Micro Linear Corporation ML4869ES-3, ML4869ES-5, ML4869CS-3, ML4869CS-5 Datasheet
July 2000
PRELIMINARY
ML4869
Medium Current Boost Regulator
with Load Disconnect
GENERAL DESCRIPTION
The ML4869 is a continuous conduction boost regulator
designed for DC to DC conversion in multiple cell battery
power 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 ML4869
is capable of start-up with input voltages as low as 1.8V,
and is available in 5V and 3.3V output versions with an
output voltage accuracy of ±3%.
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 current and variable
frequency operation result in high efficiency even at light
loads. The ML4869 requires only a few external
components to build a very small regulator capable of
achieving conversion efficiencies approaching 85%.
The SHDN input allows the user to stop the regulator from
switching, and provides complete isolation of the load
from the battery.
FEATURES
■ Guaranteed full load start-up and operation at
1.8V input
■ Continuous conduction mode for high output current
■ Pulse Frequency Modulation and internal synchronous
rectification for high efficiency
■ Isolates the load from the input during shutdown
■ Minimum external components
■ Low ON resistance internal switching FETs
■ Low supply current
■ 5V and 3.3V output versions
■ Shutdown current = 1µA MAX
BLOCK DIAGRAM
V
IN
2
+
–
V
L1
SHDN
1
START-UP
CONTROL
BOOST
PWR GND
6
V
L2
SYNCHRONOUS
RECTIFIER
CONTROL
+
–
2.4V
8
GND
SHUTDOWN
CONTROL
+
–
3
SHDN
V
OUT
4
5
1
ML4869
PIN CONFIGURATION
ML4869
8-Pin SOIC (S08)
V
L1
V
IN
GND
SHDN
PIN DESCRIPTION
PIN NAME FUNCTION
1V
2V
L1
IN
3 GND Ground
4 SHDN Pulling this pin to VIN shuts down the
Boost inductor connection
Battery input voltage
regulator, isolating the load from the
input
1
2
3
4
TOP VIEW
8
7
6
5
PIN NAME FUNCTION
5V
6V
PWR GND
NC
V
L2
V
OUT
OUT
L2
Boost regulator output
Boost inductor connection
7 NC No connection
8 PWR GND Return for the NMOS output transistor
2
ML4869
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.
V
............................................................................................... 7V
OUT
Voltage on any other pin ..... GND - 0.3V to V
Peak Switch Current (I
Average Switch Current (I
) ......................................... 2A
PEAK
)..................................... 1A
AVG
OUT
+ 0.3V
OPERATING CONDITIONS
Temperature Range
ML4869CS-X .............................................. 0°C to 70°C
ML4869ES-X ........................................... -20°C to 70°C
VIN Operating Range .......................1.8V to V
OUT
- 0.2V
Junction Temperature ..............................................150°C
Storage Temperature Range ..................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .....................260°C
Thermal Resistance (qJA).................................... 160°C/W
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, VIN = Operating Voltage Range, TA = Operating Temperature Range (Note 1)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
SUPPLY
I
IN(Q)
I
OUT(Q)VOUT
PFM REGULATOR
I
PEAKIL
V
OUT
SHUTDOWN
V
V
Note 1:
VIN Quiescent Current VIN = V
Peak Current VIN = 2.4V –3 Suffix 700 800 900 mA
Output Voltage I
Load Regulation -3 Suffix, VIN = 2.4V, I
Input Low Voltage 0.5 V
IL
Input High Voltage VIN - 0.5 V
IH
Input Bias Current -100 100 nA
Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions.
- 0.2V, SHDN = 0V 3 6 µA
OUT
VIN = SHDN = 2.4V, V
Quiescent Current SHDN = 0V 25 35 µA
VIN = SHDN = 2.4V 14 20 µA
V
= V
OUT
OUT
See Figure 1 -5 Suffix 4.95 5.05 5.15 V
-5 Suffix, VIN = 2.4V, I
OUT(NOM)
= 0 -3 Suffix 3.30 3.35 3.40 V
= 0V 0.3 1 µA
OUT
–5 Suffix 750 850 950 mA
= 310mA 3.20 3.25 3.40 V
OUT
= 185mA 4.85 4.95 5.15 V
OUT
3
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