NCV8851
http://onsemi.com
3
PACKAGE PIN DESCRIPTIONS − 20 Lead TSSOP
Package Pin# Pin Symbol Function
1 SYNC External clock synchronization input.
2 V
IN_CS
Supply input for the internal current sense amplifier.
3 V
IN_IC
Supply input for internal logic and analog circuitry.
4 BST Supply input for the floating top gate driver. An external diode, D
BST
, from 6V
OUT
and a
0.1 mF to 1 mF capacitor, C
BST
, to V
SW
forms a boost circuit.
5 GH Gate driver output for the external high−side NMOS FET.
6 V
SW
Switch−node. This pin connects to the source of the high−side MOSFET and drain of the
low−side MOSFET. This pin serves as the switch output to the inductor.
7 GL Gate driver output for the external low−side NMOS FET.
8 PGND Power Ground. Ground reference for the high−current path including the NMOS FETs and
output capacitor.
9 6V
OUT
Output of internal fixed 6.0 V LDO.
10 AGND Analog Ground. Ground reference for the internal logic and analog circuitry as well as R
OSC
and the compensators.
11 EN Enable input. When disabled, the LDO, internal logic and analog circuitry and gate drivers
enter sleep mode, drawing under 1 mA.
12 V
IN
Supply input for the SMPS.
13 V
FB
SMPS’s voltage feedback. Inverting input to the voltage error amplifier. Connect to V
OUT
through a resistive divider.
14 V
COMP
SMPS’s voltage error amplifier output and non−inverting input to the current error amplifier.
15 C
COMP
SMPS’s current error amplifier output and inverting input to the PWM comparator.
16 C
FB
SMPS’s current feedback. Inverting input to the current error amplifier.
17 CS
OUT
Single−ended output of the differential current sense amplifier. Connect to C
FB
through a
resistor. Non−inverting input to the cycle−by−cycle overcurrent comparator.
18 CSN Differential current sense amplifier inverting input.
19 CSP Differential current sense amplifier non−inverting input.
20 R
OSC
Oscillator’s frequency adjust pin. Resistor to ground sets the oscillator frequency.
MAXIMUM RATINGS (Voltages are with respect to AGND unless otherwise indicated.)
Rating
Value Unit
Dc Supply Voltage (V
IN
)
Peak Transient Voltage (Load Dump, EN = 0 V)
−0.3 to 20
45
V
Dc Supply Voltage (V
IN_CS
) 46 V
Dc Supply Voltage (V
IN_IC
) 6.5 V
Pin Voltage (V
SW
)
t
≤ 50 ns
−0.7 to 40.7
−2
V
Pin Voltage (BST, GH) 46 wrt PGND
7 wrt V
SW
V
Pin Voltage (GL) −0.3 to 7 wrt PGND V
Pin Voltage (EN) −0.3 to 40 V
Pin Voltage (CSP, CSN) −0.3 to 10 V
Pin Voltage (V
FB
, V
COMP
, CS
OUT
, C
FB
, C
COMP
, SYNC, R
OSC
, 6V
OUT
) −0.3 to 7 V
Pin Voltage (PGND) −0.3 to 0.3 V
Operating Junction Temperature −40 to 150 °C
Storage Temperature Range −65 to 150 °C
Peak Reflow Soldering Temperature: Lead−free 60 to 150 seconds at 217°C 265 peak °C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
