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PDF TD1729 Data sheet ( Hoja de datos )
| Número de pieza | TD1729 | |
| Descripción | High-Performance PWM Controller | |
| Fabricantes | Techcode | |
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Techcode®
High-Performance PWM Controller
DATASHEET
TD1729
General Description
Features
The TD1729 is a single-phase, constant-on-time,
synchronous PWM controller, which drives N-channel
MOSFETs. The TD1729 steps down high voltage to
generate low-voltage chipset or RAM supplies in notebook
computers.
The TD1729 provides excellent transient response and
accurate DC voltage output in either PFM or PWM Mode. In
Pulse Frequency Mode (PFM), the TD1729 provides very high
efficiency over light to heavy loads with loading- modulated
switching frequencies. In PWM Mode, the converter works
nearly at constant frequency for low-noise requirements.
The TD1729 is equipped with accurate positive current- limit,
output under-voltage, and output over-voltage
protections, perfect for NB applications. The Power-On-
Reset function monitors the voltage on VCC to prevent
wrong operation during power-on. The TD1729 has a 1ms
digital soft-start and built-in an integrated output
discharge method for soft-stop. An internal integrated
soft-start ramps up the output voltage with programmable
slew rate to reduce the start-up current. A soft-stop function
actively discharges the output capacitors with controlled
reverse inductor current.
The TD1729 is available in 10pin TDFN 3x3 package.
Adjustable Output Voltage from +0.7V to +5.5V
0.7V Reference Voltage
±1% Accuracy Over-Temperature
Operates from an Input Battery Voltage Range of +1.8V
to +32V
Power-On-Reset Monitoring on VCC Pin
Excellent Line and Load Transient Responses
PFM Mode for Increased Light Load Efficiency
Selectable PWM Frequency from 4 Preset Values
Integrated MOSFET Drivers
Integrated Bootstrap Forward P-CH MOSFET
Adjustable Integrated Soft-Start and Soft-Stop
Selectable Forced PWM or Automatic PFM/PWM Mode
Power Good Monitoring
70% Under-Voltage Protection
125% Over-Voltage Protection
Adjustable Current-Limit Protection
Using Sense Low-Side MOSFET’s RDS(ON)
Over-Temperature Protection
Auto Rework from Protection Mode
TDFN-10 3x3 Package
Lead Free and Green Devices Available (RoHS Compliant)
Applications
Notebook
Table PC
Hand-Held Portable
AIO PC
LCD Monitor / TV
Battery Charger
ADSL Modem
Telecom / Networking Equipment
December, 20, 2011
Techcode Semiconductor Limited
1
www.techcodesemi.com
1 page  
Techcode®
High-Performance PWM Controller
Electrical Characteristics
DATASHEET
TD1729
Refer to the typical application circuit. These specifications apply over VVCC = 12V, TA = -40°C to 85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Parameter
Test Conditions
VOUT
VREF
IFB
TDIS
IVCC
IVCC_SHDN
VOUT AND VFB VOLTAGE
Output Voltage
Adjustable output range
Reference Voltage
Regulation Accuracy
TA = 25 oC
TA = 0 oC ~ 85 oC
TA = -40 oC ~ 85 oC
FB Input Bias Current
FB = 0.7V
VOUT Discharge Time
EN low to FB = 0V
SUPPLY CURRENT
VCC Input Bias Current
VCC Shutdown Current
VCC Current, PWM, EN = 5V, VFB = 0.735V, PHASE =
0.5V
EN = GND, VCC = 5V
SWITCHING FREQUENCY AND SUTY AND INTERNAL SOFT-START
RRF = 470k , TA = 25oC, VIN=8V, VOUT=1.1V, IOUT=10A
RRF = 200k , TA = 25oC, VIN=8V, VOUT=1.1V, IOUT=10A
FSW Switching Frequency
RRF = 100k , TA = 25oC, VIN=8V, VOUT=1.1V, IOUT=10A
RRF = 39k , TA = 25oC, VIN=8V, VOUT=1.1V, IOUT=10A
TD1729
Unit
Min. Typ. Max.
0.7
- 5.5
V
- 0.7
-V
-0.5 -
+0.5 %
-0.8 -
+0.8 %
-1.0 -
+1.0 %
- 0.02 0.1
uA
- 12
- ms
- 250 520 uA
- 01
.
