TS2581

TS2581
PWM Controller
SOP-8
Pin Definition:
1. EN/CT
8. FB
2. GND
7. OVP
3. VGATE
6. VSENSE
4. VCC
5. GATE
General Description
The TS2581 integrates Pulse-Width-Modulation (PWM) control circuit into a single chip, mainly designs for powersupply regulator. All the functions include an error amplifier, a soft-start, UVLO, OVP, SCP, TSD circuitry.
This device features an internal 100KHz oscillator, the UVLO makes sure that the outputs are off until the internal
circuit operates normally.
Features
Ordering Information
●
Input voltage：8V to 40V
●
Duty ratio：0% to 100% PWM control
●
Oscillation frequency：100K/300KHz
●
Thermal Shutdown function.
●
Short Circuit Protect (SCP).
Application
●
External SW P-channel MOS.
●
Simple High-efficiency Step down Regulator
●
External OVP setting function.
●
●
Current mode non-synchronous PWM converter
Charger
●
●
External current limit setting.
Telecommunication
●
Under voltage Lockout.
Part No.
Package
Packing
TS2581CS RLG
SOP-8
2.5kpcs / 13” Reel
Note: “G” denotes for Halogen Free
Absolute Maximum Rating
Parameter
VIN Pin Voltage
Symbol
Limit
Unit
VIN
GND - 0.3 to GND + 45
V
GND - 0.3 to VIN
V
VGATE,ISENSE Pin Voltage
Feedback, OVP, EN/CT Pin Voltage
GND - 0.3 to 6
V
Switch Pin Voltage
VSW
GND - 0.3 to VIN + 0.3
V
Power Dissipation
PD
(TJ – TA)/ θJA
W
Storage Temperature Range
TST
-40 to +165
°C
Operating Temperature Range
TOP
-20 to +125
°C
Operating Supply Voltage
VOP
+8.5 to +40
V
Symbol
Maximum
15
Thermal Information
Parameter
ӨJC
Thermal Resistance (Junction to Case)
Unit
o
C/W
o
Thermal Resistance (Junction to Ambient)
ӨJA
40
C/W
Note1: ӨJA is measured on the PCB with minimum copper area.
2
Note2: ӨJA is measured with the PCB copper area (need connect to GROUND pins) of approximately 0.5 in
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Version: A11
TS2581
PWM Controller
Electrical Specifications (Ta = 25oC unless otherwise noted, VIN=12V)
Characteristics
Symbol
Conditions
Feedback Voltage
VFB
IOUT=10mA
Under Voltage Lockout
UVLO
Falling
UVLO Hysteresis
-
OVP detect voltage
VOVP
Internal define
Min. Typ. Max. Units
0.98
1
1.02
V
-
6
-
V
-
0.8
-
V
1.07
1.1
1.13
V
Line Regulation
REGLINE
VIN=10 ~ 40V, IOUT=10mA
-
0.5
1
%
Load Regulation
REGLOAD
IOUT=0~3A, RSENSE = 33mΩ
-
30
50
mV
Quiescent Current
ICCQ
VFB = 1.5V, force driver off.
-
3
6
mA
Oscillator frequency
FOSC
IOUT = 0.5A
70
100
130
KHz
Force driver on VFB = 0.6V
-
100
-
%
Force driver off VFB = 1.5V
-
0
-
%
-
110
-
mV
-
-
0.4
V
0.5
-
1.5
V
Max. Duty Cycle (ON)
DC
Min. Duty Cycle (OFF)
Sense Voltage
VCC-VSENSE
EN/CT pin logic input threshold
voltage
VEN1
Shutdown mode
VCT
Auto restart, VFB<0.4V
Thermal shutdown Temp
TSD
-
160
-
°C
Thermal
Shutdown Hysteresis
TSH
-
45
-
°C
Block Diagram
EN/CT
VCC
2.5 V
REGULATOR
1.23V
REFERENCE
1.00V
START-UP and
Auto restart control
Current
limit
OSC.
FB
110 mV
_
CURRENT
SOURCE
BIAS
COMP.
+
+
AMP
_
+
CONTROL
+
DRIVER
COMP.
1.10V
0.4V
AMP
+
_
_
OVP
VSENSE
VGATE
OVP
GATE
+
AMP
_
Thermal
Shutdown
SCP
Line
Compensation
GND
Pin Function Description
Name
EN/CT
GND
VGATE
VCC
GATE
VSENSE
OVP
FB
Description
Shutdown and auto restart control pin
GND pin
Driver gate clamping pin. The pin must connect a 1uF capacitor to VIN
Operating voltage input
Switch pin. Connect external inductor and diode here
Voltage Sense input
Over voltage detect pin
Feedback pin
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Version: A11
TS2581
PWM Controller
Function Description
Feedback
Sense the regulated output voltage to complete the feedback loop, when VFB <0.4V, the SCP is happened.
VSENSE
The current limit sense pin, if VIN-VSENSE≧ 110mV, the over current is happened that it can turn-off driver cycle by
cycle.
OVP
The Over Voltage sense pin, If VOVP >1.10V, the OVP is happened that it can turn-off the driver. You can set
VOUT OVP voltage by outside resistances (R3 and R4), Please see below formula to set.
VOUT
( OVP )
= 1 . 10 × (1 +
R2
)
R5
The Over Voltage Protect, If VOVP >1.10V, the OVP is happened that it can turn-off the driver.
