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PDF TD1722 Data sheet ( Hoja de datos )
| Número de pieza | TD1722 | |
| Descripción | Single Buck Voltage Mode PWM Controller | |
| Fabricantes | Techcode | |
| Logotipo |  |
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Techcode®
Single Buck Voltage Mode PWM Controller
DATASHEET
TD1722
General Description
Features
The TD1722 is a voltage mode, fixed 200kHz/300kHz/600kHz Wide 5V to 12V Supply Voltage
switching frequency, synchronous buck converter. The APW Power-On-Reset Monitoring on VCC
8722 allows wide input voltage that is either a single 5~1 Excellent Output Voltage Regulations
2V or two supply voltage(s) for various applications. A 0.6V Internal Reference for TD1722/A/D
power-on-reset (POR) circuit monitors the VCC supply voltage 0.8V Internal Reference for TD1722B/C
to prevent wrong logic controls.
±0.6% Over-Temperature Range
A built- in soft-start circuit prevents the output voltages from Integrated Soft-Start
over- shoot as well as limits the input current. An internal
Voltage Mode PWM Operation with External
0.6V/0.8V Temperature-compensated reference voltage
Compensation
with high accuracy is designed to meet the requirement of Up to 90%DutyRatio for Fast Transient Response
low out- put voltage applications. The APW8722 provides Constant Switching Frequency
excel- lent output voltage regulations against load
300kHz ±10% for TD1722/B
current variation. The controller’s over-current protection 200kHz ±10% for TD1722C
monitors the out- put current by using the voltage drop 600kHz ±10% for TD1722A/D
across the RDS (ON) of low-side MOSFET, eliminating the
Integrated Bootstrap Forward P-CH MOSFET
need for a cur- rent sensing resistor that features high
50%Under-Voltage Protection
efficiency and low cost. In addition, the TD1722 also
125%Over-Voltage Protection
integrates excel- lent protection functions. The over-voltage Adjustable Over-Current Protection Threshold
protection (OVP), under-voltage protection (UVP). OVP circuit Using the RDS(ON) of Low-Side MOSFET
which monitors the FB voltage to prevent the PWM output Shutdown Control byCOMP
from over voltage, and UVP circuit which monitors the FB
SOP-8P Package
voltage to prevent the PWM output from under voltage or Lead Free and Green Devices Available
short circuit.The TD1722 is available in SOP-8P packages
Applications
Graphic Cards
DSL, Switch HUB
Wireless Lan
Notebook Computer
Mother Board
LCD Monitor/TV
December, 20, 2011
America Techcode Semiconductor, Inc.
1
www.techcodesemi.com
1 page  
Techcode®
Single Buck Voltage Mode PWM Controller
Absolute Maximum Ratings
DATASHEET
TD1722
Symbol
Parameter
Rating
Unit
VVCC VCC Supply Voltage (VCC to GND)
BOOT Supply Voltage (BOOT to PHASE)
VBOOT
BOOT Supply Voltage (BOOT to GND)
-0.3 ~ 16
-0.3 ~ 16
-0.3 ~ 30
V
V
V
VUGATE
UGATE Voltage (UGATE to PHASE)
> 20ns
< 20ns
-0.3 ~ VBOOT+0.3
-5 ~ VBOOT+5
V
V
VLGATE
LGATE Voltage (LGATE to GND)
> 20ns
< 20ns
-0.3 ~ VVCC+0.3
-5 ~ VVCC+5
V
V
VPHASE
PHASE Voltage (PHASE to GND)
> 20ns
< 20ns
-0.3 ~ 16
-8 ~ 30
V
V
FB and COMP to GND
-0.3 ~ 7
V
POK to GND
-0.3~VCC+0.3
V
TJ Maximum Junction Temperature
150
TSTG Storage Temperature
-65 ~ 150
TSDR Maximum Lead Soldering Temperature, 10 Seconds
260
Note: Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are
°C
°C
°C
stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under "recom- mended operating
conditions" is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Recommended Operating Conditions
Symbol
Parameter
VIN VIN Supply Voltage
VVCC VCC Supply Voltage
VOUT Converter Output Voltage
IOUT Converter Output Current
TA Ambient Temperature
TJ Junction Temperature
Note : Refer to the application circuit for further information.
Range
3.3 ~ 13.2
4.5 ~ 13.2
0.8 ~ 5.5
0 ~ 20
-40 ~ 85
-40 ~ 125
Unit
V
V
V
A
°C
°C
December, 20, 2011
America Techcode Semiconductor, Inc.
5
www.techcodesemi.com
5 Page 
Techcode®
Single Buck Voltage Mode PWM Controller
DATASHEET
TD1722
Function Description
Power-On-Reset (POR)
The Power-On-Reset (POR) function of TD1722 continually
monitors the input supply voltage (VCC) and ensures that the IC
has sufficient supply voltage and can work well. The POR function
initiates a soft-start process while the VCC voltage just exceeds
the POR threshold; the POR function also inhibits the operations
of the IC while the VCC voltage falls below the POR threshold.
Soft-Start
The TD1722 builds in a soft-start function about 1.5ms (Typ.)
interval, which controls the output voltage rising as well as limiting
the current surge at the start-up. During soft-start, an internal ramp
voltage connected to the one of the positive inputs of the error
amplifier replaces the reference voltage (0.8V typical) until the
ramp voltage reaches the reference voltage. The soft-start circuit
interval is shown as figure 1. The UVP function enable delay is
from t2 to t3.
A resistor (ROCSET), connected from the LGATE/OCSET to GND,
programs the over-current trip level. Before the IC initiates a
soft-start process, an internal current source, IOCSET (10A typical),
flowing through the ROCSET develops a voltage (VROCSET) across the
ROCSET. The device holds VROCSET and stops the current source IOCSET
during normal operation. When the voltage across the low-side
MOSFET exceeds the VROCSET, the TD1722 turns off the highside
and low-side MOSFET,and the device will enters hiccup mode
until the over-current phenomenon is released.
The TD1722 has an internal OCP voltage, V ,OCP_MAX and the value
is 0.35V (minimum). When the ROCSET x IOCSET exceed 0.35V or the
ROCSET is floating or not connected, the VROCSET will be the default
value 0.35V. The over current threshold would be 0.35V across
low-side MOSFET. The threshold of the valley inductor
current-limit is therefore given by:
Over-Current Protection of the PWM Converter
The over-current function protects the switching converter against
over-current or short-circuit conditions. The controller senses the
inductor current by detecting the drainto-source voltage which is
the product of the inductor’s current and the on-resistance of the
low-side MOSFET during it’s on-state. This method enhances the
converter’s efficiency and reduces cost by eliminating a current
sensing resistor required.
For the over-current is never occurred in the normal operating load
range, the variation of all parameters in the above equation should
be considered:
- The RDS(ON) of low-side MOSFET is varied by temperature and
gate to source voltage. Users should determine the maximum
RDS(ON) by using the manufacturer’s datasheet.
- The minimum IOCSET (9A) and minimum ROCSET should be used in
the above equation.
- Note that the ILIMIT is the current flow through the lowside
MOSFET; ILIMIT must be greater than valley inductor current which
is output current minus the half of inductor ripple current.
Where I = output inductor ripple current
- The overshoot and transient peak current also should be
considered.
December, 20, 2011
America Techcode Semiconductor, Inc.
11
www.techcodesemi.com
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet TD1722.PDF ] | |
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