SI9136DB Vishay, SI9136DB Datasheet - Page 14

• Manufacturer Part Number: SI9136DB
• Description: Pulse Width Modulation (PWM) Controller IC
• Manufacturer: Vishay

Specifications of SI9136DB

• Silicon Manufacturer: Vishay
• Application Sub Type: Power Supply Controller
• Kit Application Type: Power Management
• Silicon Core Number: SI9136
• Kit Contents: Board
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Si9136
Vishay Siliconix
Grounding:
There are two separate grounds on the Si9136, analog signal
ground (GND) and power ground (PGND). The purpose of two
separate grounds is to prevent the high currents on the power
devices (both external and internal) from interfering with the
analog signals. The internal components of Si9136 have their
grounds tied (internally) together. These two grounds are then
tied together (externally) at a single point, to ensure Si9136
noise immunity.
This separation of grounds should be maintained in the
external circuitry, with the power ground of all power devices
being returned directly to the input capacitors, and the small
signal ground being returned to the GND pin of Si9136.
ON/OFF Function
Logic-low shuts off the appropriate section by disabling the
gate drive stage. High-side and low-side gate drivers are
turned off when ON/OFF pins are logic-low.
enables the DH and DL pins.
Stability:
Buck Converters:
In order to simplify designs, the Si9136 requires no specified
external components except load capacitors for stability
control. Meanwhile, it achieves excellent regulation and
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14
Logic-high
efficiency. The converters are current mode control, with a
bandwidth substantially higher than the LC tank dominant pole
frequency of the output filter. To ensure stability, the minimum
capacitance and maximum ESR values are:
Where V
Rcs is the current sensing resistor in ohms and BW = 50 khz
With the components specified in the application circuit
(L = 10 H, RCS = 0.02
approximately 0.1
at approximately 50 kHz, with minimum phase margin of 65 ,
and dc gain above 50 dB.
Other Outputs
The Si9136 also provides a 3.3-V reference which can be
external loaded up to 1 mA, as well as, a 5-V LDO output which
can be loaded 30 mA, or even more depending on the system
application. When the 5-V buck converter is turned on, the 5-V
LDO output is shorted with the 5-V buck converter output, so its
loading capability is substantially increased. For stability, the
3.3-V reference output requires a 1- F capacitor, and 5-V LDO
output requires a 4.7- F capacitor.
C
LOAD
REF
2
= 3.3 V, V
V
REF
, the converter should have a bandwidth
x
OUT
R
CS
is the output voltage (5 V or 3.3 V),
x
,
BW
C
OUT
S-00583—Rev. C, 03-Apr-00
ESR
Document Number: 70818
= 330 F,
V
OUT
V
REF
x R
cs
ESR