
Driver 1/2ch Pin to connect to power supply
OUT1A
Driver 1ch OUTA output pin
OUT1B
Driver 1ch OUTB output pin
RNF1
Driver 1ch Current sense resistor connection pin
OUT2A
Driver 2ch OUTA output pin
OUT2B
Driver 2ch OUTB output pin
RNF2
Driver 2ch Current sense resistor connection pin
35
I01
Driver 1ch Output current setting input pin
34
I11
33
PHA1
Driver 1ch Output phase shift input pin
14
I02
Driver 2ch Output current setting input pin
15
I12
16
PHA2
40
VREF12
Driver 1/2ch Output current setting reference voltage input pin
32
PGND1
Driver output Power GND
17
PGND2
Driver output Power GND
6
VM34
Driver 3/4ch Power connection pin
9
OUT3A
Driver 3ch OUTA output pin
7
OUT3B
Driver 3ch OUTB output pin
8
RNF3
Driver 3ch Current sense resistor connection pin
5
OUT4A
Driver 4ch OUTA output pin
3
OUT4B
Driver 4ch OUTB output pin
4
RNF4
Driver 4ch Current sense resistor connection pin
11
I03
Driver 3ch Output current setting input pin
12
I13
13
PHA3
Driver 3ch Output phase shift input pin
63
I04
Driver 4ch Output current setting input pin
64
I14
24
25
30
31
26
27
28
29
22
23
18
19
20
21
Driver 2ch Output phase shift input pin
2
PHA4
61
VREF34
Driver 4ch Output phase shift input pin
Driver 3/4ch Output current setting reference voltage input pin
10
PGND3
Driver output Power GND
60
OCP
Pin to connect to the output short-circuit state detection time setting capacitor
59
OCPM
Over-current mode changeover pin
39
CHOP
Pin to connect to the resistor to set the chopping frequency
62
PS
Driver Power save input pin
36
VG
Charge pump capacitor connection pin
38
CP1
Charge pump capacitor connection pin
37
CP2
Charge pump capacitor connection pin
41
VMSW
Power connection pin
44
REG5
Internal regulator output pin
56
REGVM5
Internal regulator output pin
45
REG25
Regulator Reference voltage output pin
46
CT
Regulator Timing capacity external pin
47
RT
Regulator Timing resistor external pin
42
SOFT
Regulator Soft start setting pin
43
SCP
Regulator Timer and latch setting pin
54
NON5
Regulator Error amplifier 5 input + pin
Continued on next page.
No.A2019-7/20
LV8747TA
Continued from preceding page.
Pin No
Pin
Description
53
INV5
Regulator Error amplifier 5 input – pin
52
FB5
Regulator Error amplifier 5 output pin
58
OUT5
Regulator Output 5
51
NON6
Regulator Error amplifier 6 input + pin
50
INV6
Regulator Error amplifier 6 input – pin
49
FB6
Regulator Error amplifier 6 output pin
57
OUT6
Regulator Output 6
48
DT6
Regulator Output 6 MAX DUTY setting pin
55
GND
GROUND
1
GND
GROUND
No.A2019-8/20
LV8747TA
Equivalent Circuits
Pin No.
Pin Name
2
PHA4
11
I03
12
I13
13
PHA3
14
I02
15
I12
16
PHA2
33
PHA1
34
I11
35
I01
59
OCPM
62
PS
63
I04
64
I14
36
VG
37
CP2
38
CP1
Equivalent Circuit
REG5
10kΩ
100kΩ
GND
VMSW
38
REG5
37
36
100Ω
GND
3
OUT4B
4
RNF4
5
OUT4A
6
VM34
7
OUT3B
8
RNF3
9
OUT3A
10
PGND3
6
REG5
5 9
3 7
500Ω
GND
10
17
PGND2
18
OUT2B
19
OUT2B
20
RNF2
21
RNF2
22
OUT2A
23
OUT2A
24
VM12
25
VM12
26
OUT1B
27
OUT1B
28
RNF1
29
RNF1
30
OUT1A
31
OUT1A
32
PGND1
4
8
24
25
REG5
22 23
30 31
18 19
26 27
500Ω
GND
17 32
20 28
21 29
Continued on next page.
