Current Regulator. MCP1643 Datasheet

MCP1643 Regulator. Datasheet pdf. Equivalent

MCP1643 Datasheet
Recommendation MCP1643 Datasheet
Part MCP1643
Description 1 MHz Low Start-up Voltage Synchronous Boost LED Constant Current Regulator
Feature MCP1643; MCP1643 1 MHz Low Start-up Voltage Synchronous Boost LED Constant Current Regulator Features • 1.6A.
Manufacture Microchip
Datasheet
Download MCP1643 Datasheet





Microchip MCP1643
MCP1643
1 MHz Low Start-up Voltage Synchronous Boost
LED Constant Current Regulator
Features
• 1.6A Typical Peak Input Current Limit
• Up to 550 mA LED Load Current
• Low Start-up Voltage: 0.65V (typical, 25 mA LED
Current)
• Low Operating Input Voltage: down to 0.5V
• Maximum Input Voltage < VLED < 5.0V
• Maximum Output Voltage:
- 5.0V
- Overvoltage Protection
• Low Reference Voltage:
- VFB = 120 mV
- Minimal Power Loss on Sense Resistor
• Pulse-Width Modulation Mode Operation (1 MHz)
• Internal Synchronous Rectifier
• Internal Compensation
• Inrush Current Limiting
• Internal Soft-Start (240 µs typical)
• Shutdown (EN = GND):
- True Load Disconnect
- Dimming Control by Variable Duty Cycle
• Shutdown Current: 1.2 µA (typical)
• Overtemperature protection
• Packages:
- MSOP-8
- 2x3 DFN-8
Applications
• One and Two Cell Alkaline and NiMH/NiCd
Portable LED Lighting Products
• LED Flashlight and Head Lamps
• Rechargeable Flashlights
• Wall LED Lamps with Motion Detectors
• LED supply for backlights
• General LED constant current applications
Description
MCP1643 is a compact, high-efficiency, fixed
frequency, synchronous step-up converter optimized to
drive one LED with constant current, that operates from
one and two-cell alkaline and NiMH/NiCd batteries.
The device can also drive two red/green/yellow series
connection LEDs.
Low-voltage technology allows the regulator to start up
without high-output voltage and load-current overshoot
from a low 0.65V input. High efficiency is accomplished
by integrating the low resistance N-Channel Boost
switch and synchronous P-Channel switch. All
compensation and protection circuitry are integrated to
minimize external components.
The internal feedback (VFB) voltage is set to 120 mV for
low power dissipation when sensing and regulating
LED current. A single resistor sets the constant current
output that drives the LED load.
The device features an output overvoltage protection
that limits the output voltage to 5.0V typical, in case the
LED fails or output load is disconnected.
The LED will either be turned OFF or turned ON using
the enable input. A True Output Load Disconnect mode
provides input-to-output isolation while Shutdown
(EN = GND) by removing the normal boost regulator
diode path from input to output. Shutdown state
consumes 1.2 µA from input at room temperature.
The LED can be turned on and off with a variable duty
cycle pulse-width modulation (PWM) signal applied to
the EN pin for dimming applications.
The device also features a thermal shutdown at
+150°C, with +25°C hysteresis.
Two package options, MSOP-8 and 2x3 DFN-8, are
available.
Package Types
MCP1643
MSOP-8
MCP1643
2x3 DFN*
EN 1
VFB 2
NC 3
VOUT 4
8 VIN EN 1
8 VIN
7 SGND VFB 2 EP 7 SGND
6
PGNDVONUCT
3
4
9
6 PGND
5 SW
5 SW
* Includes Exposed Thermal Pad (EP), see Table 3-1.
2013 Microchip Technology Inc.
DS20005208A-page 1



