NJU7640
-
1
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Ver.2012-08-03
Step-Down switching regulator IC with Over Current Protection
■ GENERAL DESCRIPTION ■ PACKAGE OUTLINE
■ FEATURES ■ PRODUCT VARIATION
● PWM switching control
● Pulse-by-pulse over current protection
● Operating Voltage 2.2V to 8V
● Wide Oscillator Range 300kHz to 1MHz
● Maximum Duty Cycle 100%
● Quiescent Current 800µA typ.
● Soft-Start Function Internal : 16ms typ. or adjustable
● Dead Time Control
● C-MOS Technology
● Package Outline NJU7640RB1 : MSOP8 (TVSP8)*
*MEET JEDEC MO-187-DA / THIN TYPE
■ PIN CONFIGURATION
The NJU7640 is a low voltage operation high-speed switching
regulator control IC for step-down converter, with a pulse-by-pulse
over-current protection. The pulse-by-pulse over-current protection
circuit can limit the over current in switching operation.
It incorporates a totem pole output, which can drive an external
MOS-FET easily. It also has a soft-start function and dead time
control and their times are all adjustable with external parts.
The NJU7640 is available in a small and thin 8-lead MSOP
(
TVSP
)
packa
ge
.
PIN FUNCTION
1. OUT
2. V+
3. FB
4. IN-
5. SENSE
6. DTC
7. RT
8. GND
NJU7640RB1
1 8
2 7
3 6
4 5
Over Current Protection
NJU7630
NJU7640
PWM Control
Constant Current Control
NJU7650
NJU7640RB1
(MSOP8 (TVSP8))
NJU7640
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■ BLOCK DIAGRAM
Buffer
0.5V
OSC
0.2V
0.5
RT
A
UVLO
Soft Start
Vref 1V
0.8V
0.2V
OUT
GNDRT DTC
RT
SENSE
IN-
FB
V
+
OCP
ER⋅AMP
Blanking
OUT
PW M
V+
NJU7640
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Ver.2012-08-03
■ ABSOLUTE MAXIMUM RATINGS (Ta=25°C)
PARAMETER SYMBOL MAXIMUM RATINGS UNIT
Supply Voltage V+ +9 V
Output Pin Current IO ±50 mA
Power Dissipation PD MSOP8 (TVSP8) :320 mW
Operating Temperature Range TOPR -40 to +85 °C
Storage Temperature Range TSTG -40 to +125 °C
■ RECOMMENDED OPERATING CONDITIONS (Ta=25°C)
PARAMETER SYMBOL MIN. TYP. MAX. UNIT
Operating Voltage V+ 2.2 – 8 V
Oscillator Timing Resistor RT 30 47 120 kΩ
Oscillation Frequency fOSC 300 700 1,000 kHz
■ ELECTRICAL CHARACTERISTICS (V
+=3.3V, RT=47kΩ, Ta=25°C)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Under Voltage Lockout Block
ON Threshold Voltage VT_ON V
+= L → H 1.9 2.0 2.1 V
OFF Threshold Voltage VT_OFF V
+= H → L 1.8 1.9 2.0 V
Hysteresis Voltage VHYS 60 100 – mV
Soft Start Block
Soft Start Time TSS V
T_ON → Duty=80% 8 16 24 ms
Over Current Protection Block
Current Limit Sense Voltage VSENSE Voltage between
V+–SENSE pin 0.17 0.2 0.23 V
Delay Time TDELAY VSENSE+0.1V
Delay time to OUT – 160 – ns
Sense Blanking Time TBLANK – 90 – ns
Oscillator Block
RT Pin Voltage VRT -5% 0.5 +5% V
Oscillation Frequency fOSC 630 700 770 kHz
Oscillate Supply Voltage
Fluctuations fDV V
+=2.2V to 8V – 1 – %
Oscillate Temperature
Fluctuations fDT Ta=-40 °C to +85°C – 3 – %
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■ ELECTRICAL CHARACTERISTICS (V
+=3.3V, RT=47kΩ, Ta=25°C)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
Error Amplifier Block
Reference Voltage VB -1.0% 1.00 +1.0% V
Input Bias Current IB -0.1 – 0.1
µA
Open Loop Gain AV – 80 – dB
Gain Bandwidth Product GB – 1 – MHz
IOM+_1 V
FB=1V, VIN-=0.9V 25 55 95 mA
Output Source Current IOM+_2 V
FB=1V, VIN-=0.9V, V+=2.2V 4 9 16 mA
Output Sink Current IOM- V
FB=1V, VIN-=1.1V 0.10 0.16 0.22 mA
PWM Comparate Block
VT_0 Duty=0% 0.16 0.22 0.28 V
Input Threshold Voltage VT_50 Duty=50% 0.44 0.5 0.56 V
MAXDUTY_1 V
FB=0.9V 100 – – %
Maximum Duty Cycle MAXDUTY_2 V
FB=0.9V, RDTC=47kΩ 40 50 60 %
Output Block
Output High Level
ON Resistance ROH I
O=-20mA – 10 20 Ω
Output Low Level
ON Resistance ROL I
O=+20mA – 5 10 Ω
General Characteristics
Quiescent Current IDD R
L=Non Load – 800 1200 µA
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■ TYPICAL APPLICATIONS
Step-Down Converter
SENSE
VIN VOUT
1
FET
SBD
2
3
4 5
6
7
8
RDTC
CS
IN-
FB
V
+
DTC
RT
GNDOUT
RT
COUT
CIN R2
R1
CNF
RNF
C
L
NJU7640
RSC
NJU7640