No.A2019-9/20
LV8747TA
Continued from preceding page.
Pin No.
Pin Name
40
VREF12
61
VREF34
Equivalent Circuit
REG5
500Ω
GND
39
CHOP
REG5
1kΩ
GND
60
OCP
REG5
500Ω
GND
44
REG5
VMSW
74kΩ
2kΩ
26kΩ
GND
REG25
REG5
VMSW
5kΩ
6.25kΩ
45
GND
Continued on next page.
No.A2019-10/20
LV8747TA
Continued from preceding page.
Pin No.
Pin Name
49
FB6
50
INV6
51
NON6
FB5
53
INV5
54
NON5
REG5
VMSW
VMSW
2kΩ
500Ω
2kΩ
500Ω
50 53
500Ω
52
Equivalent Circuit
GND
VMSW
51
54
48
DT6
49
52
REG5
VMSW
500Ω
GND
RT
REG5
500Ω
CT
47
500Ω
46
500Ω
500Ω
500Ω
GND
VMSW
46
57
OUT6
58
OUT5
47
VMSW
REGVM5
Continued on next page.
No.A2019-11/20
LV8747TA
Continued from preceding page.
Pin No.
Pin Name
56
REGVM5
Equivalent Circuit
VMSW
150KΩ
65KΩ
GND
42
SOFT
REG5
500Ω
500Ω
GND
VMSW
43
SCP
REG5
500Ω
GND
VMSW
No.A2019-12/20
LV8747TA
Stepping Motor Driver OUT1/OUT2(OUT3/OUT4)
(1) Output control logic
Parallel input (Note)
PS
Output
PHA
OUTA
Current direction
OUTB
Low
*
Off
Off
Standby
High
Low
Low
High
OUTB→OUTA
High
High
High
Low
OUTA→OUTB
(Note) : Enter either “H” or “L” externally for the logic input pin. Never use the input pin in the OPEN state.
(2) Constant-current setting
I0 (Note)
I1 (Note)
High
High
Output current
IO = (VREF/5) /RNF
Low
High
IO = ((VREF/5) /RNF) × 2/3
High
Low
IO = ((VREF/5) /RNF) × 1/3
Low
Low
IO = 0
(Note) : Enter either “H” or “L” externally for the logic input pin. Never use the input pin in the OPEN state.
Set current calculation method
The constant-current control setting of STM driver is determined as follows from the setting of VREF voltage, and I0
and I1, and resistor (RNF) connected between RNF and GND :
Iconst [A] = ((VREF [V] /5) /RNF [Ω]) × attenuation factor
(Example) For VREF = 1.5V, I0 = I1 = “H” and RNF = 1Ω ;
Iconst = 1.5V/5/1Ω × 1 = 0.3A
(3) Setting the chopping frequency
For constant-current control, chopping operation is made with the frequency determined by the external resistor
(connected to the CHOP pin).
The chopping frequency to be set with the resistance connected to the CHOP pin (pin 39) is as shown below.
Chopping frequency
140
Chopping frequency (kHz)
120
100
80
60
40
20
0
0
10
20
30
40
50
60
70
80
CHOP resistance (kΩ)
The recommended chopping frequency ranges from 30kHz to 120kHz.
No.A2019-13/20
LV8747TA
(4) Constant-current control time chart (chopping operation)
(Sine wave increasing direction)
STEP
Set current
Set current
Coil current
Forced CHARGE
section
fchop
Current mode CHARGE
SLOW
FAST
CHARGE
SLOW
FAST
(Sine wave decreasing direction)
STEP
Set current
Coil current
Forced CHARGE
section
Set current
fchop
Current mode CHARGE
SLOW
FAST
Forced CHARGE
section
FAST
CHARGE
SLOW
In each current mode, the operation sequence is as described below :
• At rise of chopping frequency, the CHARGTE mode begins.(The section in which the CHARGE mode is forced
regardless of the magnitude of the coil current (ICOIL) and set current (IREF) exists for 1/16 of one chopping cycle.)
