SANKEN SI

1-1-2 Switching Mode Regulator ICs
SI-8511NVS Surface-Mount, Synchronous Rectifier Step-down Switching Mode Regulator Control ICs
■Features
■Absolute Maximum Ratings
• Surface-mount package (TSSOP24)
• High efficiency due to synchronous rectification: 92% (at VIN = 5V, IO = 1A, VO = 2.5V)
• Capable of downsize a choke-coil due to IC's
high switching frequency (400kHz typ, On
Time Control). (Compared with conventional
Sanken devices)
Parameter
(Ta=25°C)
Symbol
Ratings
Unit
Control-System DC Input Voltage
VCC
7
V
DC Input Voltage
VIN
25
V
Boost Block Input Voltage
VH
30
V
EN Terminal Input Voltage
VEN
VCC
V
VPWRGD
7
V
Junction Temperature
Tj
+150
°C
Storage Temperature
Tstg
–40 to +150
°C
PWRGD Terminal Applied Voltage
• Low reference voltage (Vref) of 1.1V. The
output voltage is variable from 1.1V to 6V.
• High-speed response to a load
• Compatible with low ESR capacitors
• Soft start and output ON/OFF available
• Built-in overcurrent and output-overvoltage
protection circuits
• PWRGD function to indicate the output voltage
status
• High precision reference voltage: 1.1V ± 1.2%
■Applications
• Power supplies for notebook PCs and mobile devices
• Onboard local power supplies
• OA equipment
• For stabilization of the secondary-side output voltage of switching power supplies
■Recommended Operating Conditions
Symbol
Ratings
Unit
Control System Input Voltage Range
Parameter
VCC
4.5 to 5.5
V
Input Voltage Range
VIN
3 to 18
V
Output Voltage Range
VO
1.1 to 6
V
Operating Temperature Range
Top
–20 to +85
°C
■Electrical Characteristics
(Ta=25°C unless otherwise specified)
Parameter
Symbol
Dynamic
Output Voltage
Characteristics Temperature Coefficient of Output Voltage
∆VO/∆T
Circuit
Current
min.
–1.2%
typ.
max.
1.1
+1.2%
±0.03
Unit
V
mV/°C
Conditions
VIN=5V, VCC=5V, VSNS connected to VO, IO=0A
VIN=5V, VCC=5V, VSNS connected to VO, IO=0A, Ta=0 to 85°C
Circuit Current (VCC Terminal)
Iop
6
mA
VCC=5V, EN=H, FADJ:open
Circuit Current (VIN Terminal)
Iop
1
mA
VIN=5V, EN=H
Standby Current 1 (VCC Terminal)
Istd1
100
µA
VCC=5V, EN=L
Standby Current 2 (VIN Terminal)
Istd2
50
µA
VIN=5V, EN=L
Undervoltage UVLO Operating Voltage 1 (VCC Terminal)
Lockout
UVLO Operating Voltage 2 (VIN Terminal)
On Time
Control
VO
Ratings
Vuvlo1
3.7
4.45
V
VIN=5V
Vuvlo2
2.5
2.9
V
VCC=5V
On Time
Ton
1.27
µS
VCC=5V, VIN=5V, VO=2.5V
Minimum Off Time
Toff
0.7
µS
VCC=5V
REF Terminal Voltage
Vref
1.3
V
VCC=5V
REF Terminal Source Current
Iref
100
µA
VCC=5V
1.1
1.2
High Side
Drive
On Resistance (high side)
RonHH
5.5
Ω
VH-VLIN=5V
On Resistance (low side)
RonHL
5.5
Ω
VH-VLIN=5V
Low Side
Drive
On Resistance (high side)
RonLH
5.5
Ω
VCC=5V
On Resistance (low side)
RonLL
5.5
Ω
VCC=5V
Bootstrap
Bootstrap Voltage
Protection
System
82
VH-VLIN
4.5
Current for Current Limit Detection
Ilim
90
Soft Start Terminal Current
Iss
5
5.5
V
100
110
µA
VCC=5V, VIN=5V
µA
VCC=5V
±20
EN Low Level Voltage
Vcelo
0
0.8
V
VCC=5V
EN High Level Voltage
