MIC2937A Micrel Semiconductor, MIC2937A Datasheet - Page 5

• Manufacturer Part Number: MIC2937A
• Description: 750mA Low-Dropout Voltage Regulator
• Manufacturer: Micrel Semiconductor

MIC2937A/29371/29372
Note 1:
apply when operating the device outside of its rated operating conditions. The maximum allowable power dissipation is a function of the
maximum junction temperature, T
allowable power dissipation at any ambient temperature is calculated using: P
power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.
Note 2:
Note 3:
heating effects are covered by the thermal regulation specification.
Note 4:
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 MIC2937A operates down to 2V of input at reduced output current at 25 C.
Note 5:
the ground pin current.
Note 6:
with normal output voltage.
Note 7:
load or line regulation effects. Specifications are for a 200mA load pulse at V
Note 8:
Note 9:
measured at 6V input (for a 5V regulator). To express these thresholds in terms of output voltage change, multiply by the error amplifier gain
= V
drops by 95 mV x 5V/1.235 V = 384 mV. Thresholds remain constant as a percent of V
occurring at typically 5% below nominal, 7.7% guaranteed.
Note 10: Circuit of Figure 3 with R1
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
MIC2937A/29371/29372
OUT
/V
REF
Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage due to
Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value
Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus
The MIC2937A family features fold-back current limiting. The short circuit (V
Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding
V
Comparator thresholds are expressed in terms of a voltage differential at the Adjust terminal below the nominal reference voltage
REF
= (R1 + R2)/R2. For example, at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output
V
OUT
(V
IN
50 k
10 k
– 1 V), 4.3V
Q42
Q40
J (MAX)
R30
k
Q6
30
50 k
20 k
Q41
, the junction-to-ambient thermal resistance,
R2
R1
150k . V
10
Q1
Q3
50 k
R3
V
R11
18
k
ERROR
180
IN
IN
R5
k
C1
20
pF
Q13
SHUTDOWN
13 k
R4
26V, 5mA < I
140
R6
k
Q4
Q38
Q12
Q39
Q2
Q5
Q37
31.4 k
27.8 k
20.6
R11
R8
R9
Q15A
k
R26
60 k
Q7
Q11
Q36
2V and V
R10
150
k
L
Q8
R25
2.8 k
750 mA, T
22
Q9
Q34
IN
R12
110
k
Q20
26V,V
Q18
IN
J
R13
GND
Q16
100
k
(MAX)
= 20V (a 4W pulse) for T = 10ms.
R22
150 k
T
Q15B
OUT
J MAX.
Q17
= (T
R14
350
k
C2
40 pF
OUT
= 0.
JA
, and the ambient temperature, T
J(MAX)
Q30
Q19
= 0V) current limit is less than the maximum current
Q14
DENOTES CONNECTION ON
MIC2937A-xx AND MIC29371-xx
VERSIONS ONLY
OUT
Q31
Q21
– T
FEEDBACK
12 k
Q29
R17
as V
A
R24
50 k
) /
Q28
OUT
Q22
R15
100 k
R16
30 k
JA.
Q25
R23 60 k
R21 8
Exceeding the maximum allowable
R18
20k
is varied, with the dropout warning
Q26
10
R17
Q23
SHDN
R27
R28
Q24
SENSE
V TAP
OUT
A
. The maximum
October 1999
Micrel