SI9160BQ-T1 Vishay, SI9160BQ-T1 Datasheet - Page 9

• Manufacturer Part Number: SI9160BQ-T1
• Description: IC, VOLTAGE MODE PWM CTRL, 6V, TSSOP-16
• Manufacturer: Vishay

Specifications of SI9160BQ-T1

• Input Voltage: 6V
• Output Voltage: 5.2V
• Output Current: 10mA
• Frequency: 2MHz
• Power Dissipation Pd: 925mW
• Supply Voltage Range: 2.7V To 6V
• Digital Ic Case Style: TSSOP
• No. Of Pins: 16
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-16
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Another benefit of powering from the output voltage is it
provides minimum load on the converter. This prevents the
converter from skipping frequency pulses typically referred to
as Burst or Pulse-Skipping modes. Pulse skipping mode could
be dangerous, especially if it generates noise in RF, IF, or
signal processing frequency bands.
Enable and Under Voltage Shutdown
The Si9160 is designed with programmable under-voltage
lockout and enable features. These features give designers
flexibility
under-voltage lockout threshold is 1.2 V. With a simple resistor
divider from V
V
allows remote shutdown as needed.
Gate Drive and MOSFETs
The gate drive section is designed to drive the high-side
p-channel switch and low-side n-channel switch. The internal
40 ns break-before-make (BBM) timing prevents both
MOSFETs from turning-on simultaneously. The BBM circuit
monitors both drive voltages, once the gate-to-source voltage
drops below 2.5 V, the other gate drive is delayed 40-ns before
it is allowed to drive the external MOSFET (see Figure 2 for
timing diagram). This smart gate drive control provides
additional assurance that shoot-through current will not occur.
The MOSFET used is the Si6801, an n- and p-channel in a
single package TSSOP-8. The Si6801 is optimized to have
very low gate charge and gate resistance. This results in a
great reduction in gate switching power losses. The average
time to switch on and off a MOSFET in a conventional structure
is about 20 ns. The Si6801 will switch on and off in < 5 ns, see
Figure 3.
Document Number: 70029
S-40700—Rev. H, 19-Apr-04
DD
CH1
CH3
CH2
CH4
voltage. The ENABLE pin, a TTL logic compatible input,
FIGURE 2. Gate Drive Timing Diagrams
to
DD
customize
, Si9160 can be programmed to turn-on at any
CH1: C
CH3: COMP; CH4: D
OSC
; CH2: D
the
S
R
converter
design.
The
Stability Components
A voltage mode boost converter is normally stabilized with
simple lag compensation due to the additional 90_ phase lag
introduced by the additional right hand plane zero, as well as
having a duty factor dependent resonant frequency for the
output filter. The stability components shown in Figure 1 have
been chosen to ensure stability under all battery conditions
while maintaining maximum transient response. To do this we
have used a 2-pole-zero pair configuration (type 3 amplifier
configuration). Figure 4 shows the bode plot for the above
circuit, maintaining > 50_ phase margin over the entire battery
voltage range.
FIGURE 4. Stability, with 1-cell Li battery input, 5 V @ 600-mA
+50
−50
Note the Speed
These MOSFETs have switching speeds of <5 ns. This high speed is
due to the fast, high current output drive of the Si9160 and the opti-
mized gate charge of the Si6801.
N-Channel
Turn-On
0
10
5 ns/DIV, 2 V/DIV
0
10
Li Battery Voltage
Low Charge 2.7 V
1
output.
FIGURE 3. Gate Switching Times
10
Frequency (Hz)
2
Gain
Phase
10
3
10
4
Phase Margin
> 50_
Vishay Siliconix
10
5
5 ns/DIV, 2 V/DIV
10
6
+180_
0_
−180_
Li Battery Volt-
age Full
Charge 4.0 V
N-Channel
Turn-Off
www.vishay.com
Si9160
9