ELM91xxxxA CMOS PFM Step-up DC/DC converter and controller
■General description
ELM91xx1xA is CMOS PFM control step-up DC-DC converter; ELM91xx3xA is CMOS PFM control step-
up DC-DC controller, which has large output current capacity by using an external FET switch. ELM91 series
consists of reference voltage source, error amplifier, oscillation circuit, start-up circuit, PFM-control circuit,
switching current limit circuit (ELM91xx1xA only), switching transistor (ELM91xx1xA only) and output
voltage setting resistor. For external parts, coil, diode, MOSFET and capacitor are possible choices. The
standard output voltages are 1.8V,3.0V,3.3V,5.0V; ELM91 series can also be designed as semi-custom IC within
the range of 1.8V to 5.5V by 0.1V step.
■Features
■Application
• Output voltage range : 1.8V to 5.5V (by 0.1V)
• Low voltage operation : 0.9V(ELM91xx1xA: Iout=1mA)
• Oscillating frequency : Typ.100kHz
• Constant voltage source for battery-
operated devices
• Portable communication equipments
and video recorders
• Low power operation : Typ.40µW(ELM91301xA: Typ.100kHz)
• High efficiency
• Output current(e.g.) : 100mA(Vin=1.5V, Vout=3.0V)
• Package : SOT-89, SOT-23, SC-70(SOT-323)
: 85%(ELM9130xxA: Vin=1.5V, Iout=10mA)
■Maximum absolute ratings
Parameter
Apply voltage to LX pin
Apply voltage to VOUT pin
Output current of LX pin
Output current of EXT pin
Symbol
Vlx
Vout
Ilx
Limit
Vss-0.3 to 7.0
Vss-0.3 to 7.0
500
Unit
V
V
mA
mA
Iext
20
500 (SOT-89)
250 (SOT-23)
150 (SC-70)
-40 to +85
-55 to +125
Power dissipation
Pd
mW
Operationg temperature
Storage temperature
Top
Tstg
°C
°C
■Selection guide
ELM91xxxxA-x
Symbol
e.g. :
a, b
c
Output voltage
Switching transistor
Package
18: Vout=1.8V 30: Vout=3.0V
33: Vout=3.3V 50: Vout=5.0V
1: Internal switch
3: External switch
A: SOT-89
B: SOT-23
ELM91 x x x x A - x
↑ ↑ ↑ ↑ ↑ ↑
a b c d e f
d
C: SC-70(SOT-323)
e
f
Product version
Taping direction
A
S , N: Refer to PKG file
22 - 1
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