2.5V (both adjustable)and 12V supplies for use in
portableand PCMCIA applications.
The internal architecture allows to operate with
minimum external componentscount. A very high
switching frequency (200/300 KHz or externally
synchronizable) optimizes their physical dimensions.
Synchronous rectification and pulse skipping
mode for the buck sections optimise the overall
efficiencyover a wide load current range.
The two high performance PWM controllers for
1.8V and 2.5V lines are monitored for overvoltage, undervoltage and overcurrent conditions.
On detection of a fault, a POWER GOOD signal
is generated and a specific shutdown procedure
takes place to preventphysical damage and data
corruption.
A disable function allows to manage the output
power sections separately, optimising the quiescent consumptionof theIC in stand-byconditions.
2.5V
5V
to
25V
L5994
POWER
SECTION
1.8V
µP
SYNC
POWER
MANAGEMENT
& SYSTEM
SUPERVISOR
D98IN862
September 1999
This is preliminary information on a new product now in development. Details are subject to change withoutnotice.
12V LDO
5.1V LDO
3.39V REF
POWER GOOD
MEMORY
PERIPHERALS
1/8
L5994
ABSOLUTE MAXIMUM RATINGS
SymbolParameterValueUnit
V
I
OUT
IN
V
I
I
IN
T
J
Power Supply Voltage on V
IN
Maximum Pin Voltage to Pins 1, 24, 25, 32-0.5 to (VIN+5)V
Input Current Except V13IN and V
IN
Output Current Digital Output-15 to +15mA
Junction Temperature-55 to 150°C
1H1STRAPSection 1 section bootstrap capacitor connection
2V
3SREG5Signal 5V. It should be connected to PREG5 pin.
4V1SWAlternative device supply voltage.
5V1SNSThispin connects to the (-) input of the section 1 internal current sense comparator
6I1SNSThis pin connects to the (+) input of the section 1 internal current sense comparator
7COMP1Feedback input for the section 1.
8SOFT1Soft-start input of the section 1. The soft-start time is programmed by an external capacitor
9CRSTInput used for start-up and shut-down timing. A capacitor defines a time of 2ms/nF.
10PWROK1Power-good diagnostic signal. This output is driven high when section 1 is enabled and
11RUN1Control input to enable/disable the section 1. A high level (>2.4V) enables this section, a low
12VREFInternal +2.5V high accuracy voltagegenerator. It can source 5mA to external load. Bypass to
13SGNDSignal ground. Reference for internal logic circuitry. It must be routed separately from high
14NOSKIPPulse skipping mode control. A high level (>2.4V) disables pulse skipping at low load current,
15OSCOscillator frequency control: connect to 2.5V to select 300KHz operation, to ground or to 5V
16RUN2Control input to enable/disable the section 2. A high level (>2.4V) enables this section, a low
17SOFT2Soft-start input for thesection 2. The soft-start time is programmed by an external capacitor
18COMP2Feedback input for the section 2.
19I2SNSThis pin connects to the (+) input of the section 2 internal current sense comparator
20V2SNSThis pin connects to the (-) input of the section 2 internalcurrent sense comparator
21V13IN12V regulator input supply voltage, included between 13 and 20V. This voltage can be
22REG1212V regulatoroutput voltage. It can source up to 150mA toan external load
23PWROK2Power good diagnostic signal. This output is driven high when section 2 is enabledand
24H2STRAPSection 2 bootstrap capacitor connection
25H2GATEGate- driver output for the section 2high-side N-MOS
26H2SRCSection 2 high-side N-MOS source connection
27R2GATEGate- driver output for the section 2low- side N-MOS (synchronous rectifier).
28PGNDCurrent return for drivers
29PREG5+5V regulator supply. Used mainly for bootstrap capacitors. It should bebypassed to ground.
30R1GATEGate-driver output for the section 1 low-side N-MOS (synchronous rectifier).
31H1SRCSection 1 high-side N-MOS source connection
32H1GATEGate-driver output for the section 1 high-side N-MOS
IN
Device supply voltage. From 5.0 to 25V
connected between this pin and SGND. Approximately, 1ms/nF @ full load.
running properly, after a delay defined by the CRST capacitor.
level (<0.8V) shuts it down
ground with a 4.7µF capacitor to reduce noise.
current returns.
a low level (<0.8V) enables it.
for 200KHz operation. A proper external signal can synchronize the oscillator
level (>0.8V) shuts it down.
connected between this pin and GND. Approximately, 1ms/nF @full load.
supplied by a flyback winding.
running properly, after a delay defined by CRST capacitor
L5994
3/8
L5994
ELECTRICALCHARACTERISTICS
IN
= 12V; TJ=25°C;V
(V
OSC
= GND; unless otherwise specified.)
SymbolParameterTest ConditionMin.Typ.Max.Unit
DC CHARACTERISTICS
V
IN
I
2
I
2
Input Supply Voltage5.025V
Operating Quiescent CurrentR1GATE= R2GATE = OPEN
Input Voltage Range1320V
Output VoltageI22= 0 to 120mA11.5412.012.48V
Current LimitingV
Short Circuit CurrentV
Input Voltage ClampI
”One Shot” Activation ThresholdV
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumesno responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is
granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics
1999 STMicroelectronics – Printed in Italy – AllRightsReserved
STMicroelectronics GROUP OF COMPANIES
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Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A.
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8/8
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