Micro Linear Corporation ML4790CS, ML4790ES Datasheet
July 2000
FEATURING
Extended Commercial Temperature Range
–20°C to 70°C
for Portable Handheld Equipment
BOOST
CONTROL
4
8
2
1
6
L1
SHDN
V
IN
GND
FEEDBACK
V
L
+
–
V
OUT
PWR
GND
FROM
POWER
MANAGEMENT
*C
IN
V
BAT
7
LDO
CONTROL
5
V
BOOST
C2
V
OUT
3
SENSE
R
1
R
2
C
OUT
V
OUT
C
FB
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 Switcher™” 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
FEATURES
■ Incorporates “Silent Switcher™” technology to deliver
very low output voltage ripple (typically 5mV)
■ Guaranteed full load start-up and operation at 1.0V
input and low operating quiescent current (<100µA)
for extended battery life
■Pulse Frequency Modulation and internal synchronous
rectification for high efficiency
■ Minimum external components
■ Low ON resistance internal switching MOSFETs
■ Adjustable output voltage (2.5V to 5.5V)
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. (* Indicates Part is End Of Life as Of July 1, 2000)
BLOCK DIAGRAM
Patent Pending
*Optional
1
ML4790
PIN CONNECTION
ML4790
8-Pin SOIC (S08N)
PIN DESCRIPTION
V
GND
SENSE
V
OUT
IN
1
2
3
4
TOP VIEW
8
7
6
5
PWR GND
SHDN
V
L
V
BOOST
PIN
NO. NAME FUNCTION
1V
IN
Battery input voltage
2 GND Analog signal ground
3 SENSE Programming pin for setting the
output voltage
4V
OUT
LDO linear regulator output
PIN
NO. NAME FUNCTION
5V
BOOST
Boost regulator output for connection
of an output filter capacitor
6V
L
Boost inductor connection
7 SHDN 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
Storage Temperature Range .................... –65°C to +150°C
Lead Temperature (Soldering 10s).......................... +260°C
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.
V
Voltage on Any Other Pin ...GND –0.3V to V
Peak Switch Current (I
Average Switch Current (I
........................................................................ 7V
BOOST
) .......................................... 1A
PEAK
) ............................... 500mA
AVG
BOOST
+0.3V
LDO Output Current ............................................. 250mA
Junction Temperature .............................................. 150°C
Thermal Resistance (θ
Plastic SOIC .................................................... 110°C/W
OPERATING CONDITIONS
Temperature Range
ML4790CS-X ............................................ 0°C to +70°C
ML4790ES-X......................................... –20°C to +70°C
V
Range
IN
ML4790CS-X ................................................ 1.0V to 6V
ML4790ES-X................................................. 1.1V to 6V
V
Range .................................................. 2.5V to 5.5V
OUT
)
JA
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, V
PARAMETER CONDITIONS MIN TYP. MAX UNITS
Supply
VIN Current VIN = 6V 60 75 µA
V
Quiescent Current V
OUT
VL Quiescent Current 1 µA
= Operating Voltage Range, TA = Operating Temperature Range. (Note 1)
IN
SHDN = high 15 25 µA
BOOST
= V
+ 0.5V 8 10 µA
OUT
PFM Regulator
Pulse Width (TON) 4.5 5 5.5 µs
LDO
SENSE Comparator Threshold Voltage 194 200 206 mV
Load Regulation See Figure 1
= 1.2V, I
V
IN
VIN = 2.4V, I
< 10mA 4.85 5.0 5.15 V
OUT
< 75mA 4.85 5.0 5.15 V
OUT
Dropout Voltage See Figure 1
= 1.2V, I
V
IN
VIN = 2.4V, I
Output Ripple 5mV
< 10mA 300 mV
OUT
< 75mA 500 mV
OUT
P-P
Shutdown
SHDN Threshold 0.5 0.8 1.0 V
SHDN Bias Current –100 100 nA
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions.
22µH
(Sumida CD54)
ML4790
V
IN
100µF
1nF
931kΩ
39.2kΩ
V
IN
GND
SENSE
V
OUT
PWR GND
SHDN
V
BOOST
100µF
V
L
33µF
I
OUT
V
OUT
Figure 1. Application Test Circuit
3
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