. ."
-
SLUS377B - JULY 1999 - REVISED MAY 2000
Precision Positive Linear Voltage Regulator
0.2 V Dropout at 200 mA
Ensured Reverse Input/Output Voltage
SOIC
DP PACKAGES
(TOP VIEW)
VOUT
GND
GND
VSENSE
Isolation with Low Leakage
Adjustable Output Voltage (Down to 1.25 V)
Load Independent Low Quiescent Current
(10 A typical)
Load Regulation of 5 mV from 0 mA to
200 mA
Logic Shutdown Capability
Shutdown Quiescent Current Below 2 A
Short Circuit Protection - Duty Cycle
Limiting
Remote Load Voltage Sense for Accurate
Load Regulation
1
8
2
7
3
6
4
5
VIN
GND
GND
OFFB
TSSOP
PW PACKAGES
(TOP VIEW)
VIN
N/C
N/C
VOUT
1
8
2
7
3
6
4
5
OFFB
N/C
VSENSE
GND
description
The UCC386/7/8 positive linear pass regulator series is tailored for low-dropout applications where extremely
low quiescent power is required. Fabricated with BiCMOS technology ideally suited for low input to output
differential applications, the UCC386/7/8 will pass 200 mA while requiring only 200 mV of input voltage
headroom. Quiescent current is typically less than 10 µA. To prevent reverse current conduction, on-chip
circuitry limits the minimum forward voltage to 50 mV typical. Once the forward voltage limit is reached, the
input-output differential voltage is maintained as the input voltage drops until undervoltage lockout disables the
regulator.
block diagram and application circuit
SWITCH CONTROL
VOUT
LOAD
VIN
1
8
+
+
–
GND
GND
2
7
+
1.25 V
RS1
GND
3
R1
VSENSE
R1
R2
UCC386
1.025 m
625 k
UCC387
1.875 m
625 k
UCC388
0
OPEN
R2
OVERCURRENT,
HICCUP CONTROL
& THERMAL
SHUTDOWN
GND
6
4
OFFB
5
RS2
UCC388 ONLY
FROM OPEN DRAIN
SHUTDOWN COMMAND
UDG-98087
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright 2000, Texas Instruments Incorporated
#$&"( $# ' )&&#( ' $ %)! ( $# (
&$)(' $#$&" ($ '% ( $#' %& ( (&"' $ +' #'(&)"#('
'(#& *&&#(, &$)( $# %&$'' # $' #$( #''& !, #!)
('( # $ !! %&"(&'
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description (continued)
The UCC386 has an on-chip resistor network for preset to regulate at 3.3 V, while the UCC387 has a fixed 5-V
output. The UCC388 requires an external resistor network that can be programmed for output voltages down
to 1.25 V. The output voltage is regulated to 1.5% at room temperature and better than 2.5% over the entire
operating temperature range.
Short-circuit current is internally limited. The device responds to a sustained overcurrent condition by limiting
the duty cycle of the load to 12.5% typical. This drastically reduces the power dissipation during short circuit
such that heat sinking, if at all required, must only accommodate normal operation.
Internal power dissipation is further controlled with thermal overload protection circuitry. Thermal shutdown
occurs if the junction temperature exceeds 140°C. The chip remains in the off state until the temperature drops
to 115°C.
Pulling OFFB low commands a low-power shutdown mode, which requires less than 2-µA quiescent current.
These devices are available in the 8-pin TSSOP (PW) and 8-pin SOIC (DP) surface-mount power packages.
For other packaging options consult the factory.
AVAILABLE OPTIONS
OUTPUT VOLTAGE (V)
TA
0°C to 70°C
PACKAGE DEVICES
MIN
TYP
MAX
SOIC-8 (DP)
TSSOP-8 (PW)
3.22
3.30
3.38
UCC386DP
UCC386PW
4.785
5.000
5.125
UCC387DP
UCC387PW
UCC388DP
UCC388PW
ADJ
† All package types are available taped and reeled. Add TR suffix to device type (e.g.
