How it Works
Datasheet
Loading...
MIC29712BT
Datasheet (MICREL)
8 pgs82.92 Kb0

Datasheet MIC29712BT, MIC29710-3.3BT, MIC29710-5.0BT Datasheet (MICREL)

Download
Page 1
MIC29710/29712 Micrel
MIC29710/29712
7.5A Fast-Response LDO Regulator
General Description
The MIC29710/2 is available in two versions: the three pin fixed output MIC29710 and the five pin adjustable output voltage MIC29712. All versions are fully protected against overcurrent faults, reversed lead insertion, overtemperature operation, and positive and negative transient voltage spikes.
A TTL compatible enable (EN) control pin supports external on/off control. If on/off control is not required, the device may be continuously enabled by connecting EN to IN.
The MIC29710/2 is available in the standard three and five pin TO-220 package with an operating junction temperature range of 0°C to +125°C.
For applications requiring even lower dropout voltage or input voltage greater than 16V, see the MIC29750/29752.
Ordering Information
Features
• Fast transient response
• 7.5A current capability
• 700mV dropout voltage at full load
• Low ground current
• Accurate 2% guaranteed tolerance
• “Zero” current shutdown mode (MIC29712)
• No minimum load current
• Fixed voltage and adjustable versions
Applications
• Pentium™, Pentium Plus™, and Power PC™ processor supplies
• High-efficiency “green” computer systems
• High-efficiency linear power supplies
• High-efficiency switching supply post regulator
• Battery-powered equipment
T ypical Application
MIC29710
V
IN
IN
GND
Fixed Regulator Configuration
OUT
Part Number Temp. Range* Voltage Current Package
MIC29710-3.3BT 0°C to +125°C 3.3V 7.5A TO-220-3 MIC29710-5.0BT 0°C to +125°C 5.0V 7.5A TO-220-3 MIC29712BT 0°C to +125°C Adj. 7.5A TO-220-5
* Junction Temperature
MIC29712
V
OUT
On Off
V
IN
V
EN
IN
OUT
GND
= 1.240
OUT
ADJ
R1
R2
R1
R2
1
V
Adjustable Regulator Configuration
OUT
3-104 1997
Page 2
MIC29710/29712 Micrel
Pin Configuration
1 2 3
MIC29710BT
On all devices, the Tab is grounded.
Pin Description
3-Pin TO-220 (MIC29710)
Pin Number Pin Name Pin Function
1 IN Unregulated Input: +16V maximum supply. 2 GND Ground: Internally connected to tab (ground). 3 OUT Regulated Output
5-Pin TO-220 (MIC29712)
Pin Number Pin Name Pin Function
1 EN Enable (Input): Logic-level ON/OFF control. 2 IN Unregulated Input: +16V maximum supply. 3 GND Ground: Internally connected to tab (ground). 4 OUT Regulated Output 5 ADJ Output Voltage Adjust: 1.240V feedback from external resistive divider.
12345
MIC29712BT
3
Absolute Maximum Ratings
Input Supply Voltage, Note 1 ...................... –0.7 V to +20V
Power Dissipation ....................................Internally Limited
Storage Temperature Range ................... –65°C to +150°C
Lead Temperature (Soldering, 5 sec.) ...................... 260°C
1997 3-105
Operating Ratings
Operating Junction Temperature .................0°C to +125°C
θJC (TO-220) .............................................................2°C/W
θJA (TO-220) ...........................................................55°C/W
Page 3
