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PDF TD8587 Data sheet ( Hoja de datos )
| Número de pieza | TD8587 | |
| Descripción | 1.2MHz Synchronous Boost Converter | |
| Fabricantes | Techcode | |
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Techcode®
5V 2.1A 1.2MHz Synchronous Boost Converter
DATASHEET
TD8587
General Description
Features
The TD8587 is a synchronous rectifier, fixed switching
92%EffiicencySynchronousBoostConverter With
frequency (1.2MHz typical), and current-mode step-up
regulator. The device allows use of small inductors and
1000-mA Output Current From 1.8V Input
Stable with Low ESR Output Capacitors
output capacitors for USB devices. The current-mode control Fixed 1.2MHz Oscillator Frequency
scheme provides fast transient response and good output Low EMI Converter (Integrated Anti-Ringing Function)
voltage accuracy.
Low Battery Output
At light loads, the TD8587 will automatically enter in Pulse Integrated Power SaveModeOperation to Improve Light
Frequency Modulation (PFM) operation to reduce the
Load Efficiency
dominant switching losses. During PFM operation,the IC
consumes very low quiescent current and maintains high
Load Disconnected During Shutdown
Output Current-Limit Protection
efficiency over the complete load range.The TD8587 also
includes current-limit and overtemperature shutdown to
Over Temperature Protection
Under Voltage Protection
prevent damage in the event of an output overload.
The TD8587 is available in ESOP-8 packages.
Enable/ShutdownFunction
Available in ESOP-8 Packages
Lead Free and Green Devices Available(RoHS Compliant)
Applications
Power Bank
Tablet
Portable Equiment
Pin Configurations
October, 20, 2011.
Techcode Semiconductor Limited
1
www.techcodesemi.com
1 page  
Techcode®
5V 2.1A 1.2MHz Synchronous Boost Converter
DATASHEET
TD8587
Electrical Characteristics
Unless otherwise specified, these specifications apply over VBAT=3.3V, VOUT=5V and TA= 25 oC.
Symbol
Parameter
Test Conditions
Converter Supply Voltage
VBAT
Range
VOUT
Converter Output and IC
Supply Voltage
No Switching Quiescent
IDD1
Current
Measured from VOUT, VFB=0.6V, VOUT=3.3V
IVBAT
VBAT Quiescent Current
Measured from VBAT, VBAT=3.3V, EN=H
IVBAT-SD
VBAT Quiescent Current
VEN=GND, VBAT=3.3V (Isolate VBAT & VOUT)
VUVLO
VBAT Under Voltage Lockout
Threshold
VREF
Regulated Feedback Voltage
IFB FB Input Leakage Current
Over Temperature Protection
Hysteresis(note 4)
TJ Falling
FOSC
Switching Frequency
FB=GND
RN-FET
N-FET Switch On Resistance VOUT=5V
RP-FET
P-FET Switch On Resistance VOUT=5V
N-FET Current Limit
VOUT=5V
Dead-time (note 4)
VOUT=3.3V~5V
DMAX
SW Maximum Duty Cycle
PFM Current Limit
EN Input Low Threshold
EN EN Input High Threshold
Internal Pull Low
PSI Input Low Threshold
PSI
PSI Input High Threshold
IEN EN Input Leakage Current VEN=1.5V
IPSI
PSI Input Leakage Current
VPSI=1.5V
VZC P-FET Zero Current Detect
VFB Under Voltage Protection
UVP Debounce
(Option)
Over Temperature Protection
TOTP
TJ Rising
(note 4)
Over Temperature Protection
Hysteresis(note 4)
TJ Falling
Note 4: Guaranteed by design, not production tested.