• The coil current (ICOIL) and set current (IREF) are compared in this forced CHARGE section.
When (ICOIL<IREF) state exists in the forced CHARGE section ;
CHARGE mode up to ICOIL ≥ IREF, then followed by changeover to the SLOW DECAY mode, and finally
by the FAST DECAY mode for the 1/16 portion of one chopping cycle.
When (ICOIL<IREF) state does not exist in the forced CHARGE section;
The FAST DECAY mode begins. The coil current is attenuated in the FAST DECAY mode till one cycle of
chopping is over.
Above operations are repeated. Normally, the SLOW (+FAST) DECAY mode continues in the sine wave increasing
direction, then entering the FAST DECAY mode till the current is attenuated to the set level and followed by the SLOW
DECAY mode.
No.A2019-14/20
LV8747TA
(5) Output current vector locus (one step is normalized to 90 degrees)
2-phase commutation position
Channel 1 phase current ratio
100.0
66.7
33.3
0.0
0.0
33.3
66.7
100.0
Channel 2 phase current ratio
(6) Typical current waveform in each excitation mode
Two-phase excitation (1/2ch, CW mode)
I01,I11
H
PHA1
H
I02,I12
PHA2
(%) 100
IOUT1
0
-100
(%) 100
IOUT2
0
-100
No.A2019-15/20
LV8747TA
1-2 phase excitation (1/2ch, CW mode)
I01
I11
PHA1
I02
I12
PHA2
(%)
100
IOUT1
0
-100
(%)
100
0
IOUT2
-100
PCA01195
W1-2 phase excitation (1/2ch, CW mode)
I01
I11
PHA1
I02
I12
PHA2
(%)
100
IOUT1
0
-100
(%)
100
IOUT2
0
-100
PCA01196
No.A2019-16/20
LV8747TA
Output short-circuit protection circuit
To protect IC from damage due to short-circuit of the output caused by lightening or ground fault, the output short-circuit
protection circuit to put the output in the standby mode is incorporated.
(1) Output short-circuit protection operation changeover function
Changeover to the output short-circuit protection of IC is made by the setting of OCPM pin.
OCPM
State
“Low”
Auto reset method
“High”
Latch method
(Auto reset method)
When the output current is below the output short-circuit protection current, the output is controlled by the input signal.
When the output current exceeds the detection current, the switching waveform as shown below appears instead.
Exceeding the
over-current
detection
current
ON
OFF
ON
OFF
ON
Output current
1V
OCP voltage
0.5 to 1μs
256μs (TYP)
When detecting the output short-circuit state, the short-circuit detection circuit is activated.
When the short-circuit detection circuit operation exceeds the timer latch time described later, the output is changed
over to the standby mode and reset to the ON mode again in 256μs (TYP). In this event, if the over-current mode still
continues, the above switching mode is repeated till the over-current mode is canceled.
(Latch method)
Similarly to the case of automatic reset method, the short-circuit detection circuit is activated when it detects the
output short-circuit state.
When the short-circuit detection circuit operation exceeds the timer latch time described later, the output is changed
over to the standby mode.
In this method, latch is released by setting PS = “L”
(2) OCP pin constant setting method (timer latch setting)
Connect C between the OCP pin and GND, and the time up to the output OFF can be set in case of output short-circuit.