MIC29710/29712 Micrel
Electrical Characteristics
All measurements at TJ = 25°C unless otherwise noted. Bold values are guaranteed across the operating temperature range. Parameter Condition Min Typ Max Units
Output Voltage 10mA ≤ IO ≤ 7.5A, (V Line Regulation IO = 10mA, (V Load Regulation VIN = V Output Voltage ∆V
Temperature Coefficient Dropout Voltage ∆V
/∆T, Note 6 20 100 ppm/°C
O
OUT
OUT
+ 1V, 10mA ≤ I
OUT
= – 1%, (Note 3)
MIC29710/29712 I
Ground Current MIC29710/29712 I
Ground Pin VIN = 0.5V less than specified V
I
GNDDO
Current at Dropout Current Limit MIC29710/29712 V
, Output Noise Voltage CL = 47µFI
e
n
(10Hz to 100kHz)
= 5.0V
VOUT
Reference (MIC29712 only)
Reference Voltage 10mA ≤ IO ≤ 7.5A, V Adjust Pin Bias Current 40 80 nA
Reference Voltage Note 7 20 ppm/°C Temperature Coefficient
Adjust Pin Bias Current 0.1 nA/°C Temperature Coefficient
+ 1V) ≤ VIN ≤ 8V, Note 2 –2 2 %
OUT
+ 1V) ≤ VIN ≤ 8V 0.06 0.5 %
≤ 7.5A, Notes 2, 6 0.2 1 %
OUT
= 100mA 80 200 mV
O
I
= 750mA 180 mV
O
= 1.5A 220 mV
I
O
= 3A 300 mV
I
O
I
= 5A 450 mV
O
IO = 7.5A 700 1000 mV
= 750mA, VIN = V
O
I
= 1.5A 20 mA
O
= 3A 36 mA
I
O
= 5A 100 mA
I
O
IO = 7.5A 250 375 mA
. I
OUT
= 0V, Note 4 11 15 A
OUT
= 100mA 260 µV
o
+ 1V ≤ VIN ≤ 8V, Note 2 1.215 1.240 1.265 V
OUT
= 10mA 1 2 mA
OUT
+ 1V 6 20 mA
OUT
MAX
120 nA
RMS
3-106 1997
Page 4
MIC29710/29712 Micrel
Parameter Conditions Min Typical Max Units
Enable Input (MIC29712 only)
Input Logic Voltage Low (Off) 0.8 V
High (On) 2.4 V
Enable (EN) Pin Input Current V
Regulator Output (Note 8) 10 µA Current in Shutdown 20 µA
General Note: Devices are ESD sensitive. Handling precautions are recommended. Note 1: The maximum continuous supply voltage is 16V. Note 2: For testing, MIC29712 V Note 3: Dropout voltage is defined as the input-to-output differential when the output voltage drops to 99% of its nominal value with V
to VIN.
Note 4: For this test, VIN is the larger of 8V or V Note 5: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground
pin current.
Note 6: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 7: V
REF
≤ V
≤ (VIN – 1 V), 2.4V ≤ VIN ≤ 8V, 10mA < IL ≤ 7.5A, TJ ≤ T
OUT
Note 8: VEN ≤ 0.8V and VIN ≤ 16V, V
OUT
= V
EN
IN
= 0.8V – 2 µA
V
EN
15 30 µA
is programmed to 5V.
+ 3V.
OUT
J MAX.
OUT
= 0.
75 µA
4 µA
+ 1V applied
OUT
3
Block Diagram
EN
IN
Thermal
Shut­down
Bias
Reference
28V
16V
O.V. I
LIMIT
Feed-
back
On/Off
OUT
ADJ
GND
1997 3-107
Page 5
MIC29710/29712 Micrel
Typical Characteristics
MIC29712 Load Transient Response
(See Test Circuit Schematic)
V
MIC29712
VIN = V
OUT
+ 1V
EN
IN
V
OUT
OUT
ADJ
GND
load (not shown):
0.1µF
93.1k 1%
49.9k 1%
Intel® Power Validator
MIC29712 Load Transient Response Test Circuit
OUT
3.525V nominal
6 × 330µF
AVX
TPSE337M006R0100
tantalum
+50mV
3.525V
–50mV
8A
6A
4A
2A
LOAD CURRENT OUTPUT VOLTAGE
200mA
0A
1ms/division
MIC29712 Line Transient Response
with 10mA Load, 10µF Output Capacitance
6.525V
4.525V
+20mV
3.525V
–20mV
OUTPUT VOLTAGE INPUT VOLTAGE
MIC29710/2 Dropout Voltage
vs. Output Current
0.6
0.5
0.4
0.3
0.2
0.1
DROPOUT VOLTAGE (V)
0
02468
OUTPUT CURRENT (A)
200µs/division