Microchip MCP1643
MCP1643
Typical Applications
CIN
4.7...10 µF
+
-
ON
OFF
L1
4.7 µH
ILED = R-0---.-S-1---2E----V-T--
SW ILED = 25 mA
VOUT
VIN
LED
MCP1643
VFB
EN
GND
RSET
4.7
COUT
4.7 µF
L1
4.7 µH
CIN
4.7...10 µF
+
-
ON/OFF
+
REN
1 M
SW
VOUT
VIN
MCP1643
VFB
EN GND
WHITE LED
ILED = 360 mA
RSET
0.33
COUT
20 µF
-
RSET Minimum and Maximum Limits for ILED in Regulation, with ±6% Tolerance
10
RSET for ILED MIN
IILLEEDD
MAX
MAX
1000
1 100
RSET for ILED MAX
0.1
0.6
ILIELDEMDINMIN
0.9 1.2
WHITE LED
TA = +25oC 10
1.5 1.8 2.1 2.4 2.7 3
Input Voltage (V)
DS20005208A-page 2
2013 Microchip Technology Inc.



Microchip MCP1643
MCP1643
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings †
EN, FB, VIN, VSW, VOUT - GND ........................... +6.5V
EN, FB ......... < maximum VOUT or VIN > (GND – 0.3V)
Output Short Circuit Current....................... Continuous
Power Dissipation ............................ Internally Limited
Storage Temperature ......................... -65°C to +150°C
Ambient Temp. with Power Applied...... -40°C to +85°C
Operating Junction Temperature........ -40°C to +125°C
ESD Protection On All Pins:
HBM .............................................................. 4 kV
MM................................................................ 300V
† Notice: Stresses above those listed under “Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of
the device at those or any other conditions above those
indicated in the operational sections of this
specification is not intended. Exposure to maximum
rating conditions for extended periods may affect
device reliability.
DC CHARACTERISTICS
Electrical Characteristics: Unless otherwise indicated, VIN = EN = 1.2V, COUT = 20 µF, CIN = 10 µF, L = 4.7 µH,
ILED = 25 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
Parameters
Sym
Min Typ
Max Units
Conditions
Input Characteristics
Minimum Input Voltage
After Start-Up
VIN
— 0.5
— V Note 1, Note 3
Start-Up Voltage
Output Overvoltage
Protection
VIN — 0.65 0.8 V Note 2, Note 1
VOUT_OVP
5.0
— V Note 3
Shutdown
Quiescent Current
IQSHDN — 1.2
— µA EN = GND;
includes N-Channel and
P-Channel Switch Leakage
Feedback Voltage
Feedback Input
Bias Current
VFB
IVFB
105 120
— 60
135 mV
— pA
NMOS Switch Leakage
PMOS Switch Leakage
NMOS Switch
ON Resistance
INLK
— 0.4
IPLK — 0.25
RDS(ON)N
0.2
— µA VIN = VSW = 4.0V
VOUT = 4.5V
VEN = VFB = GND
— µA VIN = VSW = GND;
VOUT = 4.5V
ILED = 250 mA, Note 3
PMOS Switch
ON Resistance
RDS(ON)P
0.4
ILED = 250 mA, Note 3
NMOS Peak
Switch Current Limit
IN(MAX)
— 1.6
— A Note 3
Maximum Duty Cycle
DCMAX — 90
— % Note 3
Minimum Duty Cycle
DCMIN — 5
— % Note 3
Switching Frequency
fSW
0.85 1.0
1.15 MHz
EN Input Logic High
VIH 75 — — %of VIN ILED= 25 mA
EN Input Logic Low
VIL
——
20 %of VIN ILED = 25 mA
Note 1: For VIN < VOUT, ILED remains in regulation up to VIN = VLED minus a headroom @ LED typical VF and IF.
2: VOUT completely discharged. If the output capacitor remains partially charged, the device will start-up at
the minimum possible voltage.
3: Determined by characterization, not production tested.
2013 Microchip Technology Inc.
DS20005208A-page 3





@ 2014 :: Datasheetspdf.com :: Semiconductors datasheet search & download site (Privacy Policy & Contact)