266 290 3140
312 340 368
349 380 411
395 430 465
uA
kHz
TON(MIN) Minimum On Time
TOFF(MIN) Minimum Off Time
VFB = 0.65V, VPHASE = -0.1V, OCSET = OPEN
80 110 140
350 450 550
ns
ns
TSS Internal Soft-Start Time
UGATE Pull-Up Resistance
UGATE Sink Resistance
LGATE Pull-Up Resistance
LGATE Sink Resistance
UGATE to LGATE Dead-Time
LGATE to UGATE Dead-Time
VF Ron
IR Reverse Leakage
EN High to VOUT Regulation (95%)
GATE DRIVER
BOOT-UGATE = 0.5V
UGATE-PHASE = 0.5V
PVCC-LGATE = 0.5V
LGATE-GND = 0.5V
UGATE falling to LGATE rising
LGATE falling to UGATE rising
BOOTSTRAP SWITCH
VVCC - VBOOT-GND, IF = 10mA
VBOOT-GND = 30V, VPHASE = 25V, VVCC = 5V
0.7 1.0 1.3
ms
- 1.5
- 0.7
- 1.0
- 0.5
- 20
- 20
3
1.8
2.2
1.2
-
-
ns
ns
- 0.5 0.8
- - 0.5
V
uA
VVCC_THR Rising VSS POR Threshold
VCC POR Hysteresis
EN Voltage Threshold
VCC POR THRESHOLD
Enable
Shutdown
CONTROL INPUTS
4.2 4.35 4.45
- 100
-
V
mV
1.8 - - V
-
- 0.5
V
December, 20, 2011
Techcode Semiconductor Limited
5
www.techcodesemi.com
5 Page 
Techcode®
High-Performance PWM Controller
DATASHEET
TD1729
Function Description(Cont.)
switching frequency.
During soft-start stage before the PGOOD pin is ready,the
under-voltage protection is prohibited. The over-voltage and
current-limit protection functions are enabled. If the output capacitor
has residue voltage before start-up, both low-side and high-side
MOSFETs are in off-state until the internal digital soft-start voltage
equals to the VFB voltage. This will ensure that the output voltage starts
from its existing voltage level.In the event of under-voltage,
over-temperature, or shutdown, the chip enables the soft-stop
function. The soft-stop function discharges the output voltage to the
GND. The duration of the discharge time is 8ms.
Power OK Indicator
The TD1729 features an open-drain POK pin to indicate output
regulation status. In normal operation, when the output voltage rises
90% of its target value, the POK goes high after 63us internal delay.
When the output voltage outruns 70% or 125% of the target voltage,
POK signal will be pulled low immediately.
Since the FB pin is used for both feedback and monitoring purposes, the
output voltage deviation can be coupled directly to the FB pin by the
capacitor in parallel with the voltage divider as shown in the typical
applications. In order to prevent false POK from dropping, capacitors
need to parallel at the output to confine the voltage deviation with
severe load step transient.
Under-Voltage Protection (UVP)
In the operational process, if a short-circuit occurs, the output voltage
will drop quickly. When load current is bigger than current-limit
threshold value, the output voltage will fall out of the required
regulation range. The undervoltage protection circuit continually
monitors the FB voltage after soft-start is completed. If a load step is
strong enough to pull the output voltage lower than the undervoltage
threshold, the under-voltage threshold is 70% of the nominal output
voltage, the internal UVP delay counter starts to count. After 16s
debounce time, the device turns off both high-side and low-side
MOSEFET with latched and starts a soft-stop process to shut down the
output gradually. Toggling enable pin to low or recycling VCC,will clear
the latch and bring the chip back to operation.When Short-circuit is’t
occurs the chip can auto rework.
Over-Voltage Protection (OVP)
The over-voltage function monitors the output voltage by FB pin. When
the FB voltage increases over 125% of the reference voltage due to the
high-side MOSFET failure or for other reasons, the over-voltage
protection comparator designed with a 1.5s noise filter will force the
lowside MOSFET gate driver fully turn on and latch high. This action
actively pulls down the output voltage.This OVP scheme only clamps
the voltage overshoot and does not invert the output voltage when
otherwise activated with a continuously high output from low-side
MOSFET driver. It’s a common problem for OVP schemes with a latch.
Once an over-voltage fault condition is set, it can only be reset by
toggling EN, VCC power-on-reset signal.The chip will auto rework when
Voltage normal.
Current-Limit
The current-limit circuit employs a “valley” current-sensing algorithm
(See Figure 2). The TD1729 uses the low-side MOSFET’s RDS(ON) of the
synchronous rectifier as a current-sensing element. If the magnitude of
the current-sense signal at PHASE pin is above the currentlimit
threshold, the PWM is not allowed to initiate a new cycle. The actual
peak current is greater than the currentlimit threshold by an amount
equals to the inductor ripple current. Therefore, the exact current-limit
characteristic and maximum load capability are the functions of the
sense resistance, inductor value, and input voltage.
December, 20, 2011
Techcode Semiconductor Limited
11
www.techcodesemi.com
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet TD1729.PDF ] | |
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