= 10mA
I
OUT
C
=10µF
OUT
DROPOUT VOLTAGE (V)
6.525V
4.525V
+20mV
3.525V
–20mV
OUTPUT VOLTAGE INPUT VOLTAGE
MIC29710/2 Dropout Voltage
1.0
0.8
0.6
0.4
0.2
vs. Temperature
I
= 7.5A
LOAD
0
-60 -30 0 30 60 90 120 150 TEMPERATURE (°C)
MIC29712 Line Transient Response
with 10mA Load, 100µF Output Capacitance
200µs/division
I
= 10mA
OUT
C
= 100µF
OUT
MIC29710-3.3
Dropout Characteristics
4
3
2
1
OUTPUT VOLTAGE (V)
0
0481216
I
= 10mA
LOAD
I
= 7.5A
LOAD
INPUT VOLTAGE (V)
3-108 1997
Page 6
MIC29710/29712 Micrel
0
50
100
150
200
250
300
350
02468
GROUND CURRENT (mA)
INPUT VOLTAGE (V)
0
50
100
150
200
250
300
350
-100 -50 0 50 100 150
GROUND CURRENT (mA)
TEMPERATURE (°C)
0
5
10
15
20
25
30
35
40
-60 -30 0 30 60 90 120 150
ENABLE CURRENT (µA)
TEMPERATURE (°C)
0.001
0.01
0.1
1
10
10x10
0
100x10
0
1x10
3
10x10
3
100x10
3
1x10
6
OUTPUT IMPEDANCE (Ω)
FREQUENCY (Hz)
MIC29710/2 Ground Current
vs. Input Voltage
10
I
= 10mA
8
6
4
2
GROUND CURRENT (mA)
0
02468
OUT
INPUT VOLTAGE (V)
MIC29710/2 Ground Current
vs. Temperature
50
40
30
I
= 3.75A
20
10
GROUND CURRENT (mA)
OUT
V
= V
+ 1
IN
OUT
0
-60 -30 0 30 60 90 120 150 TEMPERATURE (°C)
MIC29710/2 Ground Current
vs. Input Voltage
I
= 7.5A
OUT
MIC29710/2 Ground Current
vs. Temperature
I
= 7.5A
OUT
V
= V
+ 1
IN
OUT
MIC29710/2 Ground Current
vs. Temperature
12
10
8
I
6
4
2
GROUND CURRENT (mA)
0
-60 -30 0 30 60 90 120 150
= 750mA
OUT
V
= V
+ 1
IN
OUT
TEMPERATURE (°C)
MIC29710/2 Ground Current
vs. Output Current
250
200
150
100
50
GROUND CURRENT (mA)
VIN = V
0
02468
OUTPUT CURRENT (A)
OUT
+ 1
3
MIC29710-3.3 Output Voltage
3.40
3.38
3.36
3.34
3.32
3.30
3.28
3.26
3.24
OUTPUT VOLTAGE (V)
3.22
3.20
-60 -30 0 30 60 90 120 150
MIC29712 Adjust Pin Current
50
40
1997 3-109
30
20
10
ADJUST PIN CURRENT (nA)
0
-60 -30 0 30 60 90 120 150
vs. Temperature
3 DEVICES
TEMPERATURE (°C)
vs. Temperature
TEMPERATURE (°C)
MIC29710/2 Short Circuit Current vs. Temperature
12
10
8
6
4
CURRENT (A)
2
0
-60 -30 0 30 60 90 120 150
V
= 0V
OUT
TEMPERATURE (°C)
MIC29710/2 Output Impedance
vs. Frequency
MIC29712 Enable Current
vs. Temperaure
VEN = 5V
VEN = 2V
Page 7
MIC29710/29712 Micrel
Applications Information
A trade-off for the low dropout voltage is a varying base drive requirement. But Micrel’s Super ßeta PNP™ process re­duces this drive requirement to merely 2 to 5% of the load current.
MIC29710/712 regulators are fully protected from damage due to fault conditions. Current limiting is provided. The output current under overload conditions is limited to a constant value. Thermal shutdown disables the device when the die temperature exceeds the maximum safe operating temperature. Transient protection allows device (and load) survival even when the input voltage spike above and below nominal. The MIC29712 version offers a logic level ON/OFF control: when disabled, the devices draw nearly zero current.
An additional feature of this regulator family is a common pinout: a design’s current requirement may change up or down yet use the same board layout, as all of Micrel’s high­current Super ßeta PNP™ regulators have identical pinouts.