UCC386DPTR) to order quantities of 3000 devices per reel.
absolute maximum ratings over operating free-air temperature (unless otherwise noted)†
VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 V
OFFB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to VIN 0.3 V
Storage Temperature, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to 150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
‡ Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and
considerations of packages. All voltages are referenced to GND.
electrical characteristics, TA = TJ = 0 C to 70 C, VIN = VOUT+1.5 V, IOUT = 0 mA, COUT = 0.1 F (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
3.25
3.3
3.35
V
3.22
3.3
3.38
13
25
5
10
mV
500
µVRMS
mV
UCC386 Fixed 3.3 V Output
Output voltage
TA = 25°C
Over temperature
Line regulation
VIN = 3.45 V to 8.5 V,
IOUT = 10 mA
Load regulation
IOUT = 1 mA to 200 mA
TJ = 25°C,
BW = 10 Hz to 10 kHz
200
VOUT = 3.20 V
200
VOUT = 3.20 V
50
Output noise voltage
Dropout voltage,
voltage VIN-VOUT
VIN VOUT
2
IOUT = 200 mA,
IOUT = 50 mA,
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V
mV
mV
SLUS377B - JULY 1999 - REVISED MAY 2000
electrical characteristics, TA = TJ = 0 C to 70 C, VIN = VOUT+1.5 V, IOUT = 0 mA, COUT = 0.1 F (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
260
550
850
mA
225
375
525
mA
12.5
14
%
900
1250
µs
10
20
µA
5
µA
0.5
V
UCC386 Fixed 3.3 V Output (continued)
Peak current limit
VOUT = 0V
Overcurrent threshold
Current limit duty cycle
VOUT = 0 V
Overcurrent timeout, TON
VOUT = 0 V
Quiescent current
OFFB = VIN
Shutdown quiescent current
VIN ≤ 8.5 V,
Shutdown threshold (OFF)
VIN = 8.5 V
0
See Note 1
VIN 0.5 V
Shutdown threshold (ON)
Reverse leakage current
550
OFFB ≤ 0.5 V
0 V < VIN < VOUT,
VOUT < 3.35 V, at VIN
0 V < VIN < VOUT,
VOUT < 3.35 V, at VOUT
2
Bias current at VSENSE pin
V
10
µA
10
µA
µA
2
UCC387 Fixed 5 V Output
Output voltage
TA = 25°C
Over full temperature range
Line regulation
VIN = 5.5 V to 8.5 V,
IOUT = 10 mA
Load regulation
IOUT = 1 mA to 200 mA
TJ = 25°C,
BW = 10 Hz to 10 kHz
200
IOUT = 200 mA,
IOUT = 50 mA,
VOUT = 4.75 V
200
Dropout voltage,
voltage VIN-VOUT
VIN VOUT
VOUT = 4.75 V
50
Peak current limit
VOUT = 0 V
Output noise voltage
4.925
5
5.075
4.785
5
5.125
13
25
5
10
mV
500
µVRMS
mV
260
Overcurrent threshold
225
Current limit duty cycle
VOUT = 0 V
Overcurrent timeout, TON
VOUT = 0 V
Quiescent current
OFFB = VIN
Shutdown quiescent current
VIN ≤ 8.5 V,
Shutdown threshold (OFF)
VIN = 8.5 V
0
See Note 1
VIN 0.5 V
Shutdown threshold (ON)
Reverse leakage current
550
OFFB ≤ 0.5 V
V
V
mV
mV
550
850
mA
375
525
mA
12.5
14
%
900
1250
µs
10
20
µA
2
5
µA
0.5
V
V
0 V < VIN < VOUT,
VOUT < 3.35 V, at VIN
10
µA
0 V < VIN < VOUT,
VOUT < 3.35 V, at VOUT
10
µA
Bias current at VSENSE pin
µA
2
UCC388 Adjustable Output
Output voltage
TA = 25°C
Over full temperature range
Line regulation
VIN = 2.5V to 8.5 V,
Load regulation
IOUT = 1 mA to 200 mA
TJ = 25°C,
Output noise voltage
Dropout voltage,
voltage VIN-VOUT
VIN VOUT
IOUT = 200 mA,
IOUT = 50 mA,
Peak current limit
VOUT = 0 V
1.23
1.25
1.27
1.22
1.25
1.28
10
40
mV
5
10
mV
500
µVRMS
mV
IOUT = 10 mA, VOUT = 1.25 V
BW = 10 Hz to 10 kHz
200
VOUT = 3.20 V
200
VOUT = 3.20 V
Overcurrent threshold
50
V
V
mV
260
550
850
mA
225
375
525
mA
NOTE 1: An internal 100-nA pullup is provided for this function.
