MIC29201-12BT(1998) Просмотр технического описания (PDF) - Micrel
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MIC29201-12BT Datasheet PDF : 9 Pages
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MIC2920A/29201/29202/29204
Micrel
General Note: Devices are ESD protected; however, handling precautions are recommended.
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not
apply when operating the device outside of its rated operating conditions. The maximum allowable power dissipation is a function of the
maximum junction temperature, TJ , (MAX) the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum
allowable power dissipation at any ambient temperature is calculated using: P(MAX) = (TJ(MAX) – TA) / θJA. Exceeding the maximum allowable
power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The junction to ambient thermal
resistance of the MIC29204BM is 160°C/W mounted on a PC board.
Note 2: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 3: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage due to
heating effects are covered by the thermal regulation specification.
Note 4: Dropout Voltage is defined as the input to output differential at which the output voltage drops 100mV below its nominal value
measured at 1V differential. At low values of programmed output voltage, the minimum input supply voltage of 4.3V over temperature must
be taken into account. The MIC2920A operates down to 2V of input at reduced output current at 25°C.
Note 5: Ground pin current is the regulator quiescent current. The total current drawn from the supply is the sum of the load current plus
the ground pin current.
Note 6: The MIC2920A features fold-back current limiting. The short circuit (VOUT = 0V) current limit is less than the maximum current with
normal output voltage.
Note 7: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding
load or line regulation effects. Specifications are for a 200mA load pulse at V = 20V (a 4W pulse) for T = 10ms.
IN
Note 8: VREF ≤ VOUT ≤ (VIN – 1 V), 4.3V ≤ VIN ≤ 26V, 1 mA < IL ≤400 mA, TJ ≤ TJ MAX.
Note 9: Comparator thresholds are expressed in terms of a voltage differential at the Adjust terminal below the nominal reference voltage
measured at 6V input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT /VREF =
(R1 + R2)/R2. For example, at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output drops by 95
mV x 5V/1.235 V = 384 mV. Thresholds remain constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at typically
5% below nominal, 7.7% guaranteed.
3
Note 10: VSHUTDOWN ≥ 2V, VIN ≤ 26V,VOUT = 0, with Adjust pin tied to 5V Tap or to the R1, R2 junction (see Figure 3) with R1 ≥ 150kΩ.
Note 11: When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode
clamped to ground.
Note 12: Maximum positive supply voltage of 60V must be of limited duration (< 100ms) and duty cycle ( ≤ 1%). The maximum continuous
supply voltage is 26V.
Schematic Diagram
IN
ADJUST
Q15A
Q3
Q6
Q1
10
R1
Q42
20 kΩ
R2
50 kΩ
Q40
Q41
R11
18
kΩ
C1
20
pF
Q4
Q7
Q5
R11
20.6
kΩ
Q2
Q9
Q8
Q20
R8 R10
31.4 kΩ
150
kΩ
R5
R6
R9
180
140
27.8 kΩ
kΩ
kΩ
R12
110
Q13
Q12
kΩ
Q11
R30
30
kΩ
R3
R4
50 kΩ
13 kΩ
50 kΩ
10 kΩ
ERROR
Q37
Q36
Q38
R26
60 kΩ
Q39
Q34
R25
2.8 kΩ
Q15B
Q16 Q17
R17
Q14
12 kΩ
R18
20kΩ
Q26
Q25
Q24
OUT
SENSE
R27
V TAP
R28
Q22
Q21
C2
40 pF
Q23
R15
100 kΩ
R13
100
kΩ
Q18
R14
350
kΩ
Q19
R16
30 kΩ
R17
10 Ω
Q29
Q28
R22
150 kΩ
Q30 Q31
R21 8 Ω
R24 R23 60 kΩ
50 kΩ
SHDN
GND
DENOTES CONNECTION ON
MIC2920A-xx AND MIC29201-xx
VERSIONS ONLY
January 1998
3-13
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