Vcehi
2.4
VCC
V
VCC=5V
EN Bias Level Current
ICE
5
µA
VCC=5V, EN=5V
PWRGD Good Voltage (high side)
Vsens
1.32
V
VCC=5V
PWRGD Good Voltage (low side)
Vsens
0.88
V
VCC=5V
PWRGD Low Output Voltage
Vpwrgd
0.4
V
VCC=5V, Ipwrgd=120µA
PWRGD Terminal Current
Ipwrgd
120
µA
VCC=5V, Vpwrgd=0.4V
PWRGD Leakage Current
Ipwrgd
5
µA
Vpwrgd=5V
ICs
SI-8511NVS
■External Dimensions (TSSOP24)
(Unit : mm)
2.0 φ Mirror surface
Depth 0.02 to 0.08
11
°
A
11
°
13
24
1.0 φ Mirror surface
(6.4)
12
11
°
1
11
°
1.90
3.00
7.6±0.2
5.60±0.1
Depth 0.02 to 0.08
+0.1
0.15 –0.05
0.65
0.375 TYP
0.22+0.1
–0.05
0.12 M
A
7.80±0.1
0.4
7.9±0.2
11°
1.15±0.05
11°
Plastic Mold Package Type
Flammability: UL94V-0
Product Mass: Approx. 1.36g
°
11
0.08 S
0~10
11°
0.10±0.05
S
0.50±0.2
°
■Block Diagram (Pin Assignment)
VIN
+
+5V
VCC1
ILIM
VIN ISEN
VCC2
OCP
PRE_REG
EN
H : ON
L : OFF
EN
UVLO
Vpreg
VH
Level
Shift
Gate Driver
OFF Clamp
Latch
Buff
DRVH
VO
Synchronous
Cont.
(Logic)
POWER_GOOD
H : GOOD
L : NG
PWRGD
LIN
+
Buff
Logic
Power
Good
DRVL
PGND
–
Switching
+
Constant On
Time Cont.
+
COMP
–
VO
VSNS
–
OSC
+
SS
GND
OVP_SL
FADJ
Open : Change Frequency
Short : 400KHz Operation
FSET
14
SS
12
SKIP
Open : Skip Mode
L
: No Skip Mode
■Typical Connection Diagram
VIN
R2
C1 : 10 µ F
VCC : 5V
D2 : SFPL52
C7 : 0.1 µ F
R1
5mΩ
R5
10Ω
1
2
3
4
C6
0.1 ~ 1 µ F
C9
1000
pF
5
6
7
8
VCC
R7
47kΩ
R10
2.2kΩ
R9
9
10
NC
NC
DRVH
LIN
VH
DRVL
VIN
PGND
ISEN
VCC2
ILIN
OVP_SL
SI-8511NVS
GND
VSNS
VO
VCC1
SS
EN
PWRGD
SKIP
REF
FADJ
Q1
24
L1 : 10 µ H
23
22
21
20
VO
+
Q2
D1
SJPJ-L3
R6
10Ω
C5 : 4.7 µ F
19
R12
18
C4 : 3.3 µ F
VCC
17 C8 : 220pF
16
15
EN
SKIP
PWRGD
11
12
NC
NC
14
13
R11 : 100kΩ
R8 : 200kΩ
R13
R4
47kΩ
C3
0.1 µ F
C2 :
330 µ F
MOS FET Q1, Q2
• Be sure to use logic type MOS FET as Q1 and Q2.
If you use a normal power MOS FET type, the ON resistance may not drop to a
satisfactory level due to a shortage of VGS. This may deteriorate the efficiency
and cause overheating.
Diode D1
• Be sure to use a Schottky-barrier diode for D1.
If other diodes like fast recovery diodes are used, IC may be destroyed because
of the reverse voltage generated by the recovery voltage or ON voltage.
Choke coil L1
• If the winding resistance of the choke coil is too high, the efficiency may drop
below the rated value.
• Take care concerning heat radiation from the choke coil caused by magnetic
saturation due to overload or short-circuit load.
Capacitor C1, C2
• As large ripple currents flow through C1 and C2, use high-frequency and lowimpedance capacitors suitable for switching mode power supplies. Especially
when the impedance of C2 is high, the switching waveform may become abnormal at low temperatures. For C2, do not use a capacitor with an extremely low
equivalent series resistance (ESR) such as a ceramic capacitor, which may cause
an abnormal oscillation.
* To create the optimum operating conditions, place the components as close as
possible to each other.
ICs
83