The C value can be determined as follows :
Timer latch : Tocp
Tocp ≈ C × V/I [s]
V : Threshold voltage TYP 1V
I : OCP charge current TYP 20μA
(C: Recommended constant value 100pF to 200pF)
No.A2019-17/20
LV8747TA
Switching Regulator Controller
(1) Regulator block diagram
MAXDUTY setting pin
5ch internally fixed
REG5
VMSW
DT
CT
RT
VM
5V
REG25
1.0V
Internal
reference
voltage
Triangle
wave
2.5V
reference
voltage
2.5V
0.5V
5V
Triangle wave
oscillator
5V
Constant
Current
Error amplifier
5V
+
+
1.6μA
NON
PWM comparator
5V
+
FB comparator
High during
LVS
- 5V
FB
operation
1.55V +
-
+
High during
protection
circuit
operation
OUT
5V
5V
LVS
5V
Short-circuit
protection circuit
Constant
Current
REGOUT
2.5μA
VM
Internal
reference
voltage
VM-5V
SOFT INV
SCP REGVM5
Soft start setting pin
Timer/latch setting pin
(2) Timing chart
Short-circuit protection comparator
reference voltage
Oscillator triangular wave output (CT)
Max_Duty setting voltage (DT)
Error amplifier output (FB)
1.55V
1.0V
0.5V
Output (OUT)
Triangular wave conversion output
(1)
SCP pin waveform
(2)
1.8V
Short-circuit protection
comparator output
Latch output
SOFT pin waveform
VMSW supply voltage
9.1V
No.A2019-18/20
LV8747TA
(3) SOFT pin constant setting method (Soft start setting)
The switching regulator can be set to soft-start by connecting C between the SOFT pin and GND.
Determine the C value as follows :
Soft start time : Tsoft
Tsoft ≈ C × V/I [s]
V : Error amplifier input + pin voltage (NON5/NON6)
I : SOFT charge current TYP 1.6μA
(4). SCP pin constant setting method (Timer latch setting)
The time up to the output OFF in case of regulator output short-circuit can be set by connecting C between the SCP
pin and GND.
Determine the C value as follows :
Timer latch : Tscp
Tscp ≈ C × V/I [s]
V : Threshold voltage TYP 1.8V
I : SCP charge current TYP 2.5μA
(5) RT pin constant setting method (Capacitor charge/discharge current setting)
The CT pin capacitor charge/discharge current can be set for triangular wave generation by connecting R between the
RT pin and GND.
Determine the R value as follows :
Charge/discharge current : Irt
Irt ≈ V/R [A]
V : R pin voltage TYP 0.98V
(6) CT pin constant setting method (Triangular wave oscillation frequency setting)
The triangular wave oscillation can be set (together with the setting of charge/discharge current setting of RT pin) by
connecting C between the CT pin and GND.
Determine the C value as follows :
Triangular wave oscillation frequency : Fosc
Fosc ≈ 1/{2×C×V/I} [Hz]
V : Triangle wave amplitude TYP 0.5V (Fosc = 10kHz)
*Note that the amplitude increases with the frequency.
I : Capacitor charge/discharge current. See the RT pin constant
setting method of (5).
No.A2019-19/20
LV8747TA
+
Lo
gi
c
in
100pF
pu
t
+
-
1.5V
Application Circuit
FB6
INV6
FB5
NON6
INV5
GND
NON5
OUT6
2 PHA4
REGVM5
OUT5
OCP
OCPM
1 GND
VREF34
PS
I04
I14
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
DT6 48
RT 47
3 OUT4B
CT 46
4 RNF4
REG25 45
SCP 43
LV8747TA
6 VM34
7 OUT3B
8 RNF3
9 OUT3A
10 PGND3
11 I03
12 I13
Logic input
SOFT 42
VMSW 41
I01 35
Logic input
PHA1 33
PGND1
OUT1A
OUT1A
RNF1
RNF1
OUT1B
OUT1B
VM12
VM12
OUT2A
OUT2A
RNF2
I11 34
RNF2
1.5V
CP2 37
15 I12
OUT2B
-
CP1 38
VG 36
OUT2B
+
CHOP 39
14 I02
PGND2
+
VREF12 40
13 PHA3
16 PHA2
620pF
REG5 44
5 OUT4A
- +
24V
-
+
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
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