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SLUS377B - JULY 1999 - REVISED MAY 2000
electrical characteristics, TA = TJ = 0 C to 70 C, VIN = VOUT+1.5 V, IOUT = 0 mA, COUT = 0.1 F (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
UCC388 Adjustable Output (continued)
Current limit duty cycle
VOUT = 0 V
Overcurrent timeout, TON
VOUT = 0 V
Quiescent current
OFFB = VIN
Shutdown quiescent current
VIN ≤ 8.5 V,
Shutdown threshold (OFF)
VIN = 8.5 V
0
Shutdown threshold (ON)
See Note 1
VIN 0.5 V
Reverse leakage current
550
OFFB ≤ 0.5 V
0 V < VIN < VOUT,
VOUT < 3.35 V, at VIN
0 V < VIN < VOUT,
VOUT < 3.35 V, at VOUT
Bias current at VSENSE pin
12.5
14
%
900
1250
µs
10
20
µA
5
µA
0.5
V
2
V
10
µA
10
µA
50
Minimum operating voltage
nA
2.5
V
NOTE 1: An internal 100-nA pullup is provided for this function.
pin descriptions
GND: Chip Ground. All voltages are measured with respect to this pin. This is the low-noise ground reference
for input regulation. The output decoupling capacitor should be tied between VOUT and GND.
OFFB: Shutdown, active low. This pin must be externally pulled to GND to turn off the IC. Pulling this pin high
turns on the IC. This pin is internally pulled to VIN by 100-nA current source.
VIN: Positive supply input for the regulator. Bypass this pin to GND with at least 0.1 µF of low ESR, ESL
capacitance if the source is located further than 1 inch from the device.
VOUT: Output of the regulator. The regulator does not require a minimum output capacitance for stability,
however a small capacitor is recommended to improve transient response. Choose the appropriate size
capacitor for the application with respect to the required transient loading. For example, if the load is very
dynamic, a large capacitor will smooth out the response to load steps.
VSENSE: Externally programmable voltage sense node. For the UCC388, connect resistor divider network
between VOUT, VSENSE and GND to provide custom regulation level. For the UCC386 and UCC387, connect
this pin to VOUT as close to the load as possible.
APPLICATION INFORMATION
load independent current consumption
This series of LDOs is based on CMOS circuitry and uses a high-side P-channel pass element. Consequently,
the current consumed by the LDO is extremely low at 10 µA under normal operating conditions and does not
vary with load. The shutdown mode (OFFB = GND) consumes only 2 µA, making this series an excellent choice
for battery applications.
reverse voltage standoff
These LDOs are designed to operate with the voltage at the output greater than the voltage at the input. This
can be an advantage where a circuit needs to be powered from two separate power sources that must be kept
isolated, such as selecting between one of two or more batteries.