V
IN
Figure 3. The MIC29710 requires only two capacitors
for operation.
Thermal Design
Linear regulators are simple to use. The most complicated design parameters to consider are thermal characteristics. Thermal design requires the following application-specific parameters:
• Maximum ambient temperature, T
• Output Current, I
• Output Voltage, V
• Input Voltage, V
OUT
OUT
IN
V
OUT
A
First, we calculate the power dissipation of the regulator from these numbers and the device parameters from this datasheet.
PD = I
Where the ground current is approximated by 3% of I
× (1.03VIN – V
OUT
OUT
)
OUT
Then the heat sink thermal resistance is determined with this formula:
T
– T
J MAX
A
θSA = —————— – (θJC + θCS)
P
D
Where T
≤ 125°C and θCS is between 0 and 2°C/W.
J MAX
The heat sink may be significantly reduced in applications where the minimum input voltage is known and is large compared with the dropout voltage. Use a series input resistor to drop excessive voltage and distribute the heat between this resistor and the regulator. The low dropout properties of Micrel Super ßeta PNP regulators allow very significant reductions in regulator power dissipation and the associated heat sink without compromising performance. When this technique is employed, a capacitor of at least
0.1µF is needed directly between the input and regulator ground.
Please refer to Application Note 9 for further details and examples on thermal design and heat sink specification.
Capacitor Requirements
For stability and minimum output noise, a capacitor on the regulator output is necessary. The value of this capacitor is dependent upon the output current; lower currents allow smaller capacitors. MIC29710/2 regulators are stable with a minimum capacitor value of 47µF at full load.
This capacitor need not be an expensive low ESR type: aluminum electrolytics are adequate. In fact, extremely low ESR capacitors may contribute to instability. Tantalum ca­pacitors are recommended for systems where fast load transient response is important.
Where the regulator is powered from a source with a high AC impedance, a 0.1µF capacitor connected between Input and GND is recommended. This capacitor should have good characteristics to above 250kHz.
Transient Response and 5V to 3.3V Conversion
The MIC29710/2 have excellent response to variations in input voltage and load current. By virtue of their low dropout voltage, these devices do not saturate into dropout as readily as similar NPN-based designs. A 3.3V output Micrel LDO will maintain full speed and performance with an input supply as low as 4.2V, and will still provide some regulation with supplies down to 3.8V, unlike NPN devices that require 5.1V or more for good performance and become nothing more than a resistor under 4.6V of input. Micrel’s PNP regulators provide superior performance in “5V to 3.3V” conversion applications, especially when all tolerances are considered.
.
3-110 1997
Page 8
MIC29710/29712 Micrel
Adjustable Regulator Design
The adjustable regulator version, MIC29712, allows pro­gramming the output voltage anywhere between 1.25V and the 16V maximum operating rating of the family. Two resis­tors are used. Resistors can be quite large, up to 100kΩ, because of the very high input impedance and low bias current of the sense comparator. The resistor values are calculated by:
V
OUT
R1 = R2 × ( ——— – 1)
1.240
Where VO is the desired output voltage. Figure 4 shows component definition.
MIC29712BT
V
IN
4.75 to 5.25
10µF
R1
100k
R2
56.2k
33µF
V
OUT
3.45V
Enable Input
The MIC29712 versions features an enable (EN) input that allows ON/OFF control of the device. Special design allows “zero” current drain when the device is disabled—only micro­amperes of leakage current flows. The EN input has TTL/ CMOS compatible thresholds for simple interfacing with logic, or may be directly tied to VIN. Enabling the regulator requires approximately 20µA of current into the EN pin.
Voltage Standard (Ω)
R1 R2
2.85 100k 76.8k
2.9 100k 75.0k
3.0 100k 69.8k
3.1 100k 66.5k
3.15 100k 64.9k
3.3 100k 60.4k
3.45 100k 56.2k
3.525 93.1k 51.1k
3.6 100k 52.3k
3.8 100k 48.7k
4.0 100k 45.3k
4.1 100k 43.2k
Figure 5. MIC29712 Resistor Table
3
V
= 1.240V × [1 + (R1 / R2)]
OUT
Figure 4. Adjustable Regulator with Resistors
1997 3-111
Loading...
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use