Min
1.8
3.0
-
-
-
1.6
490
-100
-
900
-
-
4.5
-
80
-
-
1
-
-
1
-
-
-
70
-
-
-
Typ
-
-
40
0.5
0.1
1.7
500
-
30
1200
55
55
5.0
10
85
700
-
-
500
-
-
3
0.4
+100
75
2
150
30
Max
5.5
Unit
V
5.5 V
60
1
1
1.8
510
100
-
1500
-
-
5.5
-
90
-
0.4
-
-
0.4
-
5
1
-
80
-
-
uA
uA
uA
V
mV
nA
OC
MHz
m
m
A
ns
%
mA
V
V
k
V
V
uA
uA
mA
%VREF
us
OC
- OC
October, 20, 2011.
Techcode Semiconductor Limited
5
www.techcodesemi.com
5 Page 
Techcode®
5V 2.1A 1.2MHz Synchronous Boost Converter
Function Description
DATASHEET
TD8587
Main Control Loop
The TD8587 is a constant frequency, synchronous rectifier,
and current-mode switching regulator. In normal operation,
the internal N-channel power MOSFET is turned on each
cycle when the oscillator sets an internal RS latch and turned
off when an internal comparator (ICMP) resets the latch. The
peak inductor current which ICMP resets the RS latch is
controlled by the voltage on the COMP node, which is the
output of the error amplifier (EAMP). An external resistive
divider connected between VOUT and ground allows the EAMP
to receive an output feedback voltage VFB at FB pin. When the
load current increases, it causes a slightly decrease in VFB
relative to the 0.5V reference, which in turn causes the
COMP voltage to increase until the average inductor current
matches the new load current.
Start-up
A start-up oscillator circuit is integrated in the TD8587. When
the device enables, the circuit pumps the output voltage
high. Once the output voltage reaches 1.6V (typ), the main
DC-DC circuitry turns on and boosts the output voltage to the
final regulation voltage.
Automatic PFM/PWM mode Switch
The TD8587 is a fixed frequency PWM peak current
modulation control step-up converter. At light loads, the
TD8587 will automatically enter in pulse frequency
modulation operation to reduce the dominant switching
losses. In PFM operation, the inductor current may reach
zero or reverse on each pulse. A zero current comparator
turns off the P-channel synchronous MOSFET, forcing
DCM(Discontinuous Current Mode) operation at light load.
These controls get very low quiescent current, help to
maintain high efficiency over the complete load range.
Synchronous Rectification
The internal synchronous rectifier eliminates the need for an
external Schottky diode, thus reducing cost and board space.
During the cycle off-time, the P-FET turns on and shunts the
FET body diode. As a result, the synchronous rectifier
significantly improves efficiency without the addition of an
external component. Conversion efficiency can be as high as
92%.
Load Disconnect
Driving EN to ground places the TD8587 in shutdown mode.
When in shutdown, the internal power MOSFET turns off, all
internal circuitry shuts down and the quiescent supply
current reduces to 1A maximum.
A special circuit is applied to disconnect the load from the
input during shutdown the converter. In conventional
synchronous rectifier circuits, the back-gate diode of the
highside P-FET is forward biased in shutdown and allows
current flowing from the battery to the output. However, this
device uses a special circuit, which takes the cathode of the
back-gate diode of the high-side P-FET and disconnects it
from the source when the regulator is shutdown. The benefit
of this feature for the system design engineer is that the
battery is not depleted during shutdown of the converter. No
additional components must be added to the design to make
sure that the battery is disconnected from the output of the
converter.
Current-Limit Protection
The TD8587 monitors the inductor current, flowing through
the N-FET, and limits the current peak at currentlimit level to
prevent loads and the TD8587 from damages during overload
conditions.
Over-Temperature Protection (OTP)
The over-temperature circuit limits the junction temperature
of the TD8587. When the junction temperature exceeds
150oC, a thermal sensor turns off the both N-FET and P-FET,
allowing the devices to cool. The thermal sensor allows the
converters to start a soft-start process and regulate the
output voltage again after the junction temperature cools by
30oC. The OTP is designed with a 30oC hysteresis to lower the
average Junction Temperature (TJ) during continuous thermal
overload conditions, increasing the lifetime of the device.
October, 20, 2011.
Techcode Semiconductor Limited
11
www.techcodesemi.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet TD8587.PDF ] | |
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