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-Ver.2012-08-03
■ TYPICAL CHARACTERISTICS
100
1000
10 100
Oscillation Frequency fOSC (kHz)
Oscillation Frequency vs. Timing Resistance
(V+=3.3V, Ta=25
oC)
Timing Resistance R
T (kΩ)
660
680
700
720
740
0246810
Oscillation Frequency fosc (kHz)
Operating Voltage V
+ (V)
Oscillation Frequency vs. Operating Voltage
(RT=47kΩ, Ta=25oC)
0
20
40
60
80
100
0 20406080100
Duty Cycle MAXDUTY (%)
Dead Time Control Resistance R
DTC (kΩ)
Duty Cycle vs. R
DTC
(V+=3.3V, RT=47kΩ, Ta=25oC)
0
25
50
75
100
0 0.2 0.4 0.6 0.8 1
Duty Cycle DUTY (%)
Current Limit Sense Voltage V
SENSE (V)
Duty Cycle vs. Current Limit Sense Voltage
(V+=3.3V, RT=47kΩ, Ta=25oC)
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■ TYPICAL CHARACTERISTICS
0.996
0.998
1
1.002
1.004
0246810
Reference Voltage VB (V)
Operating Voltage V
+ (V)
Reference Voltage vs. Operating Voltage
(V+=3.3V, Ta=25oC)
0.17
0.18
0.19
0.2
0.21
0.22
0.23
0246810
Current Limit Sense Voltage VSENSE (V)
Operating Voltage V
+ (V)
Current Limit Sense Voltage vs. Operating Voltage
(V
+=3.3V, Ta=25
oC)
0
200
400
600
800
1000
1200
1400
0246810
Quiescent Current IDD (µA)
Operating Voltage V
+ (V)
Quiescent Current vs. Operating Voltage
(RT=47kΩ, RL=Non Load, Ta=25
oC) (V+=3.3V, Gain=40dB, Ta=25
oC)
0
15
30
45
60
0
45
90
135
180
0.1 1 10 100 1000 10000
Error Amplifier Block
Voltage Gain, Phase vs. Frequency
Phase Φ (deg)
Frequency f (kHz)
Voltage Gain Av (dB)
Phase
Gain
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■ TYPICAL CHARACTERISTICS
0
2
4
6
8
10
12
14
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Output High Level ON Resistance
ROH (Ω)
Output Block
Output High Level ON Resistance
vs. Temperature (Io=-20mA)
V+=3.3V
V+=1.95V
V+=8V
0
2
4
6
8
10
12
14
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Output Low Level ON Resistance
ROL (Ω)
Output Block
Output Low Level ON Resistance
vs. Temperature (Io=+20mA)
V+=3.3V
V+=1.95V
V+=8V
1
10
100
1000
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Output Source Current I
OM+ (mA)
Error Amplifier Block
Output Source Current vs. Temperature
(VFB=1V, VIN-=0.9V)
V+=3.3V
V+=1.95V
V+=8V
0
0.05
0.1
0.15
0.2
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Output Sink Current IOM- (mA)
Error Amplifier Block
Output Sink Current vs. Temperature
(VFB=1V, VIN- =1.1V)
V+=1.95V, 3.3V, 8V
0
50
100
150
200
250
-50 -25 0 25 50 75 100 125
Ambient Temperature Ta (
oC)
Delay Time TDELAY (ns)
Delay Time vs. Temperature
(VSENSE +0.1V Delay time to OUT)
V+=3.3V
V+=1.95V
V+=8V
8
10
12
14
16
18
20
22
24
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Soft Start Time Tss (ms)
Soft Start Time vs. Temperature
(V+=3.3V)
NJU7640
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■ TYPICAL CHARACTERISTICS
0.99
0.995
1
1.005
1.01
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Reference Voltage VB (V)
Reference Voltage vs. Temperature
(V+=3.3V)
0.19
0.195
0.2
0.205
0.21
-50 -25 0 25 50 75 100 125
Ambient Temperature Ta (
oC)
Current Limit Sense Voltage VSENSE (V)
Current Limit Sense Voltage vs. Temperature
(V+=3.3V)
640
660
680
700
720
740
760
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Oscillator Frequency fOSC (kHz)
Oscillator Frequency vs. Temperature
(V+=3.3V, RT=47kΩ)
1.86
1.9
1.94
1.98
2.02
2.06
-50 -25 0 25 50 75 100 125
Ambient Temperature
Ta (oC)
Threshold Voltage (V)
Under Voltage Lockout Block
vs. Temperature
VT_OFF
VT_ON
0
200
400
600
800
1000
-50 -25 0 25 50 75 100 125
Ambient Temperature Ta (
oC)
Quiescent Current IDD (µA)
Quiescent Current vs. Temperature
(V+=3.3V, RT=47kΩ)
NJU7640
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MEMO
[CAUTION]
The specifications on this databook are only
given for information , without any guarantee
as regards either mistakes or omissions. The
application circuits in this databook are
described only to show representative usages
of the product and not intended for the
guarantee or permission of any right including
the industrial rights.