Under Voltage Lockout (UVLO)
To avoid error-operation of the device at low input voltages an under voltage lockout is included that disables the
device, if the input voltage falls below 6.0V
Thermal Consderation
The SOP-8L package needs a heat sink under most conditions. The heat sink connect exposed pad of TS2581 to
obtain best effect. The size of the heat sink depends on the input voltage, output voltage, output current and
ambient temperature.
Typical Application Circuit
VCC 10~36V
ICL =
RSENSE1
470uF
0.1u
1uF
8
7
6
5
L1
D1
4
3
2
1
VCC
VGATE
GATE
VSENSE
GND
EN/CT
OVP
FB
5
R1
0R
66uH / 33uH
R2
R3
C5
C4
Option
470uF
R4
4
C3
D
3
2
1
S
C2
P-MOS
33mR
U2
C1
5V/3A
U1
( VCC - Vsense ) / Rsense
6
B340A
7
Option
8
C6
12K
12K
R5
R6
3K
3K
Option
C7
0.1u
AX3304/A
TS2581
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Version: A11
TS2581
PWM Controller
Application Information
Setting the Output Voltage
Application circuit item shows the basic application circuit with adjustable output version. The external resistor sets
the output voltage according to the following formula:
VOUT = 1.0V × (1+
R3
)
R6
Table 1 Resistor select for output voltage setting
VOUT
R6
R3
5.0V
3.3V
3K
3K6
12K
8K2
Current Limit Protection
The Current limit is set by outside resistance (RSENSE), When the SENSE pin voltage larger than 110mV, the current
limit is happened that driver can be turned off until small than 90mV. The current limit set according to the following
formula:
Current Limit (A) =
110mV
RSENSE
The maximum output current table is shown as below; please refer the table to design.
RSENSE (Ω)
Current Limit (A)
Maximum Output Current (A)
25m
30m
50m
75m
4.4
3.66
2.2
1.46
4.1
3.3
1.9
1.1
Inductor Selection
For most designs, the different frequency can be reducing the inductor value; The TS2581 is suggested 22µH to
100µH for 100K to 300KHz frequencies. Please refer the below table to design.
L1 recommend value (VIN=10~30V ,VOUT=5V, IOUT=2A)
L1 Value (H)
68~100uF
Where is inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in high
ripple currents. Choose inductor ripple current approximately 20% of the maximum load current 3A, ∆IL=0.6A. The
DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to
prevent core saturation (3A+0.3A).
Input Capacitor Selection
This capacitor should be located close to the IC using short leads and the voltage rating should be approximately
1.5 times the maximum input voltage. The RMS current rating requirement for the input capacitor of a buck
regulator is approximately 1⁄2 the DC load current. A low ESR input capacitor sized for maximum RMS current
must be used. A 220~470µF low ESR capacitor for most applications is sufficient.
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Version: A11
TS2581
PWM Controller
Application Information (Continue)
Output Capacitor Selection
The output capacitor is required to filter the output and provide regulator loop stability. The important capacitor
parameters are; the 100 KHz Equivalent Series Resistance (ESR), the RMS ripples current rating, voltage rating,
and capacitance value. For the output capacitor, the ESR value is the most important parameter. The ESR can be
calculated from the following formula.
V
RIPPLE
= ∆ I L × ESR = 0.6A x 80mΩ= 48mV
An aluminum electrolytic capacitor’s ESR value is related to the capacitance and its voltage rating. In most case,
higher voltage electrolytic capacitors have lower ESR values. Most of the time, capacitors with much higher voltage
ratings may be needed to provide the low ESR values required for low output ripple voltage. System stability is
depending on output capacitor’s ESR, Correct to choose output capacitor’s ESR is very important. It is
recommended to using a 220~470µF, the ESR values range is 40~130mΩ.
EN/CT
The pin is enable/shutdown and auto restart control functions. When system is normal operating, this pin is
enable/shutdown function. Pulling this pin below a threshold voltage of under 0.3V shuts the regulator off, and
pulling this pin from 0.5V to 1.5V turns the regulator on. However when VOUT is short (VFB<0.4V), the auto restart
function can be started that restart the regulator cycle by cycle. The cycle time is set by outside capacitor (C6).
Please refer the below waveform and formula, the t2 cycle is regulator off time and t1 cycle is current limit time. The
charge-current is 30uA and discharge-current is 1.3uA.
Iin (A)
Current Limit
Time
V EN/CT
1.5V
0.5V
Time
0
t2
t1
Thermal Consideration
The SOP-8L package needs a heat sink under most conditions. The heat sink connect exposed pad of TS2581 to
obtain best effect. The size of the heat sink depends on the input voltage, the output voltage, the load current and
the ambient temperature.
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Version: A11
TS2581
PWM Controller
SOP-8 Mechanical Drawing
Unit: Millimeters
Marking Diagram
Y = Year Code
M = Month Code for Halogen Free Product
(O=Jan, P=Feb, Q=Mar, R=Apl, S=May, T=Jun, U=Jul, V=Aug, W=Sep,
X=Oct, Y=Nov, Z=Dec)
L = Lot Code
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Version: A11
TS2581
PWM Controller
Notice
Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf,
assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, to
any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of
sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty,
relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose,
merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify TSC for any damages resulting from such improper use or sale.
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Version: A11