CM2730 Datasheet, PDF (5/10 Pages) List of Unclassifed Manufacturers – 300mA DUAL LOW NOISE CMOS LDO

CM2730
300mA DUAL LOW NOISE CMOS LDO
ELECTRICAL CHARACTERISTICS (CONTI.)
TA = +25℃; unless otherwise noted
Parameter
Test Conditions
CM2730
Unit
Min. Typ. Max.
PGB (Note2)
VIN1>VIN1(MIN), VIN2>VIN2(MIN) ,ENB=GND,
VOUT1>0.95VOUT1, VOUT2>0.95VOUT2,
VIN1>VIN1(MIN), VIN2>VIN2(MIN) ,ENB=GND,
VOUT1<0.78VOUT1, or VOUT2<0.78VOUT2
0.1 V
VIN1
V
LDO2 Turn on Threshold Voltage (Vo1)
ENB=0, VIN1>VIN1(MIN), VIN2>VIN2(MIN)
0.95VOUT1
LDO2 Turn off Threshold Voltage (Vo1)
ENB=0, VIN1>VIN1(MIN), VIN2>VIN2(MIN)
0.78VOUT1
ENB Input Threshold
VSH
VSL
VIN1=2.6V to 7V
VIN1=2.6V to 7V
VIN1/2+0.8
V
VIN1/2-0.8
V
Note 1. VIN(MIN) = VOUT + Dropout Voltage
Note 2: Dual LDO contains 2 LDO, one is fix output voltage 2.5V or 3.3V (2 versions), which is master LDO1, the other is
adjustable output voltage, which is slave LDO2. At normal operation condition, master LDO1 turns on first, and then slave LDO2
turns on as master LDO1 output voltage reaches to 95% spec. VOUT1. Slave LDO2 will turn off as master output decreases to
78% spec. VOUT1.
DETAILED DESCRIPTION
The CM2730 family of CMOS regulators provide a preset output voltage LDO (master LDO1), and one adjustable output voltage
LDO (slave LDO2) in which each contains p-channel pass transistor, voltage reference, error amplifier, over-current protection,
thermal shutdown, and short circuit protection.
CM2730 has a power sequence. When master LDO1’s output voltage, which is preset value in design, reaches to its 95~96%
nominal output value, internal logic circuits begin to enable the slave LDO2 function which is adjustable output voltage. When
both LDO output voltage values are larger than 95% of their nominal output voltage values, the PGB will go low.
The P-channel pass transistor receives data from the error amplifier, over-current shutdown, short output protection, and thermal
protection circuits. During normal operation, the error amplifier compares the output voltage to a precision reference. Over-current
and Thermal shutdown circuits become active when the junction temperature exceeds 150℃, or the current exceeds 300mA.
During thermal shutdown, the output voltage remains low. Normal operation is restored when the junction temperature drops
below 120℃.
The CM2730 switches from voltage mode to current mode when the load exceeds the rated output current. This prevents
over-stress. The CM2730 also incorporates current fold-back to reduce power dissipation when the output is short-circuited. This
feature becomes active when the output drops below 0.95V, and reduces the current flow by 65%. Full current is restored when
the voltage exceeds 0.95V.
EXTERNAL CAPACITOR
The CM2730 is stable with output capacitors to ground of 2.2µF or greater. It can keep stable even with higher or poor ESR
capacitors. A capacitor is recommended between the input and ground to stabilize each input voltage. The input capacitor should
be larger than 0.1µF to have a beneficial effect. All capacitors should be placed in close proximity to the pins. A “quiet” ground
termination is desirable.
2002/09/30 Preliminary Rev. 0.3
Champion Microelectronic Corporation
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