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Part: ML4790
Category:
Power Management
-> Regulators
Description: Adjustable Output, Low Ripple Boost Regulator
Company: Micro Linear
Datasheet: Download ML4790 datasheet File size : 5795 kB
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Datasheet text preview:
ed Extend for
INGRange e TUR EAmercial Temperatur F
C Com to 70° ent 20°C held Equipm d le Han Portab
July 2000
ML4790*
Adjustable Output, Low Ripple Boost Regulator
GENERAL DESCRIPTION
The ML4790 is a high efficiency, PFM (Pulse Frequency Modulation), boost switching regulator connected in series with an integrated LDO (Low Dropout Regulator) that incorporates "Silent SwitcherTM" technology. This technique incorporates a patented tracking scheme to minimize the voltage drop across the LDO and increase the total efficiency of the regulator beyond that which can be obtained by using a discrete external LDO regulator. The ML4790 is designed to convert single or multiple cell battery inputs to regulated output voltages for integrated circuits and is ideal for portable communications equipment that cannot tolerate the output voltage ripple normally associated with switching regulators. An integrated synchronous rectifier eliminates the need for an external Schottky diode and provides a lower forward voltage drop, resulting in higher conversion efficiency.
FEATURES
Incorporates "Silent SwitcherTM" technology to deliver very low output voltage ripple (typically 5mV) s Guaranteed full load start-up and operation at 1.0V input and low operating quiescent current (<100µA) for extended battery life
s s s
Pulse Frequency Modulation and internal synchronous rectification for high efficiency
Minimum external components s Low ON resistance internal switching MOSFETs
s
Adjustable output voltage (2.5V to 5.5V)
(* Indicates Part is End Of Life as Of July 1, 2000)
BLOCK DIAGRAM
L1
*CIN
VIN
C2 1 VL 6 5 VBOOST
VBAT 7
SHDN VOUT 4 BOOST CONTROL FEEDBACK LDO CONTROL R1 SENSE 3 R2 8 2 GND PWR GND VOUT CFB COUT + VOUT
FROM POWER MANAGEMENT
Patent Pending *Optional
1
ML4790
PIN CONNECTION
ML4790 8-Pin SOIC (S08N)
VIN GND SENSE VOUT
1 2 3 4 8 7 6 5
PWR GND SHDN VL VBOOST
TOP VIEW
PIN DESCRIPTION
PIN NO. PIN NO.
NAME
FUNCTION
NAME
FUNCTION
1 2 3 4
VIN GND SENSE VOUT
Battery input voltage Analog signal ground Programming pin for setting the output voltage LDO linear regulator output
5 6 7
VBOOST VL SHDN
Boost regulator output for connection of an output filter capacitor Boost inductor connection Pulling this pin high shuts down the regulator, isolating the load from the input
8
PWR GND Return for the NMOS boost transistor
2
ML4790
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. VBOOST ...... 7V Voltage on Any Other Pin ... GND 0.3V to VBOOST +0.3V Peak Switch Current (IPEAK) ......... 1A Average Switch Current (IAVG) ....... 500mA LDO Output Current ............ 250mA Junction Temperature .... 150°C Storage Temperature Range ........... 65°C to +150°C Lead Temperature (Soldering 10s) .. +260°C Thermal Resistance (JA) Plastic SOIC .... 110°C/W
OPERATING CONDITIONS
Temperature Range ML4790CS-X ........... 0°C to +70°C ML4790ES-X ........ 20°C to +70°C VIN Range ML4790CS-X ...... 1.0V to 6V ML4790ES-X ....... 1.1V to 6V VOUT Range ........ 2.5V to 5.5V
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, VIN = Operating Voltage Range, TA = Operating Temperature Range. (Note 1)
PARAMETER Supply VIN Current VIN = 6V SHDN = high VOUT Quiescent Current VL Quiescent Current PFM Regulator Pulse Width (TON) LDO SENSE Comparator Threshold Voltage Load Regulation See Figure 1 VIN = 1.2V, IOUT < 10mA VIN = 2.4V, IOUT < 75mA See Figure 1 VIN = 1.2V, IOUT < 10mA VIN = 2.4V, IOUT < 75mA 5 194 4.85 4.85 200 5.0 5.0 206 5.15 5.15 300 500 mV V V mV mV mVP-P 4.5 5 5.5 µs VBOOST = VOUT + 0.5V 60 15 8 75 25 10 1 µA µA µA µA CONDITIONS MIN TYP. MAX UNITS
Dropout Voltage
Output Ripple Shutdown SHDN Threshold SHDN Bias Current
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions.
22µH (Sumida CD54)
0.5 100
0.8
1.0 100
V nA
ML4790
VIN 100µF 1nF 931k 39.2k 100µF VIN GND SENSE VOUT PWR GND SHDN VL VBOOST IOUT VOUT 33µF
Figure 1. Application Test Circuit
3
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