|
|
Part: ML4771ES
Category:
Power Management
Description: High Current Boost Regulator
Company: Micro Linear
Datasheet: Download ML4771ES datasheet File size : 5795 kB
Request For quote: Find where to buy ML4771ES
Datasheet text preview:
July 2000
ML4771* High Current Boost Regulator
GENERAL DESCRIPTION
The ML4771 is a continuous conduction boost regulator designed for DC to DC conversion in multiple cell battery powered systems. Continuous conduction allows the regulator to maximize output current for a given inductor. The maximum switching frequency can exceed 200kHz, allowing the use of small, low cost inductors. The ML4771 is capable of start-up with input voltages as low as 1.8V, and the output voltage can be set anywhere between 3.0V and 5.5V by an external resistor divider connected to the SENSE pin. An integrated synchronous rectifier eliminates the need for an external Schottky diode and provides a lower forward voltage drop, resulting in higher conversion efficiency. In addition, low quiescent battery current and variable frequency operation result in high efficiency even at light loads. The ML4771 requires a minimum number of external components to build a very small regulator circuit capable of achieving conversion efficiencies exceeding 85%.
FEATURES
s
Guaranteed full load start-up and operation at 1.8V input Continuous conduction mode for high output current Very low supply current (20µA output referenced) for micropower operation Pulse Frequency Modulation and Internal Synchronous Rectification for high efficiency Maximum switching frequency > 200kHz Minimum external components Low ON resistance internal switching FETs Adjustable output voltage (3.0V to 5.5V)
s s
s
s s s s
(* Indicates Part is End Of Life as of July 1, 2000)
BLOCK DIAGRAM
L1
1 VL1 VIN 2 *CIN
6 VL2
VOUT 5 VOUT
R1 VBAT
COUT
GND 3
BOOST CONTROL
SENSE 4 R2
*CFB
PWR GND 8
1
ML4771
PIN CONFIGURATION
ML4771 8-Pin SOIC (S08)
VL1 VIN GND SENSE 1 2 3 4 TOP VIEW 8 7 6 5 PWR GND NC VL2 VOUT
PIN DESCRIPTION
PIN NAME FUNCTION PIN NAME FUNCTION
1 2 3 4
VL 1 VIN GND SENSE
Boost inductor connection Battery input voltage Ground Programming pin for setting the output voltage
5 6 7 8
VOUT VL 2 NC
Output of the boost regulator Boost inductor connection No connection
PWR GND Return for the NMOS output transistor
2
ML4771
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. VOUT ......... 7V Voltage on any other pin ..... GND 0.3V to VOUT + 0.3V Peak Switch Current (IPEAK) ......... 2A Average Switch Current (IAVG) .... 1A Junction Temperature .... 150ºC Storage Temperature Range.... 65ºC to 150ºC Lead Temperature (Soldering 10 sec) ..... 260ºC Thermal Resistance (qJA) ... 160ºC/W
OPERATING CONDITIONS
Temperature Range ML4771CS ....... 0ºC to 70ºC ML4771ES ............ 20ºC to 70ºC VIN Operating Range ML4771CS ... 1.8V to VOUT 0.2V ML4771ES ... 2.0V to VOUT 0.2V VOUT Operating Range ......... 3.0V to 5.5V
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, VIN = Operating Voltage Range, TA = Operating Temperature Range (Note 1).
SYMBOL SUPPLY I IN IOUT(Q) IL ( Q ) VIN Current VOUT Quiescent Current VL Quiescent Current VIN = VOUT 0.2V 2 25 5 35 1 µA µA µA PARAMETER CONDITIONS MIN TYP MAX UNITS
PFM REGULATOR IL Peak Current VSENSE VOUT SENSE Comparator Threshold Voltage Output Voltage Load Regulation See Figure 1, IOUT = 0 See Figure 1, VIN = 2.4V, IOUT = 220mA 1.2 2.52 4.95 4.85 1.4 2.57 5.05 4.95 1.7 2.62 5.15 5.15 A V V V
Note 1:
Limits are guaranteed by 100% testing, sampling or correlation with worst case test conditions.
3
Others parts begin by ml
|
|
|
