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PDF SM8172A Data sheet ( Hoja de datos )
| Número de pieza | SM8172A | |
| Descripción | 2-output Power Supply IC | |
| Fabricantes | NPC | |
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SM8172A
2-output Power Supply IC
1. OVERVIEW
The SM8172A is a 2-output power supply IC that incorporates a step-down DC/DC converter and series regu-
lator with built-in reset circuit. The DC/DC converter is a PWM-type synchronous rectifier. The SM8172A has
soft start, overcurrent detection, supply undervoltage lockout, and thermal shutdown circuits built-in, making it
ideal as a supply voltage source IC for large-scale LSIs that operate from a 5V supply.
2. FEATURES
I Input voltage range: 4.5 to 5.5V
I Standby current: 0.01µA (typ)
I Series regulator
• Feedback-type current limiter to reduce output
current when outputs are short-circuit
• Output voltage: 3.3V
(available for optional setting from 2.1 to 3.6V
by 0.1V-step)
• Maximum output current: 450mA
• Voltage accuracy: ± 2% (VIN = 5.0V, Ta = 25°C)
I DC/DC converter
• Current-mode operation for excellent transient
response
• Output voltage: 0.8 to 1.8V
(typ, selectable by external resistor)
• Maximum output current: 900mA
• Operating frequency: 2MHz (typ)
• Voltage accuracy: ± 2%
(FB pin, VIN = 5.0V, Ta = 25°C, DCOUT = 1.0V)
I Reset circuit built-in
• Reset detection voltage: 3.7V (typ)
(available for optional setting from 3.2 to 4.2V
by 0.1V-step)
• Reset return delay time: 65ms (typ)
(50ms, 32ms, 16ms, and 8ms selectable with
option)
I Various protection circuit built-in
• Startup soft start circuit built-in
• Overtemperature thermal shutdown (TSD) circuit
built-in
• Supply undervoltage lockout (UVLO) circuit
built-in
I Package: 10-pin SON
3. APPLICATIONS
I ODD
I DVD player/recorder
I Next-generation DVD player/recorder
I Electronic equipment
4. TYPICAL APPLICATION CIRCUIT
5.0V
C1
10µF
VIN1
PGND
RESETN
R3
10kΩ
RESETN output
C2
10µF
DC/DC control
Regulator control
VIN2
GND
ENDCO
ENLDO
LDOUT
FB
LX
C5
3.3µF
Regulator output
R2
330kΩ
C3 R1
8pF 220kΩ
L
2.2µH
C4
4.7µF
DCOUT
(1.0V)
Note. RESETN is open-drain, therefore, please take care so that the High level signal does not exceed the absolute maximum rating of IC which receives
the reset signal. Besides, if the rest signal is not used, RESETN should be connected to GND.
5. ORDERING INFORMATION
Device
SM8172AD
Package
10-pin SON
SEIKO NPC CORPORATION —1
1 page  
SM8172A
11-3. DC/DC Converter
VIN1 = VIN2 = 5.0V, GND = PGND = 0V, Ta = 25°C unless otherwise noted.
Parameter
Pin Symbol
Condition
Rating
min typ max
Unit
Current consumption 1
Current consumption 2
Soft start time*1*2
Output voltage range*2
FB voltage
Maximum output current*2*3
Switching frequency
Supply-side switch ON resistance
GND-side switch ON resistance
LX leakage current
Overcurrent protection circuit
operating current
VIN1, 2
VIN1, 2
–
–
FB
–
LX
LX
LX
LX
LX
IDD1
IDD2
tSS
VDCO
VFB
IDCO
fOSC
RONP
RONN
ILEAKLX
No load, switching stopped
FB = VIN1, LX = Open
IDCO = 50mA
IDCO = –50mA
Standby mode, LX = 1/2VIN
ILIMITLX Supply-side switch
–
0.35 0.75
mA
– 2.5 5.5 mA
0.2 0.6 1.0 ms
0.8 – 1.8 V
0.588 0.6 0.612
V
900 –
– mA
1.7 2.0 2.3 MHz
– 0.3 – Ω
– 0.3 – Ω
–1.0 –
1.0 µA
– 1.5 –
A
*1. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the DC/DC converter output raise
time. If the maximum load current is output after soft start time startup, the output voltage does not fall. But, if the maximum load current is output
before soft start time startup, it should be careful that the output voltage may fall.
High
ENDCO
Low
LX switching start
Current limit
1.5A (typ)
DCOUT
Soft start time
1.8V
1.0V
42µsec (typ) 28µsec (typ)
The LX starts the switching operation after 42µs from ENDCO rising. After switching operation startup, the output current limit operates like linear
increase (load current = 0A). The DC/DC converter output voltage rise time varies with the load current, output capacitance, and other conditions.
SEIKO NPC CORPORATION —5
5 Page 
SM8172A
12-7. Standby Mode
When both ENDCO and ENLDO are LOW, the device switches to standby mode, and all the RESETN, con-
verter, and regulator outputs stop.
12-8. Timing Diagrams
12-8-1. Supply Voltage (VIN1 = VIN2 = ENDCO = ENLDO)
VRESETNH
VRESETNL
VUVLOH
VUVLOL
VIN1
VIN2
ENABLE
VRESETN
(Pull-up)
Reset return delay time
65msec (typ)
VDCOUT
VLDOUT
800µsec (typ)*1
70µsec (typ)*1
DC/DC, regulator output stop
by UVLO lockout
LDOUT (regulator output)
DCOUT (DC/DC output)
DC/DC, regulator output permission
DC/DC soft start time*2
0.6msec (typ)
LDO soft start time*2
1msec (typ)
*1. A time interval example for a typical application circuit with no load. The series regulator and DC/DC converter output voltage rise times may vary with
the load current, output capacitance, and other conditions.
*2. The soft start time is the interval during which the output current is limited internally in the IC, and is different from the series regulator and DC/DC con-
verter output raise time.
Note. When the supply voltage is below approximately 0.8V, there is insufficient drive for the IC to operate normally and the RESETN output level is unde-
fined. Normally, a pull-up resistor is connected to RESETN, which sets the RESETN output level to pull-up voltage.
SEIKO NPC CORPORATION —11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet SM8172A.PDF ] | |
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