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APPLICATION INFORMATION
overcurrent protection
The UCC386/7/8 uses a fixed, absolute, current limit in conjunction with a timed overcurrent function that
significantly reduces power dissipation in the event of a shorted load (see Figure 1). In this diagram, a 100-mA
load is applied to the output of the LDO. At some point, a fault is applied. When the current level exceeds the
overcurrent threshold of about 300 mA, a timer is started. If the current does not fall below the overcurrent
threshold before the timer times out, about 5.6 ms, the LDO declares an overcurrent condition exists and turns
off its output for about 5.6 ms. Note that the output current is internally limited to 600 mA. After the output has
been off for 5.6 ms, it is turned on for about 800 µs and again limited to 600 mA. If the current does not fall below
the overcurrent threshold before the 800-µs timer expires, the output is again turned off for 5.6 ms. This process
repeats itself until the fault condition is removed from the output of the LDO. The average current supplied to
the faulted load by the LDO is approximately 112 mA. This is well below the maximum rated current of 200 mA
of the LDO. Therefore, for most applications that have adequate thermal dissipation for the LDO to operate at
full rated load, the thermal dissipation will also be adequate in a faulted condition.
800 µ s
5.6 ms
5.6 ms
600 mA
300 mA
100 mA
0
FAULT
APPLIED
FAULT
REMOVED
UDG-98088
Figure 1. Current Waveform During a Fault
thermal shutdown
The LDOs have a thermal shutdown circuit that will turn the LDO output off before the die temperature reaches
damaging levels. When the die cools, the LDO will again function. The thermal shutdown circuit has a turn-off
threshold of nominally 140°C, and a turn-on threshold of 115°C. These temperatures insure that the LDO will
not be damaged due to excessive power dissipation.
maximum load recovery
The LDO will start a load that has a large capacitance and a dc current component. One of the consequences
of the LDOs fault behavior is a maximum output capacitor value and load current that the LDO can restart after
an overcurrent condition has been declared. Figure 2 shows the maximum load that the LDO can re-start from
a faulted condition with a given output filter capacitor. Note that the LDO can start a much higher load than it
can restart after a fault. If the LDO is hiccuping into a load that it cannot re-start, either momentarily
disconnecting the load or a power cycle allows the LDO to start the load.
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SLUS377B - JULY 1999 - REVISED MAY 2000
APPLICATION INFORMATION
maximum load recovery (continued)
CRITICAL LOAD CURRENT
vs
OUTPUT CAPACITANCE
200
CL - Load Current - mA
160
120
UCC386
80
40
UCC387
0
20
60
100
140
180
CO - Output Capacitance - F
Figure 2.
using OFFB
The OFFB pin is used to turn the output of the LDO on or off from some external source. There are two things
to note when using this pin. The first is that after taking OFFB high (on), the LDO will require up to about 2 ms
to start and stabilize. The second item is that OFFB is designed to be driven from an open-drain-type output.
Internally, this pin is pulled high by a weak 100-nA current source, and will normally be at the input supply
voltage, so the driving circuitry must be able to withstand the voltage applied to the input of the regulator. Also,
depending upon load, if the OFFB pin is driven (overriding the internal pull-up) high with a fast edge signal, there
may be a brief pulse on the output, followed by no output, with the regulator coming on and stabilizing about
2 ms after the OFFB pin was driven high. This output pulse is never more than the normal output voltage of the
regulator and is about 200 µs in length.
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APPLICATION INFORMATION
output capacitance and transient response
The transient response of the regulator is heavily influenced by the capacitor on the output. In general, larger
capacitors produce less voltage variation during load changes, but take longer to stabilize (quit wiggling). Note
that no output capacitor is required for a stable output. However, if the load exhibits sharp changes in current
requirements, and temporary deviations from the nominal output voltage must be minimized, some output filter
capacitor will be needed.
UCC388 output voltage programming
Referring to the applications diagram on the front page of the data sheet, the output voltage is given by:
V
O
1.25
R
R
S1
S2
R
S2
Note that for the UCC388, the internal resistor R2 is open.
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7
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accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
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TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
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Copyright 2000, Texas Instruments Incorporated